title: Enantiospecific synthesis of carbapentostatins.
abstract: In this paper we describe enantioselective syntheses of (+)-carbapentostatin (8) and its cyclopentyl analogue 12b. A new and efficient one-pot, two-step preparation of aldehyde 15 has been developed, based on the borane reduction of N-Pf-protected L-aspartic acid gamma-methyl ester (13) and Swern oxidation of the resulting alcohol. Homologation to diester 18 and ring formation by Dieckman cyclization, followed by reduction and dehydration steps, afford the 4-amino-1-cyclopentenemethanol derivative 22. Hydroboration and oxidation transform this compound stereospecifically into aminocyclopentanol 26, the key aminocyclitol component for an asymmetric synthesis of (+)-carbapentostatin.
authors.affiliation: Department of Chemistry, University of California, Berkeley, California 94720, USA. jonathan_ho@merck.com
authors.forename: Jonathan Z
authors.initials: JZ
authors.lastname: Ho
authors.forename: Rafat M
authors.initials: RM
authors.lastname: Mohareb
authors.forename: Jin Hee
authors.initials: JH
authors.lastname: Ahn
authors.forename: Tae Bo
authors.initials: TB
authors.lastname: Sim
authors.forename: Henry
authors.initials: H
authors.lastname: Rapoport
mesh_terms: D003070:Coformycin / Q000737:chemistry; D020650:Combinatorial Chemistry Techniques; D003500:Cyclization; D015394:Molecular Structure; D015649:Pentostatin / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: C474412:carbapentostain; D003070:Coformycin; D015649:Pentostatin