Reactions of Amines and Hydrazides derived from L-Proline with Dialkyl Dicyanofumarates

Abstract

The reaction of prolinamine derivatives (8a,b) and dialkyl dicyanofumarates (1) in dichloromethane at room temperature leads to the optically active enamines (10). Whereas products (10) in the case of 1-benzyl prolinamine (8a) are stable compounds, the corresponding enamines obtained from the non-protected prolinamine (8b) smoothly undergo a cyclocondensation at room temperature to give perhydropyrrolo[1,2-a]pyrazine derivatives (11). The molecular structure of 11a was established by X-Ray crystallography. In analogy to 8a, 1-benzyl prolinehydrazide (9a) and 1b in dichloromethane react to yield the enehydrazine (12b). On the other hand, the reaction of 9a and 1 in methanol at room temperature leads to the corresponding dialkyl 3-amino-1H-pyrazole- 4,5-dicarboxylates (13) and methyl 1-benzylprolinate (14b) via a stepwise mechanism. The analogous reaction was observed between a 3-oxidoimidazole-4- carbohydrazide (15) and 1b.