Stereoselective epoxidation of cyclic alkenes using m-CPBA and Oxone®/trifluoroacetone — A comparison
作者:Simon E. de Sousa、Peter O'Brien、Christopher D. Pilgram、Daniel Roder、Timothy D. Towers
DOI:10.1016/s0040-4039(98)02320-x
日期:1999.1
A comparison of the observed diastereoselectivity of epoxidation of cyclic alkenes using m-CPBA and Oxone®/trifluoroacetone is reported. The results indicate that dioxiraneepoxidations are sterically controlled and provide a crude model for determination of whether hydrogen bonding is operating in the m-CPBA epoxidations.
Synthesis and enantioselective rearrangement of 4-amino-substituted cyclopentene oxides
作者:Peter O'Brien、Timothy D. Towers、Matthias Voith
DOI:10.1016/s0040-4039(98)01821-8
日期:1998.10
Several N-mono- and diprotected alkenes have been prepared and the, stereoselectivity of their epoxidation has been investigated: N-monoprotected alkenes give cis epoxides preferentially (due to hydrogen bonding directed epoxidations) whereas N-diprotected alkenes produce trans epoxides exclusively (due to steric effects). Chiral lithium amide base-mediated rearrangement of a cis-monoprotected epoxide generated the corresponding amino-cyclopentenol in good yield and with an enantiomeric excess of 60%. (C) 1998 Elsevier Science Ltd. All rights reserved.
New Route to 4-Aminocyclopent-2-en-1-ols: Synthesis and Enantioselective Rearrangement of 4-Amino-substituted Cyclopentene Oxides
作者:Stephen Barrett、Peter O'Brien、H.Christian Steffens、Timothy D Towers、Matthias Voith
DOI:10.1016/s0040-4020(00)00911-x
日期:2000.12
nucleoside analogue synthesis is described. The approach involves the stereoselective preparation of cis 4-amino-substituted cyclopentene oxides and subsequent chiral base-mediated rearrangement to the corresponding allylic alcohols. Full details on the synthesis and stereoselectivity of epoxidation of 4-amino-substituted cyclopentenes are presented.
Synthesis and reactions of cyclopentadiene monoaziridine: a concise approach to the core of agelastatin A
作者:Elise Baron、Peter O'Brien、Timothy D Towers
DOI:10.1016/s0040-4039(01)02238-9
日期:2002.1
protocol for the preparation of cyclopentadiene monoaziridine is described (88% yield). The utility of cyclopentadiene monoaziridine is demonstrated by its use in (i) the shortest synthetic entry into 4-amino substituted cyclopentenes and (ii) the preparation of two key intermediates in a concise synthetic approach to the cyclopentane core of agelastatin A. The agelastatin A model studies make use of a