| Summary: | 碩士 === 國立中央大學 === 化學學系 === 101 === This study is aimed to achieve the synthesis of Brevipolide. So far, the key intermediate III.8 was prepared in 7 steps with an overall yield of 18%. Michael-Initiated Ring Closure reactions were the key step to provide the cyclopropane moiety with diastereoselectivity. The facial selectivity was different for the substrates with different hydroxyl protecting groups, i.e. the TBS- and MOM-protected alfa,beta-unsaturated ketone gave the major R,R-cyclopropane (dr, 6.2:1), on the other hand, the acetonide-protected ketone provided the S,S-cyclopropane (dr, 1:2.4). The stereo-assignment of the R,R-cyclopropane was confirmed by the X-ray crystallography of the subsequent MOM-deprotected product III.9.
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