Steven M. Allin

The preparation and first application of a polymer-supported "Evans" oxazolidinone

Abstract The preparation of a polymer-supported “Evans” oxazolidinone is described. and its use as a chiral auxiliary is demonstrated by the synthesis of a chiral α-alkyl carboxylic acid (e.e. 96%).

A facile and highly stereoselective approach to a polycyclic isoindolinone ring system via an N-acyliminium ion cyclization reaction

A highly diastereoselective synthesis of chiral ring-fused isoindolinone products, the skeleton of which is common to many naturally occurring and biologically active compounds, is achieved in only two synthetic steps from readily available precursors via an N-acyliminium ion cyclization reaction of an isoindolinone substrate.

Radical cyclisation onto pyrazoles: synthesis of withasomnine

Abstract A novel synthetic protocol for the synthesis of [1,2- b ]-fused bicyclic pyrazoles has been developed using radical cyclisation. The protocol uses cyclisation of pyrazole-1-(ω-alkyl) radicals generated from 1-[ω-(phenylselenyl)alkyl]-pyrazole precursors. The pyrazole natural product, withasomnine (3-phenyl-5,6-dihydro-4 H -pyrrolo[1,2- b ]pyrazole), and larger ring analogues have been synthesised in good yield using the protocol. A Bu 3 SnH-mediated oxidative cyclisation mechanism is facilitated by azo or Et 3 B radical initiators acting as oxidants of the intermediate π-radicals.

A highly diastereoselective synthesis of tricyclic lactams and their application as novel N-acyl iminium ion precursors in the synthesis of isoindolinone derivatives

Condensation of 2-formylbenzoic acid with α-amino alcohol substrates proceeds with extremely high diastereoselectivity to produce tricyclic γ-lactam products. The relative stereochemistry of the major diastereoisomer has been determined by X-ray crystal analysis and a mechanism suggested to explain the stereochemical outcome. Further, we report that this class of heterocycle can act as an N-acyl iminium ion precursor in the synthesis of substituted isoindolinone derivatives.

Synthesis and antimicrobial activity of some isoindolin-1-ones derivatives

A range of N-substituted isoindolin-1-ones was prepared and their potential as novel antimicrobial agents was investigated. MIC values for active compounds were determined and reported.

A highly diastereoselective synthesis of 3-substituted isoindolin-1-one dericatives

A highly diastereoselective method for the synthesis of 3-substituted isoindolin-1-ones has been developed through application of a tricyclic lactam substrate as an N-acyliminium ion precursor. Ring-opening of the tricyclic lactam with triethylsilane as hydride source generates the targets with up to exclusive levels of diastereoselectivity. This approach compliments that reported in the preceding paper.

A new approach to the synthesis of non-racemic isoindolin-1-one derivatives

A new approach for the synthesis of non-racemic 3-substituted isoindolin-1-one targets has been developed through application of a tricyclic γ-lactam substrate as an N-acyliminium ion precursor.

Asymmetric Epoxidation Using Iminium Salt Organocatalysts Featuring Dynamically Controlled Atropoisomerism

Introduction of a pseudoaxial substituent at a stereogenic center adjacent to the nitrogen atom in binaphthyl- and biphenyl-derived azepinium salt organocatalysts affords improved enantioselectivities and yields in the epoxidation of unfunctionalized alkenes. In the biphenyl-derived catalysts, the atropoisomerism at the biphenyl axis is controlled by the interaction of this substituent with the chiral substituent at nitrogen.

Stereoselective synthesis of the indolizinoindole ring system

We report a novel, facile and stereoselective approach to the indolizino[8,7-b]indole ring system from a readily available, non-racemic chiral template.

Diastereoselective electrophilic amination of ketone enolates in 2-substituted 2-acyl-1,3-dithiane 1-oxides

Abstract Enolate anions derived from 2-substituted 2-acyl-1,3-dithiane 1-oxides react readily with the nitrogen electrophile di- tert -butyl azodicarboxylate (DBAD) to give α-aminoketones with good diastereoselectivity and in reasonable yields; in some cases diastereoselectivity appears sufficiently high that the minor isomer cannot be detected by 400 MHz 1 H NMR spectroscopy.