作者:V. V. Popic、S. M. Korneev、V. A. Nikolaev、I. K. Korobitsyna
DOI:10.1055/s-1991-26416
日期:——
The sodium hydride/dibenzo-18-crown-6 ether system was found to be an effective base for the synthesis of 1,3-diketones by the Claisen condensation. The use of potassium fluoride (with or without crown ether) as the base in diazo-transfer reactions extends this reaction to the synthesis of hindered diazo diketones. In the case of isomeric 1,3-diketones, the stereoselectivity of the process considerably rises.
relative kinetic and thermodynamic stereoselectivities shown in the reaction between methyl iodide and either N-methylpiperidines or thians is explained by different directions of approach to these 6-memberedrings during axial attack.