Synthesis of 1,1'-methylenedi[(1R,1'R,3R,3'R,5R,5'R)-8-oxabicyclo[3.2.1]oct-6-en-3-ol] and derivatives: precursors of long-chain polyketide

Racemic 1,1'-methylene[(1RS, 1'RS, 3RS, 3'RS, 5RS, 5'RS)-8-oxabicyclo[3.2.1]oct-6-en-3-ol] ((+/-)-6) derived from 2,2'-methylenedifuran has been resolved kinetically with Candida cylindracea lipase-catalysed transesterification giving 1,1'-methylenedi[(1R, 1'R, 3R, 3'R, 5R, 5'R)-8-oxabicyclo[3.2.1]oct-6-en-3-ol] (-)-6 (30% yield, 98% ee) and 1,1'-methylenedi[(1S, 1'S, 3S, 3'S, 5S, 5'S)-8-oxabicyclo[3.2.1]oct-6-en-3-yl] diacetate (+)-8, (40% yield, 98% ee). These compounds have been converted into 1,1'-methylenedi[(4S, 4'S, 6S, 6'S)- and (4R, 4'R, 6R, 6'R)-cyclohept-1-en-4,6-diyl] derivatives. (C) 2001 Published by Elsevier Science Ltd.