Robert K. Boeckman

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Name: Robert K. Boeckman, Jr.; Robert K. Boeckman, Jr.

Organization: University of Rochester , USA

Department: Department of Chemistry

Title: Professor(PhD)

TOPICS

Organic Chemistry

Chemicals
References

A Scalable Total Synthesis of (−)-Nakadomarin A

Co-reporter:Robert K. Boeckman Jr., Hui Wang, Kyle W. Rugg, Nathan E. Genung, Ke Chen, and Todd R. Ryder

Organic Letters 2016 Volume 18(Issue 23) pp:6136-6139

Publication Date(Web):November 11, 2016

DOI:10.1021/acs.orglett.6b03137

The convergent total synthesis of the manzamine alkaloid (−)-nakadomarin A (1) is described. The retrosynthetic analysis recognized spirocycle 3, assembled via an organocatalyst-promoted Michael addition/cyclization between bicyclic lactam 4 and furan aldehyde 5, both accessible from achiral starting materials and on a multigram scale. Lactam 4 is assembled through an SN2′/reduction/Staudinger/retro-aza-Claisen sequence on scale. After spirocyclization, the synthesis of nakadomarin is completed in only six steps.

Organocatalytic Enantioselective α-Hydroxymethylation of Aldehydes: Mechanistic Aspects and Optimization

Co-reporter:Robert K. Boeckman Jr., Kyle F. Biegasiewicz, Douglas J. Tusch, and John R. Miller

The Journal of Organic Chemistry 2015 Volume 80(Issue 8) pp:4030-4045

Publication Date(Web):March 20, 2015

DOI:10.1021/acs.joc.5b00380

Further studies of the direct enantioselective α-hydroxymethylation of aldehydes employing the α,α-diarylprolinol trimethylsilyl ether class of organocatalysts are described. This process has proven efficient for access to β-hydroxycarboxylic acids and δ-hydroxy-α,β-unsaturated esters from aldehydes in generally good yields, excellent enantioselectivity, and compatibility with a broad range of functional groups in the aldehyde. The goal of these studies was to identify the critical reaction variables that influence the yield and enantioselectivity of the α-hydroxymethylation process such as catalyst structure, pH of the medium, purity of the reactants and reagents particularly with respect to the presence of acidic impurities, and the nature of the buffer, along with the standard variables including solvent, time, temperature and mixing efficiency. The previously identified intermediate lactol has been further characterized and its reactivity examined. These studies have led to identification of the most critical variables translating directly into improved substrate scope, reproducibility, enantioselectivity, and yields.

Total synthesis of a possible specific and effective acid-targeted cancer diagnostic, a camphor derived bis-N-oxide dimer

Co-reporter:Robert K. Boeckman Jr., Yan Miller, Dennis Savage, James E. Summerton

Tetrahedron Letters 2011 Volume 52(Issue 17) pp:2243-2245

Publication Date(Web):27 April 2011

DOI:10.1016/j.tetlet.2011.01.028

Possible specific and effective acid-targeted cancer diagnostics and therapeutics, a camphor derived bis-N-oxide dimer was synthesized in 12-steps from commercially available (+)-camphoric acid and seven-steps from a common intermediate, a camphor derived primary amine.

Studies culminating in the total synthesis and determination of the absolute configuration of (−)-saudin

Co-reporter:Robert K. Boeckman Jr., Maria Rico del Rosario Ferreira, Lorna H. Mitchell, Pengcheng Shao, Michael J. Neeb, Yue Fang

Tetrahedron 2011 67(51) pp: 9787-9808

Publication Date(Web):

DOI:10.1016/j.tet.2011.09.067

Diels−Alder Reactions of Cyclic Isoimidium Salts

Co-reporter:Robert K. Boeckman Jr., Yan Miller, and Todd R. Ryder

Organic Letters 2010 Volume 12(Issue 20) pp:4524-4527

Publication Date(Web):September 15, 2010

DOI:10.1021/ol101831b

Diels−Alder reactions of cyclic isoimidium salts are described. The corresponding cycloadducts are obtained with high regio- and stereoselectivity. The use of homochiral cyclic isoimidium salts delivers cycloadducts with excellent diastereoselectivity (>99:1) that can be efficiently converted to enantiomerically pure lactones.

Synthetic and Mechanistic Studies of the Aza-Retro-Claisen Rearrangement. A Facile Route to Medium Ring Nitrogen Heterocycles

Co-reporter:Robert K. Boeckman Jr., Nathan E. Genung, Ke Chen and Todd R. Ryder

Organic Letters 2010 Volume 12(Issue 7) pp:1628-1631

Publication Date(Web):March 10, 2010

DOI:10.1021/ol100397q

An efficient synthesis of medium-sized heterocyclic rings was achieved using a one-pot aza-Wittig/retro-aza-Claisen sequence of vinyl cyclobutanecarboxaldehydes derived from simple allylic carbonates. The use of various Staudinger reagents in the aza-Wittig reaction allows for a variety of N-substituted products to be obtained. The rearrangement is under thermodynamic control driven by relief of the cyclobutane ring strain and resonance stabilization of the resulting vinylogous amide/sulfonamide.

Direct Enantioselective Organocatalytic Hydroxymethylation of Aldehydes Catalyzed by α,α-Diphenylprolinol Trimethylsilyl Ether

Co-reporter:Robert K. Boeckman Jr. and John R. Miller

Organic Letters 2009 Volume 11(Issue 20) pp:4544-4547

Publication Date(Web):September 16, 2009

DOI:10.1021/ol9017479

The direct enantioselective hydroxymethylation of aldehydes utilizing α,α-diphenylprolinol trimethylsilyl ether as an organocatalyst is described. The intermediate α-substituted β-hydroxyaldehydes were not isolated but converted to the more readily isolable derivatives. For example, the derived hydroxy acids were isolated in up to 94% yield with excellent enantioselectivity.

The Development of a Convergent and Efficient Enantioselective Synthesis of the Bengamides via a Common Polyol Intermediate

Co-reporter:Robert K. Boeckman, Jr.;Tammy J. Clark;Brian C. Shook

Helvetica Chimica Acta 2002 Volume 85(Issue 12) pp:4532-4560

Publication Date(Web):2 JAN 2003

DOI:10.1002/hlca.200290026

An efficient, general synthetic route to the bengamide family of antitumor agents from a common polyol thioester is described. Consecutive aldol condensations afford the protected polyol thioester side chain suitable for coupling to the bengamides. A novel chiral-phase-transfer-catalyzed enantioselective alkylation affords the properly functionalized caprolactams required for the synthesis of more-complex members of the bengamide family. Use of the methyl 2-naphthyl ether protecting group, compatible with the boron Lewis acids required for enantioselective aldol condensation, allows direct access to all the bengamides.

PaaSiCats: Novel polyamino acid catalysts

Co-reporter:Anupma Dha;Karl-Heinz Drauz;Thomas Geller;Stanley M. Roberts

Chirality 2000 Volume 12(Issue 5‐6) pp:313-317

Publication Date(Web):19 MAY 2000

DOI:10.1002/(SICI)1520-636X(2000)12:5/6<313::AID-CHIR3>3.0.CO;2-H

The abilities of five polyamino acids (Paa's) to catalyse the asymmetric epoxidation of enones 1–7 under three sets of reaction conditions were compared: polyneo-pentylglycine and polyleucine showed distinct advantages in most circumstances. All five polymers were adsorbed onto silica and from this further study, immobilised polyneo-pentylglycine (PLNSi) and polyleucine (PLLSi) were shown to be the catalysts of choice for the asymmetric epoxidation of less-reactive α,β-unsaturated ketones. Chirality 12:313–317, 2000. © 2000 Wiley-Liss, Inc.