Optically active allene-1,3-dicarboxylates (1a and 2a), which contain the axial asymmetry of the allene moiety, were prepared. The Diels-Alder reaction of 1a and 2a with cyclopentadiene afforded the 1:1 (1a or 2a to cyclopentadiene) endo adducts 3a and 4a through the combination of the sterically favorable approach of the diene and the dienophile owing to the axial asymmetry of the allene moiety and the effective secondary orbital interaction. The absolute configurations of 3a and 4a were determined by chemical transformation and X-ray analysis. The absolute configuration of the axial asymmetry of la was also determined to be R by X-ray analysis.
Access to an optically pure cyclosarkomycin by conversion of the endo adduct of (R)-allene 1,3-dicarboxylate and cyclopentadiene
作者:Izumi Ikeda、Ken Kanematsu
DOI:10.1039/c39950000453
日期:——
The enantioselective synthesis of (–)-cyclosarkomycin is accomplished using the endo 1:1 adduct of (R)-allene 1,3-dicarboxylate and cyclopentadiene.
Optically active (R)- and (S)- allene-1,3-dicarboxylates were prepared, and their asymmetric Diels-Alderreactions with cyclopentadiene in the presence of Lewis acid proceeded to afford the endo-adducts in high yields.