title: Asymmetric synthesis of substituted 1-aminocyclopropane-1-carboxylic acids via diketopiperazine methodology.
abstract: Diketopiperazinespirocyclopropane 12 is prepared in > 98% d.e. via the conjugate addition of a phosphorus ylide to (6S)-N,N'-bis(p-methoxybenzyl)-3-methylenepiperazine-2,5-dione 2. Deprotection and hydrolysis of adduct 12 and subsequent peptide coupling demonstrate the applicability of this methodology to the asymmetric synthesis of 1-aminocyclopropane-1-carboxylic acids for incorporation into novel peptides. A model for the high level of diastereofacial selectivity observed in the cyclopropanation reaction is presented. A highly selective asymmetric approach (> 98% d.e.) to (S)-[2,2-(2)H2]-1-aminocyclopropane-1-carboxylic acid 29 is also reported via a deuterated sulfur ylide addition to acceptor 2.
authors.affiliation: Dyson Perrins Laboratory, University of Oxford, South Parks Road, Oxford, UK OX1 3QY.
authors.forename: Elena
authors.initials: E
authors.lastname: Buñuel
authors.forename: Steven D
authors.initials: SD
authors.lastname: Bull
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Davies
authors.forename: A Christopher
authors.initials: AC
authors.lastname: Garner
authors.forename: Edward D
authors.initials: ED
authors.lastname: Savory
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Smith
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Vickers
authors.forename: David J
authors.initials: DJ
authors.lastname: Watkin