Derivatives of heterocyclic α-iminocarboxylic acids 2. Conversion of hydrazides of heterocyclic α-iminocarboxylic acids into condensed bicyclic systems

By the interaction of hydrazides of L-proline, L-thioproline, pipecolic acid, and tetrahydro-1,4-thiazine-3-carboxylic acid with an excess of a carbonyl compound, through a stage of hydrazone formation, the following compounds have been obtained: 2,3-substituted 1,3-diazabicyclo[3.3.0]octan-4-ones; 7,8-substituted 7-thia-1,7-diazabicyclo[3.3.0]octan-6-ones; and 8,9-substituted diazabicyclo[4.3.0]nonan-7-ones. Preferential translinkage of the rings is characteristic for these heterocycles in solutions; if the substitution is asymmetric, the E-isomers are predominant.