99017-77-3Relevant academic research and scientific papers
Microwave-assisted solution-phase synthesis of 1,4,5-trisubstituted pyrazoles
Giacomelli, Giampaolo,Porcheddu, Andrea,Salaris, Margherita,Taddei, Maurizio
, p. 537 - 541 (2007/10/03)
A small parallel library of 1,4,5-trisubstituted pyrazoles was prepared in solution using a three-step procedure starting from Meldrum acid. The Meldrum acid was acylated with different acyl chlorides and the products opened with different alcohols and amines to give substituted β-keto esters and β-keto amines. Further reaction with N,N-dimethylformamide dimethylacetal and the final cyclisation were effectively carried out under microwave irradiation. Scavenger resins were employed exclusively in the first step, whereas use of microwaves allowed complete conversion of the starting materials in the other two steps. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Intramolecular N-H, O-H, and S-H Insertion Reactions. Synthesis of Heterocycles from α-Diazo β-Keto Esters
Moyer, Mikel P.,Feldman, Paul L.,Rapoport, Henry
, p. 5223 - 5230 (2007/10/02)
Several aspects of the Rh2(OAc)4-catalyzed intramolecular N-H, O-H, and S-H insertion reactions have been studied.Examination of the effect of ring size revealed that four-, five- and six-membered nitrogen heterocycles can be efficiently prepared from the corresponding α-diazo β-keto ester precursors (9a-c), whereas competing C-H insertion prevented formation of the seven-membered heterocycle.Variations in solvent, temperature, and catalyst concentration were found to play an important role in determining the product distribution in the cyclization of the 6-carbamoyl 2-diazo 3-keto ester 9c.The intramolecular X-H insertion reaction has also been successful in the synthesis of oxygen (39) and sulfur (49) heterocycles as well as a heterocycle containing two (N, O) heteroatoms (34).
