The Olefination Reactions of Propargylic Dithioacetal
Date Issued
2008
Date
2008
Author(s)
Chen, Chih-Wei
Abstract
The new olefination methods of alkyl substituted propargylic dithioacetals are described in this thesis. It can be divided into two parts for discussions. n previous results, Alkyl substituted propargylic dithioacetals treating with butyl lithium then were allowed to react with carbonyl compounds to form homopropargylic alcohol with high yields and highly regioselective. This result showed different selsctivity comparing with aryl substituted propargylic dithioacetals. It seemed that different regioselectivies arose from different substiuents. Alkyl substituted ones were prefer to form homopropargylic alcohol and aryl ones were prefer to form allenyl alcohol.he first part, we used the mild Mitsunobu conditions transforming homopropargylic alcohol into corresponding enyne derivatives. Because of using Mitsunobu conditions, which have highly functional group tolerance, the strong reduction environments sensitive substituents, like bromine, ester, and cyano group, may go through the reaction smoothly. Even the protected alcohol moiety and dithioacetal moiety also can proceed in the reaction environments. The steoreselectiviy showed the E selectivity in most of cases and Z selectivity was presented in larger substituents like mesityl and 1-naphthyl. Further pretests of synthesizing polymers also showed the highly possibility of synthetic single molecular weigh polymers.he second part, we have developed a convenient and highly-regioselective approach to synthesis of trisubstituted iodofurans. Treating homoparpargylic alcohols with mercury acetate following with iodine reagent can be smooth converted to 2,4,5-trisubstituted iodofurans in moderate to good yields. The substituents on 2 and 4 position of furan ring were derived from the propargylic part of homopropargylic alcohol, and the substituent on 5 position of furan ring was derived from the
Subjects
propargylic dithioacetal
homopropargylic alcohol
Type
thesis
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