Ring Transformation by Ring Chain Transfer VI1: Regioselective Synthesis of (ω-Aminoalkyl)pyrazoles from Semicyclic 3-Chloro-2-propeniminium Salts and Hydrazines
(ω-Ammonioalkyl)cyclopentadienides by Rhodium-Catalyzed Vinylcarbene Transfer to Semicyclic Enaminocarbonyl Compounds
作者:Gerhard Maas、Andreas Müller
DOI:10.1021/ol990546u
日期:1999.7.1
The rhodium(ll) catalyzed reaction of vinyldiazoacetate 2 with semicyclic beta-enaminocarbonyl compounds 1 provides (omega-(methylammonio)-alkyl)cyclopentadienides 3. This transformation represents a novel reaction cascade which combines carbenoid addition at a C=C bond with ring chain transformation. In some cases, products resulting from vinylcarbene insertion into the enaminic C-H bond of 1 are also isolated, These dienamines undergo subsequent isomerization to furnish betaines 3.
作者:Bohrish, Joerg、Paetzel, Michael、Liebscher, Juergen、Jones, Peter G.、Chrapkowski, A.
DOI:——
日期:——
Ring Transformation by Ring Chain Transfer VI<sup>1</sup>: Regioselective Synthesis of (ω-Aminoalkyl)pyrazoles from Semicyclic 3-Chloro-2-propeniminium Salts and Hydrazines
Novel semicyclic 3-aryl-3-chloro-2-propeniminium perchlorates 6 are synthesized by treating semicyclic enaminones 1 (2-aroylmethylene-1-methylpyrrolidines, -piperidines and -azepanes) with phosphoryl chloride dimethylformamide. Reaction of these chloropropeniminium salts 6 with hydrazines 2 give regiospecifically either 3-(Ï-aminoalkyl)- or 5-(Ï-aminoalkyl)pyrazoles 5 or 10. The direction of these ring transformation reactions is governed by the nature of substituent of the hydrazine. The synthesis is especially useful in the preparation of 1-substituted 5-(Ï-aminoalkyl)pyrazoles 10.