Petasis boronic acid-Mannich reactions of substituted hydrazines: synthesis of α-hydrazino carboxylic acids

Published in: Journal, Volume : 43, Issue : 38, Pages : 6845-6847

DOI : 10.1016/s0040-4039(02)01511-3

Author : Portlock, David E.; Naskar, Dinabandhu; West, Laura; Li, Min

Abstract : R1CONHNHR2 [R1 = OCMe3, OCH2Ph, NH2; R2 = cyclohexylmethyl, Me2CHCH2, MeO2CCH2, PhCH2, Ph, 4-MeC6H4, 4-O2NC6H4,2-pyridyl, H, EtO2CCH2] can serve as amine substrates for the Petasis boronic acid-Mannich reaction with R3B(OH)2 [R3 = 4-MeOC6H4, 4-MeC6H4, PhCH:CH, Ph, 2-benzothienyl, 1-naphthyl] and OCHCO2H, providing a practical synthetic route for the preparation of α-hydrazinocarboxylic acids R1CONHNR2CHR3CO2H. The scope and limitations of this method have been examined

Solution phase synthesis of imidazo[1,2-b]pyrazol-2-one, an interesting 5,5-fused heterocyclic ring system

Published in: Journal, Volume : 45, Issue : 3, Pages : 619-621

DOI : 10.1016/j.tetlet.2003.10.177

Author : Blass, Benjamin E.; Srivastava, Anil; Coburn, Keith R.; Faulkner, Amy L.; Janusz, John J.; Ridgeway, James M.; Seibel, William L.

Abstract : The solution phase synthesis of a series of imidazo[1,2-b]pyrazol-2-ones, e.g., I, a fused 5,5-ring system, is described. The heterocyclization of α-hydrazino acids with α-cyano ketones gave 5-aminopyrazoles, e.g., II, which underwent an intramol. cyclodehydration to give the corresponding imidazo[1,2-b]pyrazol-2-ones.