Synthesis of (+)-pechueloic acid and (+)-aciphyllene. Revision of the structure of (+)-aciphyllene
作者:Gonzalo Blay、Begoña Garcia、Eva Molina、José R. Pedro
DOI:10.1016/j.tet.2007.07.039
日期:2007.9
1 alpha H,7 alpha H,10 alpha H-Guaia-4,11-dien-3-one and its 1 beta H,10 beta H diastereomer, easily obtained from (+)-dihydrocarvone, are good starting materials for the synthesis of natural guaiane derivatives. Allylic oxidation of the 1 alpha H,10 alpha H isomer gave as main product its 13- hydroxy derivative and a small amount of (+)-7 beta-hydroxy-1 alpha H,10 alpha H-guaia-4,11-dien-3-one, whereas the 1 beta H, 10 beta H diastereomer afforded selectively the (-)-7 alpha-hydroxy-1 beta H,10 beta H enantiomer in excellent yield. From the 13-hydroxy derivative (+)-pechueloic acid and (+)-methyl pechueloate were synthesized. Deoxygenation at C-3 of the 1 beta H,10 beta H guaiadienone afforded a guaiadiene with the reported structure for aciphyllene but its spectral data did not agree with those reported for the natural diene. The structure of natural (+)-aciphyllene has been corrected to 1 alpha H,7 alpha H,10 alpha H-guaia-4,11-diene obtained by deoxygenation of the 1 alpha H,10 alpha H guaiadienone. (c) 2007 Elsevier Ltd. All rights reserved.