Dissociation of Carbanions from Acyl Iridium Compounds: An Experimental and Computational Investigation
作者:Joseph G. Cordaro、Robert G. Bergman
DOI:10.1021/ja045859l
日期:2004.12.1
of CF(3)(-) to act as a leaving group came from the investigation of the analogous methyl and chloride derivatives Cp(PMe(3))Ir(Me)[C(O)CF(3)] and Cp(PMe(3))Ir(Cl)[C(O)CF(3)]. Both of these compounds undergo a similar loss of trifluoromethyl anion, generating an iridium carbonyl cation and CF(3)D in CD(3)OD. Three additional acyl hydrides, Cp(PMe(3))Ir(H)[C(O)R(F)] (where R(F) = CF(2)CF(3), CF(2)CF(2)CF(3)
Several multifunctional derivatives of methylthiomalonic acid (= 2-(thiocarboxy)acetic acid), i.e. 20a,b, 21, 22a,b, and 24, were prepared from thiols bearing a functionalized head group, i.e. from 9a,b, 12, and 16d,f (Schemes 4 and 5). The association constants of the two dithio podands 8b and 11 with K+ were determined.
Kinetic and molecular orbital analyses of dicarboxylic acylcarnitine methylesterification show that derivatization may affect the screening of newborns by tandem mass spectrometry
Newborns are routinely screened for organic acidemias by acylcarnitine analysis. We previously reported the partial catalytic methylesterification of dicarboxylic acylcarnitines by benzenesulfonic acid moiety in the solid extraction cartridge during extraction from serum. Since the diagnosis of organic acidemias by tandem mass spectrometry is affected by the higher molecular weight of these derivatized acylcarnitines, we investigated the methylesterification conditions. The kinetic constants for the methylesterification of carboxyl groups on the acyl and carnitine sides of carnitine were 2.5 and 0.24 h (1), respectively. The physical basis underlying this difference in methylesterification rates was clarified theoretically, illustrating that methylesterification during extraction proceeds easily and must be prevented. (C) 2015 Elsevier Ltd. All rights reserved.
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Five- and six-membered lactones and lactams by tandem dealkoxycarbonylation-Michael addition reactions