The first preparation of enantiopure 1-methyl-7-oxabicyclo[2.2.1]heptan-2-one, a versatile chiral building block for terpenoids.
Methods for the resolution of (+/-)-1-methyl-7-oxabicyclo[2.2.1]heptan-2-one 1, a versatile chiral building block for terpenoids, have been investigated. While no efficient result was obtained with kinetic resolution methods, both enantiomers of 1 were prepared optically pure for the first time via esterification of the reductive products of 1 with (+)-mandelic acid and oxidation of the saponified products of diastereomer esters, in an overall yield of 70%. The absolute configurations of (-)-1 and (+)-1 were determined as (1S,4R)-(-)-1 and (1R,4S)-(+)-1 by the CD exciton chirality method and confirmed by Moshers (1)H-NMR method.
Guan
Yu-Kun
YK
State Key Laboratory of Applied Organic Chemistry, and Institute of Organic Chemistry, Lanzhou University, Lanzhou, Gansu 730000, P.R. China.
Li
Yu-Lin
YL