| Abstract
| - Solvolysis of 4-alkoxycarbonyl-(or 4-acyl)-3-oxo-1,2,3,4-tetrahydroquinolizinium ylides (1−4) wasstudied and three types of reactions were found to proceed competitively. Thus, alcoholysis affordedthe Chichibabin rearrangement products, 2,3-dihydro-2-indolizinones (5−8), solvolysis in trifluoroethanol or in aqueous methanol caused ring opening (and subsequent ester cleavage) to2-alkoxycarbonylethylpyridinium-1-acetates 10, 15, and 16, and hydrolysis resulted in ring openingto 1-alkoxycarbonylmethylpyridinium-2-propionates 11 or 13 (and subsequently to 12 or 14).Characteristically, all the types of reactions proceeded significantly faster with t-butoxycarbonylsubstituted ylides than with smaller alkoxycarbonyl substituted ones. The general mechanism forthe solvolysis, involving a ketene intermediate, is proposed based on kinetic measurements.
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