Bicyclo[2.2.1]heptanes in organic synthesis. Total synthesis of the 16-membered ring macrolide tylonolide hemiacetal: synthesis and coupling of the C(3)-C(9) and C(11)-C(17) fragments
We have succeeded in a highlystereoselective asymmetric Diels-Alder reaction between a chiral acrylate derived from commercially available D-pantolactone and 5-benzyloxymethyl-cyclopentadiene to give the adduct in 94% d.e. and 79% yield for the synthesis of Corey lactone .
Highly enantioselective synthesis of a Corey prostaglandin intermediate
作者:Baptiste Ronan、Henri B. Kagan
DOI:10.1016/s0957-4166(00)82318-6
日期:1992.1
give, after basic treatment, the bicyclic sulfoxide10 with very high de. This compound was transformed in three steps into enantiomerically pure norbornenone1, a key intermediate in some Corey syntheses of prostaglandins.
The bioconversion of 7-anti-benzyloxymethylbicyclo [2.2.1]hept-5-en-2-one 1 with cells of Acinetobacter calcoaceticus NCIB 9871 has been studied. Its (1R, 4S, 7R) enantiomer underwent a Baeyer-Villiger oxidation yielding rearranged lactone 2 (ee 85%), whereas (1S, 4R, 7S)-1 was reduced to alcohols 3-endo (ee 95%) and 3-exo (o.p. 89%).