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Synthesis of Methyl 5-Aryl-3-oxo-4-pentenoates and Novel Substituted Cyclopentenones
20 August 2002 (online)
The cinnamoyl- (1a-j) and (5-phenyl-2,4-pentadienoyl)- (1k) ketene dithioacetals are shown to undergo methanolysis in the presence of ether-boron trifluoride complex and mercury(II) chloride to the corresponding methyl 5-aryl-3-oxo-4-pentenoates 2a-j and 3-oxo-7-phenyl- 4,6-heptadienoate (2k), respectively, in good yields. However, the corresponding (2-methylcinnamoyl)ketene dithioacetals 3a-f, under identical reaction conditions, undergo Nazarov cyclization to give the corresponding substituted cyclopentenones 4a-f.