TOTAL SYNTHESIS OF(+)-1893B AIMED AT ESTABLISHING ITS STEREOCHEMISTRY*

摘要

The total synthesis of(+)-1893B(2)has been completed.The one-pot ring-opening/cross/ring-closing metathesis of(1S,2S,35,4R)-2-(r-butyldiphenylsilyloxy)methyl-3-methyl-7-oxabicyclo[2.2.1 ]hept-5-ene(4)provided(lR,6S,7S,8S)-7-hydroxymethyl-8-methyl-9-oxabicyclo[4.2.1]nona-2,4-diene(6)after deblocking.The epoxy-ring opening of an advanced intermediate(1R,6S,7S,8S)-7-[( 1 S,2S)-1-methoxymethoxy-2,3-epoxypropyl]-8-methyl-9-oxabi cyclo[4.2.1]nona-2,4-diene(11a)with trimethylsilylacetylide,followed by palladium(II)-catalyzed oxidation for construction of the gamma-lactone moiety in 2.