Oxabicyclo[3.2.1]octenes in organic synthesis: direct ring opening of oxabicyclo[3.2.1] ring systems with diisobutylaluminum hydride and a silyl ketene acetal--synthesis of the chiral C(19)-C(26) and C(27)-C(32) fragments of Scytophycin C.

[reaction: see text] An efficient strategy for transforming meso-oxabicyclo[3.2.1]octenone 1 into optically active intermediates for macrolide synthesis has been developed. The direct bridgehead opening of optically active oxabicyclo[3.2.1]octene derivative 2 with hydride or a silyl ketene acetal utilizing the highly polar medium lithium perchlorate in diethyl ether resulted in highly functionalized cycloheptenones, which were transformed into the C(19)-C(26) and C(27)-C(32) fragments of Scytophycin C.