Armen Zakarian

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Name: Zakarian, Armen

Organization: University of California , USA

Department: Department of Chemistry and Biochemistry

Title: Professor(PhD)

TOPICS

Organic Chemistry

Fluorination

Chemicals
References

Cutting-Edge and Time-Honored Strategies for Stereoselective Construction of C–N Bonds in Total Synthesis

Co-reporter:Artur K. Mailyan, John A. Eickhoff, Anastasiia S. Minakova, Zhenhua Gu, Ping Lu, and Armen Zakarian

Chemical Reviews 2016 Volume 116(Issue 7) pp:4441

Publication Date(Web):March 25, 2016

DOI:10.1021/acs.chemrev.5b00712

The main objective of this review is to provide a comprehensive survey of methods used for stereoselective construction of carbon–nitrogen bonds during the total synthesis of nitrogen-containing natural products that have appeared in the literature since 2000. The material is organized by specific reaction in order of decreasing number of applications in natural product synthesis. About 800 total syntheses of natural products with stereogenic carbon–nitrogen bonds described since 2000 have been reviewed.

Lithium Enolates in the Enantioselective Construction of Tetrasubstituted Carbon Centers with Chiral Lithium Amides as Noncovalent Stereodirecting Auxiliaries

Co-reporter:Kai Yu, Ping Lu, Jeffrey J. Jackson, Thuy-Ai D. Nguyen, Joseph Alvarado, Craig E. Stivala, Yun Ma, Kyle A. Mack, Trevor W. HaytonDavid B. Collum, Armen Zakarian

Journal of the American Chemical Society 2016 Volume 139(Issue 1) pp:527-533

Publication Date(Web):December 7, 2016

DOI:10.1021/jacs.6b11673

Lithium enolates derived from carboxylic acids are ubiquitous intermediates in organic synthesis. Asymmetric transformations with these intermediates, a central goal of organic synthesis, are typically carried out with covalently attached chiral auxiliaries. An alternative approach is to utilize chiral reagents that form discrete, well-defined aggregates with lithium enolates, providing a chiral environment conducive of asymmetric bond formation. These reagents effectively act as noncovalent, or traceless, chiral auxiliaries. Lithium amides are an obvious choice for such reagents as they are known to form mixed aggregates with lithium enolates. We demonstrate here that mixed aggregates can effect highly enantioselective transformations of lithium enolates in several classes of reactions, most notably in transformations forming tetrasubstituted and quaternary carbon centers. Easy recovery of the chiral reagent by aqueous extraction is another practical advantage of this one-step protocol. Crystallographic, spectroscopic, and computational studies of the central reactive aggregate, which provide insight into the origins of selectivity, are also reported.

Stereoselective Synthesis of Cyclic Guanidines by Directed Diamination of Unactivated Alkenes

Co-reporter:Artur K. Mailyan, Kyle Young, Joanna L. Chen, Bradley T. Reid, and Armen Zakarian

Organic Letters 2016 Volume 18(Issue 21) pp:5532-5535

Publication Date(Web):October 25, 2016

DOI:10.1021/acs.orglett.6b02778

A method for a directed stereoselective guanidinylation of alkenes is described. The guanidine unit can be delivered as an intact fragment by a hydroxy or carboxy group, usually with a high level of stereocontrol. After the guanidine delivery, the directing group can be cleaved under exceptionally mild conditions, typically by alcoholysis in the presence of acetic acid. Broad functional group tolerance and mild reaction conditions for the cycloguanidilation suggest applications in medicinal chemistry and natural products synthesis.

Total Synthesis and Structural Revision of (+)-Muironolide A

Co-reporter:Qing Xiao; Kyle Young

Journal of the American Chemical Society 2015 Volume 137(Issue 18) pp:5907-5910

Publication Date(Web):April 30, 2015

DOI:10.1021/jacs.5b03531

Muironolide A is a fascinating tetrachlorinated marine polyketide isolated from the sponge of Phorbas sp. Only 90 μg had been isolated, and the structure was established by nanoscale NMR techniques. Herein we report the total synthesis of the substance with the assigned structure of muironolide A, propose a revised structure based on NMR data, and complete the enantioselective total synthesis of muironolide A.

Direct Enantioselective Conjugate Addition of Carboxylic Acids with Chiral Lithium Amides as Traceless Auxiliaries

Co-reporter:Ping Lu; Jeffrey J. Jackson; John A. Eickhoff

Journal of the American Chemical Society 2015 Volume 137(Issue 2) pp:656-659

Publication Date(Web):January 5, 2015

DOI:10.1021/ja512213c

Michael addition is a premier synthetic method for carbon–carbon and carbon–heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B.

Synthesis and biology of cyclic imine toxins, an emerging class of potent, globally distributed marine toxins

Co-reporter:Craig E. Stivala, Evelyne Benoit, Rómulo Aráoz, Denis Servent, Alexei Novikov, Jordi Molgó and Armen Zakarian

Natural Product Reports 2015 vol. 32(Issue 3) pp:411-435

Publication Date(Web):22 Oct 2014

DOI:10.1039/C4NP00089G

Covering: up to August 2014 From a small group of exotic compounds isolated only two decades ago, Cyclic Imine (CI) toxins have become a major class of marine toxins with global distribution. Their distinct chemical structure, biological mechanism of action, and intricate chemistry ensures that CI toxins will continue to be the subject of fascinating fundamental studies in the broad fields of chemistry, chemical biology, and toxicology. The worldwide occurrence of potent CI toxins in marine environments, their accumulation in shellfish, and chemical stability are important considerations in assessing risk factors for human health. This review article aims to provide an account of chemistry, biology, and toxicology of CI toxins from their discovery to the present day.

Toward the Synthesis of Muironolide A: Synthesis and Structure of Heteroleptic LanthanideTerpyridine Complexes with 2-Oxo Amides

Co-reporter:Kyle Young;Qing Xiao

European Journal of Organic Chemistry 2015 Volume 2015( Issue 11) pp:2337-2341

Publication Date(Web):

DOI:10.1002/ejoc.201500174

Abstract

A lanthanide-catalyzed intramolecular Diels–Alder (IMDA) reaction en route to the synthesis of muironolide A is described, along with detailed crystallographic structural studies of lanthanide complexes between β-oxo amides and terpyridine. The X-ray crystallographic studies are first examples of nonsymmetric heteroleptic complexes of lanthanides with β-oxo carbonyl compounds, which reveal several structural properties that could be exploited in the development of catalytic reactions with lanthanides.

Synthesis of 2-Aminoazoles from Thioesters via α-Heterosubstituted Ketones by Copper-Mediated Cross-Coupling

Co-reporter:Hiroyuki Kobayashi, John A. Eickhoff, and Armen Zakarian

The Journal of Organic Chemistry 2015 Volume 80(Issue 20) pp:9989-9999

Publication Date(Web):September 17, 2015

DOI:10.1021/acs.joc.5b01558

Facile synthesis of a variety of α-heterosubstituted ketones under mild conditions was achieved by copper-mediated cross-coupling of thioesters with functionalized organostannanes. Application of this coupling methodology provided a concise pathway for the conversion of carboxylic acids to 2-aminoimidazoles, 2-aminothiazoles, and 2-aminooxazoles via thioesters in practical yields.

Toward the Synthesis of Nuphar Sesquiterpene Thioalkaloids: Stereodivergent Rhodium-Catalyzed Synthesis of the Thiolane Subunit

Co-reporter:Ping Lu, Aaron T. Herrmann, and Armen Zakarian

The Journal of Organic Chemistry 2015 Volume 80(Issue 15) pp:7581-7589

Publication Date(Web):July 6, 2015

DOI:10.1021/acs.joc.5b01177

A stereodivergent approach to the central thiolane subunit of Nuphar sesquiterpene thioalkaloids has been developed. This approach features a rhodium-catalyzed Stevens-type rearrangement in conjunction with an enzyme resolution reaction. Further elaboration into a polycyclic ring system via alcohol oxidation and ring-closing metathesis is also described.

10-Step Asymmetric Total Synthesis and Stereochemical Elucidation of (+)-DragmacidinD

Co-reporter:Jeffrey J. Jackson;Dr. Hiroyuki Kobayashi;Sophia D. Steffens;Dr. Armen Zakarian

Angewandte Chemie 2015 Volume 127( Issue 34) pp:10109-10113

Publication Date(Web):

DOI:10.1002/ange.201504113

Abstract

The asymmetric synthesis of dragmacidin D (1) was completed in 10 steps. Its sole stereocenter was set by using direct asymmetric alkylation enabled by a C₂-symmetric tetramine and lithium N-(trimethylsilyl)-tert-butylamide as the enolization reagent. A central Larock indole synthesis was employed in a convergent assembly of the heterocyclic subunits. The stereochemical evidence from this work strongly supports the predicted S configuration at the 6′′′ position, which is consistent with other members of the dragmacidin family of natural products.

10-Step Asymmetric Total Synthesis and Stereochemical Elucidation of (+)-DragmacidinD

Co-reporter:Jeffrey J. Jackson;Dr. Hiroyuki Kobayashi;Sophia D. Steffens;Dr. Armen Zakarian

Angewandte Chemie International Edition 2015 Volume 54( Issue 34) pp:9971-9975

Publication Date(Web):

DOI:10.1002/anie.201504113

Abstract

Enantioselective Synthesis of (−)-Maoecrystal V by Enantiodetermining C–H Functionalization

Co-reporter:Ping Lu ; Artur Mailyan ; Zhenhua Gu ; David M. Guptill ; Hengbin Wang ; Huw M. L. Davies

Journal of the American Chemical Society 2014 Volume 136(Issue 51) pp:17738-17749

Publication Date(Web):November 19, 2014

DOI:10.1021/ja510573v

The evolution of a program directed at the enantioselective total synthesis of maoecrystal V, a highly modified ent-kauranoid, is described. An early stage chiral auxiliary-directed asymmetric C–H functionalization for the construction of a key benzofuran intermediate enabled the first asymmetric synthesis of the natural enantiomer of maoecrystal V, confirming the assigned stereochemistry. A divergent course of the central intramolecular Diels–Alder reaction, which is dependent on the nature of the dienophile, initially led to the development of an unanticipated and previously unknown isomer of maoecrystal V, which we named maoecrystal ZG. In light of the reported selective and potent cytotoxic activity of maoecrystal V, the cytotoxic properties of maoecrystal ZG were also investigated.

Asymmetric Radical Addition of TEMPO to Titanium Enolates

Co-reporter:Phillip J. Mabe and Armen Zakarian

Organic Letters 2014 Volume 16(Issue 2) pp:516-519

Publication Date(Web):December 31, 2013

DOI:10.1021/ol403398u

A mild method for α-hydroxylation of N-acyl oxazolidinones by asymmetric radical addition of the 2,2,6,6-tetramethylpiperidine N-oxy (TEMPO) radical to titanium enolates was developed. The high diastereoselectivity and broad scope of the reaction show synthetic utility for the α-hydroxylation of substrates that are not tolerant to strongly basic conditions.

Stereoselective α-Fluorination of N-Acyloxazolidinones at Room Temperature within 1 h

Co-reporter:Joseph Alvarado, Aaron T. Herrmann, and Armen Zakarian

The Journal of Organic Chemistry 2014 Volume 79(Issue 13) pp:6206-6220

Publication Date(Web):June 13, 2014

DOI:10.1021/jo500957d

A direct α-fluorination of N-acyloxazolidinones based on the unique reactivity of group IVa metal enolates has been developed. The reaction is an experimentally simple, low-cost, quick, and energy-efficient alternative for asymmetric α-fluorination of N-acyloxazolidinones. Preliminary studies have shown compatibility with alkyl, alkenyl, and alkynyl, aromatic, and several heteroaromatic substituents. High diastereoselectivities have been achieved with most substrates tested, and the reaction is typically complete within 1 h at ambient temperature.

Enediolate–Dilithium Amide Mixed Aggregates in the Enantioselective Alkylation of Arylacetic Acids: Structural Studies and a Stereochemical Model

Co-reporter:Yun Ma ; Craig E. Stivala ; Ashley M. Wright ; Trevor Hayton ; Jun Liang ; Ivan Keresztes ; Emil Lobkovsky ; David B. Collum

Journal of the American Chemical Society 2013 Volume 135(Issue 45) pp:16853-16864

Publication Date(Web):May 8, 2013

DOI:10.1021/ja403076u

A combination of X-ray crystallography, 6Li, 15N, and 13C NMR spectroscopies, and density functional theory computations affords insight into the structures and reactivities of intervening aggregates underlying highly selective asymmetric alkylations of carboxylic acid dianions (enediolates) mediated by the dilithium salt of a C2-symmetric chiral tetraamine. Crystallography shows a trilithiated n-butyllithium–dilithiated amide that has dimerized to a hexalithiated form. Spectroscopic studies implicate the non-dimerized trilithiated mixed aggregate. Reaction of the dilithiated amide with the dilithium enediolate derived from phenylacetic acid affords a tetralithio aggregate comprised of the two dianions in solution and the dimerized octalithio form in the solid state. Computational studies shed light on the details of the solution structures and afford a highly predictive stereochemical model.

Total Synthesis of Maoecrystal V: Early-Stage C–H Functionalization and Lactone Assembly by Radical Cyclization

Co-reporter:Ping Lu ; Zhenhua Gu

Journal of the American Chemical Society 2013 Volume 135(Issue 39) pp:14552-14555

Publication Date(Web):September 19, 2013

DOI:10.1021/ja408231t

A total synthesis of the unusual ent-kaurane maoecrystal V is described. The synthesis strategy features a counterintuitive early disconnection of the lactone subunit to a polycyclic enol ether intermediate in order to preserve the central tetrahydrofuran ring until the beginning stages of the synthesis. This strategy enables an application of C–H functionalization at the early phase of the synthesis during the construction of a dihydrobenzofuran intermediate.

An Efficient Synthesis of the Fully Elaborated Isoindolinone Unit of Muironolide A

Co-reporter:Qing Xiao, Kyle Young, and Armen Zakarian

Organic Letters 2013 Volume 15(Issue 13) pp:3314-3317

Publication Date(Web):June 13, 2013

DOI:10.1021/ol401354a

An efficient stereocontrolled construction of the fully substituted isoindolone subunit of muironolide A is described. The approach is centered on the intramolecular Diels–Alder reaction between the enol form of the β-keto amide and an α,β,γ,δ-unsaturated ester, followed by the installation of the cyclohexene double bond.

A Simple Method for Asymmetric Trifluoromethylation of N-Acyl Oxazolidinones via Ru-Catalyzed Radical Addition to Zirconium Enolates

Co-reporter:Aaron T. Herrmann ; Lindsay L. Smith

Journal of the American Chemical Society 2012 Volume 134(Issue 16) pp:6976-6979

Publication Date(Web):April 9, 2012

DOI:10.1021/ja302552e

A Ru-catalyzed direct thermal trifluoromethylation and perfluoroalkylation of N-acyloxazolidinones has been developed. The reaction is experimentally simple and requires inexpensive reagents while providing good yields of products with good levels of stereocontrol. Preliminary studies have shown notable compatibility with functional groups, aromatics, and certain heteroaromatic substituents. The described method provides a useful alternative for the synthesis of fluorinated materials in an experimentally convenient manner.

Studies toward the Synthesis of Spirolide C: Exploration into the Formation of the 23-Membered All-Carbon Macrocyclic Framework

Co-reporter:Craig E. Stivala, Zhenhua Gu, Lindsay L. Smith, and Armen Zakarian

Organic Letters 2012 Volume 14(Issue 3) pp:804-807

Publication Date(Web):January 19, 2012

DOI:10.1021/ol203342e

The synthesis of two complex subunits en route to spirolide C is described. A key alkyllithium addition to an aldehyde joins the fragments, which are advanced in order to investigate a ring-closing metathesis to form the 23-membered all-carbon macrocyclic framework.

Stability of Cyclic Imine Toxins: Interconversion of Pinnatoxin Amino Ketone and Pinnatoxin A in Aqueous Media

Co-reporter:Jeffrey J. Jackson, Craig E. Stivala, Bogdan I. Iorga, Jordi Molgó, and Armen Zakarian

The Journal of Organic Chemistry 2012 Volume 77(Issue 22) pp:10435-10440

Publication Date(Web):November 1, 2012

DOI:10.1021/jo301632d

Pinnatoxins belong to the cyclic imine (CI) group of marine toxins with a unique toxicological profile. The need for structural integrity of the aliphatic 7-membered cyclic imine for the potent bioactivity of pinnatoxins has been experimentally demonstrated. In this study, we probe interconversion of the natural cyclic imine and its open form, pinnatoxin A amino ketone (PnTX AK), under physiologically relevant aqueous conditions. Our studies demonstrate the high stability of PnTX A. The unusual stability of the imine ring in PnTX A has implications for its oral toxicity and detoxification. These studies, as well the access to PnTX amino ketone, were enabled by the total synthesis of (+)-pinnatoxin A completed previously in our laboratory.

Approaches to dihydrooxazine ring systems and application in the synthesis of bioactive natural products

Co-reporter:Z. Gu;T. Saito;A. Zakarian

Chemistry of Heterocyclic Compounds 2012 Volume 48( Issue 1) pp:11-16

Publication Date(Web):2012 April

DOI:10.1007/s10593-012-0961-y

This review describes selected approaches to the synthesis of 4H-5,6-dihydro-1,2-oxazines and application of these methods to the synthesis of natural products containing this heterocyclic ring system. The focus is on applications and on interesting aspects of chemistry related to this subclass of natural products, as well as newer methods for the synthesis of oxazines.

Total Synthesis of Pinnatoxins A and G and Revision of the Mode of Action of Pinnatoxin A

Co-reporter:Romulo Araoz ; Denis Servent ; Jordi Molgó ; Bogdan I. Iorga ; Carole Fruchart-Gaillard ; Evelyne Benoit ; Zhenhua Gu ; Craig Stivala

Journal of the American Chemical Society 2011 Volume 133(Issue 27) pp:10499-10511

Publication Date(Web):June 6, 2011

DOI:10.1021/ja201254c

Pinnatoxins belong to an emerging class of potent marine toxins of the cyclic imine group. Detailed studies of their biological effects have been impeded by unavailability of the complex natural product from natural sources. This work describes the development of a robust, scalable synthetic sequence relying on a convergent strategy that delivered a sufficient amount of the toxin for detailed biological studies and its commercialization for use by other research groups and regulatory agencies. A central transformation in the synthesis is the highly diastereoselective Ireland–Claisen rearrangement of a complex α,α-disubstituted allylic ester based on a unique mode for stereoselective enolization through a chirality match between the substrate and the lithium amide base. With synthetic pinnatoxin A, a detailed study has been performed that provides conclusive evidence for its mode of action as a potent inhibitor of nicotinic acetylcholine receptors selective for the human neuronal α7 subtype. The comprehensive electrophysiological, biochemical, and computational studies support the view that the spiroimine subunit of pinnatoxins is critical for blocking nicotinic acetylcholine receptor subtypes, as evidenced by analyzing the effect of a synthetic analogue of pinnatoxin A containing an open form of the imine ring. Our studies have paved the way for the production of certified standards to be used for mass-spectrometric determination of these toxins in marine matrices and for the development of tests to detect these toxins in contaminated shellfish.

Highly Enantioselective Direct Alkylation of Arylacetic Acids with Chiral Lithium Amides as Traceless Auxiliaries

Co-reporter:Craig E. Stivala

Journal of the American Chemical Society 2011 Volume 133(Issue 31) pp:11936-11939

Publication Date(Web):July 11, 2011

DOI:10.1021/ja205107x

A direct, highly enantioselective alkylation of arylacetic acids via enediolates using a readily available chiral lithium amide as a stereodirecting reagent has been developed. This approach circumvents the traditional attachment and removal of chiral auxiliaries used currently for this type of transformation. The protocol is operationally simple, and the chiral reagent is readily recoverable.

Studies toward the Synthesis of Maoecrystal V

Co-reporter:Zhenhua Gu and Armen Zakarian

Organic Letters 2011 Volume 13(Issue 5) pp:1080-1082

Publication Date(Web):January 27, 2011

DOI:10.1021/ol1031238

An approach toward the synthesis of maoecrystal V is described. The synthetic strategy for this approach was designed to address unique challenges posed by the strained tetrahydrofuran ring at the center of the target structure.

A Concise Asymmetric Total Synthesis of (+)-Brevisamide

Co-reporter:Aaron T. Herrmann, Steven R. Martinez, and Armen Zakarian

Organic Letters 2011 Volume 13(Issue 14) pp:3636-3639

Publication Date(Web):June 16, 2011

DOI:10.1021/ol201283n

A new protecting-group-free synthesis of the marine monocyclic ether (+)-brevisamide is reported. The enantioselective synthesis utilizes a key asymmetric Henry reaction and an Achmatowicz rearrangement for the formation of the tetrahydropyran ring. A penultimate Stille cross-coupling allows for an efficient installation of the conjugated (E,E)-diene side chain ultimately delivering (+)-brevisamide.

Efficient Total Synthesis of Dysidenin, Dysidin, and Barbamide

Co-reporter:Elizabeth A. Ilardi ;Dr. Armen Zakarian

Chemistry – An Asian Journal 2011 Volume 6( Issue 9) pp:2260-2263

Publication Date(Web):

DOI:10.1002/asia.201100338

Dual TiRu Catalysis in the Direct Radical Haloalkylation of N-Acyl Oxazolidinones

Co-reporter:Dr. Zhenhua Gu;Aaron T. Herrmann ;Dr. Armen Zakarian

Angewandte Chemie 2011 Volume 123( Issue 31) pp:7274-7277

Publication Date(Web):

DOI:10.1002/ange.201101364

Dual TiRu Catalysis in the Direct Radical Haloalkylation of N-Acyl Oxazolidinones

Co-reporter:Dr. Zhenhua Gu;Aaron T. Herrmann ;Dr. Armen Zakarian

Angewandte Chemie International Edition 2011 Volume 50( Issue 31) pp:7136-7139

Publication Date(Web):

DOI:10.1002/anie.201101364

Valence Tautomerism in Titanium Enolates: Catalytic Radical Haloalkylation and Application in the Total Synthesis of Neodysidenin

Co-reporter:Stéphane Beaumont ; Elizabeth A. Ilardi ; Lucas R. Monroe

Journal of the American Chemical Society 2010 Volume 132(Issue 5) pp:1482-1483

Publication Date(Web):January 15, 2010

DOI:10.1021/ja910154f

A direct ruthenium-catalyzed radical chloroalkylation of N-acyl oxazolidinones capitalizing on valence tautomerism of titanium enolates has been developed. The chloroalkylation method served as the centerpiece in the enantioselective total synthesis of trichloroleucine-derived marine natural product neodysidenin.

Regio- and Stereocontrol in Rhenium-Catalyzed Transposition of Allylic Alcohols

Co-reporter:Aaron T. Herrmann ; Tatsuo Saito ; Craig E. Stivala ; Janine Tom

Journal of the American Chemical Society 2010 Volume 132(Issue 17) pp:5962-5963

Publication Date(Web):April 13, 2010

DOI:10.1021/ja101673v

A hydroxyl group-directed, highly regio- and stereoselective transposition of allylic alcohols based on rhenium catalysis has been developed. The method is suitable for a direct isomerization of acetals into the thermodynamically preferred isomer as long as one of the hydroxyl groups is allylic. This method will expand the scope of rhenium-catalyzed alcohol transpositions for complex molecule synthesis.

Total Synthesis of Rhazinilam: Axial to Point Chirality Transfer in an Enantiospecific Pd-Catalyzed Transannular Cyclization

Co-reporter:Zhenhua Gu and Armen Zakarian

Organic Letters 2010 Volume 12(Issue 19) pp:4224-4227

Publication Date(Web):August 26, 2010

DOI:10.1021/ol101523z

A total synthesis of rhazinilam based on a transannular cyclization strategy is described. Using a Heck reaction, the axial chirality of a halogenated 13-membered lactam can be exploited to create the quaternary chiral stereogenic center in the target molecule with high enantiospecificity.

Marine Toxins with Spiroimine Rings: Total Synthesis of Pinnatoxin A (Eur. J. Org. Chem. 30/2010)

Co-reporter:Stéphane Beaumont;Elizabeth A. Ilardi;Nicholas D. C. Tappin

European Journal of Organic Chemistry 2010 Volume 2010( Issue 30) pp:

Publication Date(Web):

DOI:10.1002/ejoc.201090082

Abstract

The cover picture shows the building blocks for the total synthesis of pinnatoxin A as the focal point, culminating with the marine natural product at the top of the stairs. The background reflects a highlight of the Santa Barbara Mission, located in Santa Barbara, California. Founded by Franciscan Friar Fermin de Lasuen on the Feast of St. Barbara in 1786, the mission is the principal cultural and historic landmark of the city. The spiral symbolizes the universal pattern of growth and evolution, as well as the ongoing process of discovery. Details of the total synthesis of pinnatoxin A are presented in the Microreview by A. Zakarian et al. on p. 3743 ff.

Marine Toxins with Spiroimine Rings: Total Synthesis of Pinnatoxin A

Co-reporter:Stéphane Beaumont;Elizabeth A. Ilardi;Nicholas D. C. Tappin

European Journal of Organic Chemistry 2010 Volume 2010( Issue 30) pp:5743-5765

Publication Date(Web):

DOI:10.1002/ejoc.201000842

Abstract

This microreview provides a compilation of synthetic approaches and total syntheses of pinnatoxin A in a survey of the literature up to early 2010. Pinnatoxin A is the first discovered and representative member of a fascinating group of potent marine toxins that share a spiroimine subunit as a unifying structural element.

Concise Total Synthesis of Sintokamides A, B, and E by a Unified, Protecting-Group-Free Strategy

Co-reporter:Dr. Zhenhua Gu ;Dr. Armen Zakarian

Angewandte Chemie International Edition 2010 Volume 49( Issue 50) pp:9702-9705

Publication Date(Web):

DOI:10.1002/anie.201005354

Concise Total Synthesis of Sintokamides A, B, and E by a Unified, Protecting-Group-Free Strategy

Co-reporter:Dr. Zhenhua Gu ;Dr. Armen Zakarian

Angewandte Chemie 2010 Volume 122( Issue 50) pp:9896-9899

Publication Date(Web):

DOI:10.1002/ange.201005354

[3,3]-Sigmatropic rearrangements: recent applications in the total synthesis of natural products

Co-reporter:Elizabeth A. Ilardi, Craig E. Stivala and Armen Zakarian

Chemical Society Reviews 2009 vol. 38(Issue 11) pp:3133-3148

Publication Date(Web):02 Sep 2009

DOI:10.1039/B901177N

Among the fundamental chemical transformations in organic synthesis, the [3,3]-sigmatropic rearrangement occupies a unique position as a powerful, reliable, and well-defined method for the stereoselective construction of carbon–carbon or carbon–heteroatom bonds. While many other reactions can unite two subunits and create a new bond, the strengths of sigmatropic rearrangements derive from their ability to enable structural reorganization with unmatched build-up of complexity. Recent applications that illustrate [3,3]-sigmatropic processes as a key concept in the synthesis of complex natural products are described in this tutorial review, covering literature from about 2001 through early 2009.

Consecutive sigmatropic rearrangements in the enantioselective total synthesis of (−)-joubertinamine and (−)-mesembrine

Co-reporter:Elizabeth A. Ilardi, Michael J. Isaacman, Ying-chuan Qin, Sommer A. Shelly, Armen Zakarian

Tetrahedron 2009 65(16) pp: 3261-3269

Publication Date(Web):

DOI:10.1016/j.tet.2008.10.048

Total Synthesis of ()-TrichodermamideB and of a Putative Biosynthetic Precursor to AspergillazineA Using an Oxaza-Cope Rearrangement

Co-reporter:Chong-Dao Lu Dr. Dr.

Angewandte Chemie 2008 Volume 120( Issue 36) pp:6935-6937

Publication Date(Web):

DOI:10.1002/ange.200801652

Total Synthesis of ()-TrichodermamideB and of a Putative Biosynthetic Precursor to AspergillazineA Using an Oxaza-Cope Rearrangement

Co-reporter:Chong-Dao Lu Dr. Dr.