Date Published: Friday, August 13, 2010
Molecules 2010, 15 (8), 5595-619.
Authors: Sharma, P. K.; He, M.; Jurayj, J.; Gou, D. M.; Lombardy, R.; Romanczyk, L. J., Jr.; Schroeter, H.
The first enantioselective syntheses of sulfur flavan-3-ol analogues 1-8 have been accomplished, whereby the oxygen atom of the pyran ring has been replaced by a sulfur atom. The key steps were: (a) Pd(0) catalyzed introduction of -S t-butyl group, (b) Sharpless enantioselective dihydroxylation of the alkene, (c) acid catalyzed ring closure to produce the thiopyran ring, and (d) removal of benzyl groups using N,N-dimethylaniline and AlCl(3). The compounds were isolated in high chemical and optical purity.