Co-reporter:James A. Rossi-Ashton;Richard J. K. Taylor;William P. Unsworth
Organic & Biomolecular Chemistry 2017 vol. 15(Issue 36) pp:7527-7532
Publication Date(Web):2017/09/20
DOI:10.1039/C7OB02039B
Three divergent Direct Imine Acylation (DIA) procedures are reported that allow the selective generation of δ-lactams, β-lactams and tetrahydropyrimidinones (via a novel three-component coupling) from imine and carboxylic acid precursors. All operate via initial N-acyliminium ion formation and diverge depending on the reaction conditions and nature of the substrates.
Co-reporter:Aimee K. Clarke;John T. R. Liddon;James D. Cuthbertson;Richard J. K. Taylor;William P. Unsworth
Organic & Biomolecular Chemistry 2017 vol. 15(Issue 1) pp:233-245
Publication Date(Web):2016/12/20
DOI:10.1039/C6OB02426B
Two complementary dearomatising spirocyclisation protocols to generate spirocyclic dienones from anisole and phenol-tethered ynones are described, each proceeding via electrophilic alkyne activation. The first approach focuses on the spirocyclisation of para-substituted anisoles using either SnCl2·2H2O or Cu(OTf)2. The second approach, which enables the spirocyclisation of both ortho- and para-substituted phenols, uses silica-supported AgNO3 to generate similar scaffolds with much greater efficiency. Initial asymmetric studies are also outlined.
Co-reporter:Michael J. James, Niall D. Grant, Peter O’Brien, Richard J. K. Taylor, and William P. Unsworth
Organic Letters 2016 Volume 18(Issue 24) pp:6256-6259
Publication Date(Web):November 30, 2016
DOI:10.1021/acs.orglett.6b03017
A series of high-yielding silver(I)-catalyzed cyclization reactions of pyridine-, isoquinoline-, and pyrazine-ynones are described. The operationally simple and mild reaction conditions are a significant improvement over previously reported thermal cyclizations. The quinolizinone products were also used in a novel dearomatization strategy to prepare 0.53 g of the alkaloid lasubine II in five steps and 36% overall yield.
Co-reporter:John T. R. Liddon, Aimee K. Clarke, Richard J. K. Taylor, and William P. Unsworth
Organic Letters 2016 Volume 18(Issue 24) pp:6328-6331
Publication Date(Web):November 28, 2016
DOI:10.1021/acs.orglett.6b03221
The dearomatization of 2-haloindole precursors allows access to indoleninyl halides, a hitherto underexploited functional handle with broad synthetic utility. Indoleninyl iodides have been shown to react via three distinct modes: hydrolysis, nucleophilic substitution, and cross-coupling. This allows a broad array of functionalized spirocyclic indole derivatives to be generated from a common starting material. They are also useful precursors to functionalized quinolines following migratory rearrangement and subsequent derivatization reactions.
Co-reporter:Matthew G. Lloyd, Mariantonietta D'Acunto, Richard J. K. Taylor and William P. Unsworth
Organic & Biomolecular Chemistry 2016 vol. 14(Issue 5) pp:1641-1645
Publication Date(Web):17 Dec 2015
DOI:10.1039/C5OB02579F
A regio- and stereoselective one-pot C–H insertion/olefination protocol has been developed for the late stage installation of α-methylene-γ-butyrolactones into conformationally restricted cyclohexanol-derivatives. The method has been successfully applied in the total synthesis of eudesmanolide natural product frameworks, including α-cyclocostunolide.
Co-reporter:Thomas O. Ronson, Christiana Kitsiou, William P. Unsworth, Richard J.K. Taylor
Tetrahedron 2016 Volume 72(Issue 40) pp:6099-6106
Publication Date(Web):6 October 2016
DOI:10.1016/j.tet.2016.05.009
The use of Direct Imine Acylation (DIA) methodology for the total synthesis of pallimamine is described, with three different synthetic routes examined. The construction of three advanced δ-lactam precursors, all utilising DIA, is described, along with attempts to progress these compounds further, using three distinct desymmetrisation strategies, two involving alcohol-aryl coupling, and a third involving an unusual diastereoselective lactonisation.Figure optionsDownload full-size imageDownload as PowerPoint slide
Co-reporter:Michael J. James; Peter O'Brien; Richard J. K. Taylor ;Dr. William P. Unsworth
Chemistry - A European Journal 2016 Volume 22( Issue 9) pp:2856-2881
Publication Date(Web):
DOI:10.1002/chem.201503835
Abstract
This Review provides an in-depth account of the synthesis of spirocyclic indolenines. Over the last 77 years, a wide array of diverse synthetic methods has been developed in order to generate these synthetically useful and biologically important spirocyclic scaffolds. The main synthetic strategies discussed are grouped into three main categories, namely interrupted Fischer indolisations, dearomatisation reactions of indoles and condensation reactions. The historical background, common synthetic challenges, current state-of-the-art and future perspectives of this field are examined.
Co-reporter:Michael J. James, Rosa E. Clubley, Kleopas Y. Palate, Thomas J. Procter, Anthony C. Wyton, Peter O’Brien, Richard J. K. Taylor, and William. P. Unsworth
Organic Letters 2015 Volume 17(Issue 17) pp:4372-4375
Publication Date(Web):August 21, 2015
DOI:10.1021/acs.orglett.5b02216
A high-yielding, divergent approach to generate either spirocyclic indolenines or carbazoles from a common indole-tethered propargyl alcohol precursor is described, with mechanistic insight provided. Either product can be obtained upon treatment with different Ag(I) catalysts at rt. An unexpected hydration reaction to afford (±)-actinopolymorphol B is also reported.
Co-reporter:Christiana Kitsiou;Jordan J. Hindes;Phillip I'Anson;Paula Jackson;Thomas C. Wilson;Eleanor K. Daly;Hannah R. Felstead;Peter Hearnshaw ;Dr. William P. Unsworth
Angewandte Chemie 2015 Volume 127( Issue 52) pp:16020-16024
Publication Date(Web):
DOI:10.1002/ange.201509153
Abstract
Structurally diverse macrocycles and medium-sized rings (9–24 membered scaffolds, 22 examples) can be generated through a telescoped acylation/ring-expansion sequence, leading to the insertion of linear fragments into cyclic β-ketoesters without performing a discrete macrocyclization step. The key β-ketoester motif is regenerated in the ring-expanded product, meaning that the same sequence of steps can then be repeated (in theory indefinitely) with other linear fragments, allowing macrocycles with precise substitution patterns to be “grown” from smaller rings using the successive ring-expansion (SuRE) method.
Co-reporter:Christiana Kitsiou;Jordan J. Hindes;Phillip I'Anson;Paula Jackson;Thomas C. Wilson;Eleanor K. Daly;Hannah R. Felstead;Peter Hearnshaw ;Dr. William P. Unsworth
Angewandte Chemie International Edition 2015 Volume 54( Issue 52) pp:15794-15798
Publication Date(Web):
DOI:10.1002/anie.201509153
Abstract
Structurally diverse macrocycles and medium-sized rings (9–24 membered scaffolds, 22 examples) can be generated through a telescoped acylation/ring-expansion sequence, leading to the insertion of linear fragments into cyclic β-ketoesters without performing a discrete macrocyclization step. The key β-ketoester motif is regenerated in the ring-expanded product, meaning that the same sequence of steps can then be repeated (in theory indefinitely) with other linear fragments, allowing macrocycles with precise substitution patterns to be “grown” from smaller rings using the successive ring-expansion (SuRE) method.
Co-reporter:Matthew G. Lloyd, Mariantonietta D'Acunto, Richard J.K. Taylor, William P. Unsworth
Tetrahedron 2015 Volume 71(Issue 39) pp:7107-7123
Publication Date(Web):30 September 2015
DOI:10.1016/j.tet.2014.09.054
A system for the synthesis of α-alkylidene-γ-butyrolactones via a one-pot C–H insertion/olefination sequence is described. The process is based on the rhodium catalysed C–H insertion reaction of α-diazo-α-(diethoxyphosphoryl)acetates. The mild reaction conditions, operational simplicity and ready availability of starting materials are all key features. A wide range of successful reaction systems are reported (41 examples) highlighting the generality of the method. The application of this method in the total synthesis of the natural products (±)-cedarmycins A and B is also described.
Co-reporter:Matthew G. Lloyd, Richard J. K. Taylor, and William P. Unsworth
Organic Letters 2014 Volume 16(Issue 10) pp:2772-2775
Publication Date(Web):May 2, 2014
DOI:10.1021/ol501092m
A one-pot C–H insertion/olefination sequence for the conversion of α-diazo-α-(dialkoxyphosphoryl)acetates into α-alkylidene-γ-butyrolactones is reported. The key C–H insertion process is achieved using a catalytic amount of a dirhodium carboxylate catalyst, using operationally simple conditions. The size and electronic properties of the attached substituents were found to influence the regio- and diastereoselectivity of the process. The utility of the process is demonstrated by the synthesis of a known Staphylococcus aureus (MRSA) virulence inhibitor.
Co-reporter:William P. Unsworth, Christiana Kitsiou, and Richard J. K. Taylor
Organic Letters 2013 Volume 15(Issue 13) pp:3302-3305
Publication Date(Web):June 20, 2013
DOI:10.1021/ol4013469
The first total synthesis of the Evodia rutaecarpa derived natural product dievodiamine is described. The convergent synthesis was performed without protecting groups, delivering a route that is short and high yielding and uses limited chromatography. Key steps include organometallic addition into a DHED adduct and the Stille coupling of two advanced intermediates to complete the synthesis.
Co-reporter:William P. Unsworth, James D. Cuthbertson, and Richard J. K. Taylor
Organic Letters 2013 Volume 15(Issue 13) pp:3306-3309
Publication Date(Web):June 20, 2013
DOI:10.1021/ol4013958
The first total synthesis of spirobacillene A, an indole alkaloid isolated from Lysinibacillus fusiformis, is reported. A Lewis acid mediated spirocyclization of an anisole derivative onto a tethered ynone was used as a key step, drawing inspiration from a potential biosynthesis of the natural product.
Co-reporter:William P. Unsworth and Richard J. K. Taylor
Organic & Biomolecular Chemistry 2013 vol. 11(Issue 42) pp:7250-7261
Publication Date(Web):20 Aug 2013
DOI:10.1039/C3OB41519H
The complex macrocycle ‘upenamide was isolated in 2000, stimulating significant effort from synthetic chemists to complete its total synthesis and verify its structure. Progress made by several groups is detailed, culminating in the synthesis of both of the proposed structures of this unique natural product, neither of which matched the natural material according to spectroscopic analysis. The evolution of the synthetic route and the development of associated methodologies are described.
Co-reporter:William P. Unsworth and Richard J. K. Taylor
Organic & Biomolecular Chemistry 2013 - vol. 11(Issue 42) pp:NaN7261-7261
Publication Date(Web):2013/08/20
DOI:10.1039/C3OB41519H
The complex macrocycle ‘upenamide was isolated in 2000, stimulating significant effort from synthetic chemists to complete its total synthesis and verify its structure. Progress made by several groups is detailed, culminating in the synthesis of both of the proposed structures of this unique natural product, neither of which matched the natural material according to spectroscopic analysis. The evolution of the synthetic route and the development of associated methodologies are described.
Co-reporter:Matthew G. Lloyd, Mariantonietta D'Acunto, Richard J. K. Taylor and William P. Unsworth
Organic & Biomolecular Chemistry 2016 - vol. 14(Issue 5) pp:NaN1645-1645
Publication Date(Web):2015/12/17
DOI:10.1039/C5OB02579F
A regio- and stereoselective one-pot C–H insertion/olefination protocol has been developed for the late stage installation of α-methylene-γ-butyrolactones into conformationally restricted cyclohexanol-derivatives. The method has been successfully applied in the total synthesis of eudesmanolide natural product frameworks, including α-cyclocostunolide.
Co-reporter:Aimee K. Clarke, John T. R. Liddon, James D. Cuthbertson, Richard J. K. Taylor and William P. Unsworth
Organic & Biomolecular Chemistry 2017 - vol. 15(Issue 1) pp:NaN245-245
Publication Date(Web):2016/11/23
DOI:10.1039/C6OB02426B
Two complementary dearomatising spirocyclisation protocols to generate spirocyclic dienones from anisole and phenol-tethered ynones are described, each proceeding via electrophilic alkyne activation. The first approach focuses on the spirocyclisation of para-substituted anisoles using either SnCl2·2H2O or Cu(OTf)2. The second approach, which enables the spirocyclisation of both ortho- and para-substituted phenols, uses silica-supported AgNO3 to generate similar scaffolds with much greater efficiency. Initial asymmetric studies are also outlined.