Morita–Baylis–Hillman adducts as building blocks of heterocycles: a simple approach to 4-substituted pyrazolones, and mechanism investigation via ESI–MS(/MS)
作者:Rosimeire C. Barcelos、Lucas A. Zeoly、Manoel T. Rodrigues、Bruno R. V. Ferreira、Marcos N. Eberlin、Fernando Coelho
DOI:10.1007/s00706-015-1427-6
日期:2015.9
We describe herein an efficient approach for the preparation of 4-substituted 2,3-dihydro-1H-pyrazol-3-ones starting from Morita-Baylis-Hillman adducts. These heterocycles were obtained in two or three steps as single isomers with moderate to good overall yields. One efficient and alternative methodology for the synthesis of alpha-methyl-beta-ketoesters is also reported (up to 91 % yield). Additionally, the mechanism of formation of pyrazolones was investigated employing ESI-MS/MS reaction monitoring.