Premium
Michael addition of N ‐isobutylidene‐ t ‐butylamine to dimethyl methoxymethylenemalonate and a new synthesis of some fused pyrazole derivatives from the adduct
Author(s) -
Ito Kunio,
Ihara Shogo,
Miyajima Shingo
Publication year - 1993
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570300613
Subject(s) - chemistry , michael reaction , adduct , substituent , pyrazole , alkylation , base (topology) , addition reaction , butylamine , medicinal chemistry , organic chemistry , amine gas treating , catalysis , mathematical analysis , mathematics
N ‐Isobutylidenemethylamine reacted with dimethyl methoxymethylenemalonate to afford the N ‐alkylation product 3a exclusively. Exchanging the N ‐substituent of the Schiff's base from methyl to t ‐butyl altered the course of the reaction, allowing Michael addition to take place predominantly. The Michael adduct 4c on reaction with hydrazinoalkanols 6a,b, 6c,d and 6e gave tetrahydropyrazolo[5,1‐ b ]oxazoles 9a,b , tetrahydro‐pyrazolo[5,1‐ b ][1,3]oxazines 9c,d and hexahydropyrazolo[5,1‐ b ][1,3]oxazepine 9e , respectively.