Acyclic Stereoselection in the Ortho Ester Claisen Rearrangement.
The ortho ester Claisen rearrangement of trisubstituted allylic alcohols exhibits significant levels of diastereoselection. In E allylic alcohols, a 1,3-diaxial interaction develops in the chairlike transition state leading to the anti isomer, rendering the reaction syn selective by a factor of 3-5 to 1. In Z allylic alcohols, the 1,3-diaxial interaction develops in the transition state leading to the syn isomer, generating an anti:syn selectivity of 6-15 to 1. The relative stereochemistry of the syn isomer was confirmed independently by the synthesis of the mycotoxin botryodiplodin.
Daub
G. William
GW
Department of Chemistry, Harvey Mudd College, Claremont, California 91711.
Edwards
James P.
JP
Okada
Carol R.
CR
Allen
Jana Westran
JW
Maxey
Claudia Tata
CT
Wells
Matthew S.
MS
Goldstein
Alexandra S.
AS
Dibley
Michael J.
MJ
Wang
Clarence J.
CJ
Ostercamp
Daniel P.
DP
Chung
Steven
S
Cunningham
Paula Shanklin
PS
Berliner
Martin A.
MA