A One-Step Transformation of (S)-1-Benzoyl-3[(E)-dimethylaminomethylidene]-5-methoxycarbonylpyrrolidin-2-one into Quinolizinyl- and 2H-2-Pyranonyl-substituted Alanine Derivatives

~-l-Benzoyl-3-[(E)-dimethylaminomethylidene]-5-methoxycarbonylpyrrolidin-2-one (1) was transformed in one step with various 1,3dinucleophiles (2-14) into the corresponding N-benzoyl-3-quinolizinyl-(15-18) and N-benzoyl-3-(2H-2-pyranony1)alanine methyl esters (19-27).Due to their occurrence in nature, biological activity, and synthetic utility, there has been in the last few decades a significant interest for the synthesis of 3-heter~arylalanines.~Among various synthetic approaches, transformations of commercially available a-amino acids, such as serine, aspartic acid, and glutamic acid, are often used for the preparation of 3-heteroa~ylalanines.~Among them, only few preparations of pyranonylalanines have been reported.3Recently, Young and coworkers reported on the synthesis of 3-pyrazolyl-, 3-isoxazolyl-, and 3-pyrimidinylalanines from (8-3-formylpyroglutamic acid derivatives, using a 'ring switching' strategy.4On the other hand, we have previously shown that 3dimethylaminopropenoates can serve as versatile reagents for the preparation of a variety of heterocyclic systems.5-7In continuation of our work in this field, we report on efficient, one step synthesis of novel Nbenzoyl-3-heteroalylalanine esters (15-27) from easily available (9-1-benzoyl-3-[(Qdimethylaminomethylidene]-5-methoxycarbonylpyrrolidin-2-one (I) and by using an improved 'ring switching' strategy.The starting compound, (J~-l-benzoyl-3-[(E)-dimethylaminomethylidene]-5-methoxycarbonylpyrrolidin-2-one (I), was prepared from L-pyroglutamic acid in three steps according to the procedure described previously.7This was then treated with two types of I,?-dinucleophiles: 2-(pyridinyl-2)acetic acid derivatives (2-5) and carbocyclic and heterocyclic 1,3-dicarbonyl compounds and their analogs (6-14).Treatment of 1 with C,N-dinucleophiles (2-5) afforded quinolizinyl substituted alanine esters (15-18),For recent publications see: