4-Aryl-5-methyl-3-pyrrolin-2-ones

Treatment of esters of aromatic acids with l-alkyl-2-pyrrolidones and l-methyl-2-piperidones is an useful method for the preparation of simple pyrrolines and piperidines, respectively. The l-alkyl-3-aroyl-2-pyrrolidones (110, n = 1) and l-alkyl-3-aroyl-2-piperidones (110, n = 2) thus formed are cleaved by the action of concentrated hydrochloric acid to give l-methyl-2-aryl-2-pyrrolines453 (111, n = 1) and l-alkyl-2-aryl-2-piperidines454 (111, n = 2), respectively. After blocking the secondary nitrogen atom in a lactam by means of acylation, one can prepare 2-aryl-1-pyrrolines (112, n = 1) and 2-aryl-1 -piperidines4 55-457 (112, n = 2). 

Nitrogen Heterocycles.- Intramolecular Wittig reactions have been used to construct heterocyclic rings in, for example, the synthesis of N-alkyl-3-pyrrolines (193) (Scheme 18) and that of 2-methyl-3-(aryl/alkyl)-l-oxo-l,2-dihydroisoquinolines (195) by a one-pot synthesis from the amides (194) (Scheme 19). ... 

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