Synthetic studies on terpenic compounds—XI : Stereospecific total synthesis of portulal, |
| |
Authors: | Takashi Tokoroyama Keizo Matsuo Hiyoshizo Kotsuki Reizo Kanazawa |
| |
Affiliation: | Faculty of Science, Osaka City University, Sumiyoshi-ku, Osaka 558, Japan. |
| |
Abstract: | A stereospecific total synthesis of portulal 1 has been accomplished starting from the Diels-Alder adduct 2 from chloromethylmaleic anhydride and 1-vinylcyclohexene. Firstly 2 was converted by an efficient sequence of reactions to perhydroazulenoid lactone 5, which possesses the correct relative configuration with respect to three chiral centers out of the four present in 1. The fourth chiral center at C-6 was introduced stereospecifically together with the one-carbon substituent at C-4 by the ring formation between C-4 and C-6, and its cleavage to give an exomethylene lactone 35. At this stage the stereochemical validity of the crucial intermediate 35 was confirmed by chemical correlation with the hydroxy lactone 37 which was derived from natural 1 through a systematic degradation. Then 35 was transformed to 37 and the synthesis continued further by using 37 as a relay compound to afford 1. |
| |
Keywords: | Present address: Faculty of Pharmaceutical Sciences Kinki University Higashiosaka-shi Osaka 577 Japan. |
本文献已被 ScienceDirect 等数据库收录! |