33294-81-4Relevant articles and documents
Novel stereocontrolled approach to conformationally constrained analogues of L-glutamic acid and L-proline via stereoselective cyclopropanation of 3,4-didehydro-L-pyroglutamic ABO ester
Oba, Makoto,Nishiyama, Naohiro,Nishiyama, Kozaburo
, p. 8456 - 8464 (2007/10/03)
A new stereocontrolled approach to l-(carboxycyclopropyl)glycines (l-CCGs) and 3,4-methano-l-prolines, conformationally constrained analogues of l-glutamic acid and l-proline, respectively, was developed using a 3,4-didehydro-l- pyroglutamate derivative as a common chiral template. The unsaturated l-pyroglutamate derivative employed in this work is a novel chiral synthon in which the carboxyl functionality is protected as a 2,7,8-trioxabicyclo[3.2.1] octyl group (ABO ester). Stereospecific cyclopropanation of the olefin using diazomethane followed by appropriate functional group interconversion gave l-CCG-III and trans-3,4-methano-l-proline with complete stereocontrol. Synthesis of other diastereomers of l-CCG and cis-3,4-methano-l-proline was accomplished by alteration of the 3,4-methanoglutamic acid framework via carboxycyclopropanation of the olefin with sulfur ylide and subsequent Barton decarboxylation reaction of the original γ-carboxyl group included in the pyroglutamate skeleton.
