title: Synthesis of Unit A of Cryptophycin via a [2,3]-Wittig Rearrangement.
abstract: The synthesis of unit A of the cryptophycins from (S)-trans-3-penten-2-ol and from (S)-trans-4-hexen-3-ol has been completed. The key stereodetermining step is a [2,3]-Wittig rearrangement of a propargyl ether. Elaboration of the rearrangement product was accomplished by means of a selective hydroboration-oxidation of a terminal alkyne, Horner-Emmons homologation of the derived aldehyde, followed by selective ozonolytic cleavage and Wittig olefination. This synthesis provides easy access to the series of cryptophycin analogues that incorporate a modified aromatic ring in unit A.
authors.affiliation: Chemical Process Research and Development, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, and Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822.
authors.forename: Jian
authors.initials: J
authors.lastname: Liang
authors.forename: David W.
authors.initials: DW
authors.lastname: Hoard
authors.forename: Vien Van
authors.initials: VV
authors.lastname: Khau
authors.forename: Michael J.
authors.initials: MJ
authors.lastname: Martinelli
authors.forename: Eric D.
authors.initials: ED
authors.lastname: Moher
authors.forename: Richard E.
authors.initials: RE
authors.lastname: Moore
authors.forename: Marcus A.
authors.initials: MA
authors.lastname: Tius