Rate Constants for 5- and 6-Exo Secondary Alkyl Radical Cyclizations onto N,N-Diphenylhydrazones
作者:Claudio F. Sturino、Alex G. Fallis
DOI:10.1021/jo00101a007
日期:1994.11
Competitive ''radical clock''-type cyclizations of hydrazones and alkenes established that the rate constants for 5-exo cyclizations onto N,N-diphenylhydrazones are 1.1 x 10(8) s(-1) and 4.6 x 10(7) s(-1) at 80 degrees C to the cis- and trans-cyclopentylhydrazines, respectively (about 200 times faster than the corresponding cyclization rate for 5-exo alkenes). The 6-exo hydrazone rate constant is 9.4 x 10(5) s(-1) at 80 degrees C for both cis and trans isomers with activation barriers of 5.6 and 6.2 kcal/mol, respectively.
Transition-Metal-Free Trifluoromethylation of Aldehyde Derivatives with Sodium Trifluoromethanesulfinate
A metal-free and cost-effective synthetic protocol for the trifluoromethylation of N,N-disubstituted hydrazones with Langlois’s reagent (CF3SO2Na) to afford the corresponding functionalized trifluoromethyl ketone hydrazones has been established. It is proposed that a radical/SET mechanism proceeding via a trifluoroalkyl radical may be involved in the reaction. Applications of the methodology in industry
已经建立了一种无金属且具有成本效益的合成方案,用于使用Langlois试剂(CF 3 SO 2 Na)对N,N-二取代进行三氟甲基化,以提供相应的官能化三氟甲基酮。建议通过三氟烷基自由基进行的自由基/ SET机理可能参与该反应。我们将发现该方法在工业中的应用,并将继续在我们的实验室中开发使用Langlois试剂进行三氟甲基化的新方法。
Radical cyclisations of imines and hydrazones
作者:W. Russell Bowman、Peter T. Stephenson、Nicholas K. Terrett、Adrian R. Young
DOI:10.1016/0040-4020(95)00412-2
日期:1995.7
Radical cyclisation of sp3 carbon-centred radicals onto imines and hydrazones provides a new method for the synthesis of 5- and 6-membered ring nitrogen heterocycles. Cyclisation onto the electrophilic carbon of the C=N group and 5-exo stereoelectronic selectivity are the dominating mechanistic parameters. The C-centred radical intermediates were generated from benzeneselenyl precursors using Bu3SnH