Carbonium cyclization—studies on lignans containing the dibenzocyclooctadiene system,II |
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Authors: | Rui Tan Xiao-Tian Liang |
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Abstract: | Studies of schisandrol B under Ritter reaction conditions showed similar results to that of schisandrin. However the carbonium cyclization product (4a) of schisandrol B undergoes oxidative ring opening when exposed to the air. Cyclization of schisantherin A (2) also occurs by treatment with thionyl chloride in pyridine. Here the presence of the extra benzoyloxy group somehow confers stability to the diosphenol system and 8 has to be stirred in solution under oxygen for extended periods to effect ring opening. |
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