Ring-Opening of 4-Isoxazolines: Competitive Formation of Enamino Derivatives and a,b-Enones
摘要:
Ring-opening of 3-substituted 4-isoxazolines, proceeding through the intermediate isoxazolinium salts, follows two competing reaction pathways leading to alpha,beta-enones and enamines respectively. The rearrangement courses can be controlled as a function of substitution pattern and experimental conditions.
Enzyme Promiscuity as a Remedy for the Common Problems with Knoevenagel Condensation
作者:Dominik Koszelewski、Ryszard Ostaszewski
DOI:10.1002/chem.201901491
日期:2019.8
lipase‐catalyzed tandemreaction toward α,β‐enones/enoesters is presented. For the synthesis of the desired products the tandem process based on enzyme‐catalyzed hydrolysis and Knoevenagel reaction starting from enol acetates and aldehyde is developed. The relevant impact of the reaction conditions including organic solvent, enzyme type, and temperature on the course of the reaction was revealed. It
Synthesis of ethyl 2-aminodihydro-5-pyrimidinecar-boxylate derivatives and 3,7-diethoxycarbonyl-4,6-dihydro-2,4,6,8-tetraaryl-1<i>H</i>-pyrimido[1,2-<i>a</i>]pyrimidines
Reactions of ethyl 3-aryl-2-benzoylpropenoates 1 with guanidine and N-alkyl(or benzyl)guanidines have been investigated. Ethyl 2-aminodihydro-5-pyrimidinecarboxylate derivatives 3, 4 or 5, and 3,7-diethoxy-carbonyl-4,6-dihydro-2,4,6,8-tetraaryl-1H-pyrimido[1,2-a]pyrimidines 6 have been synthesized.