EPR studies of the additon of 1,1-bis(alkoxycarbonyl)alkyl radicals and tris(ethoxycarbonyl)methyl radicals to alkenes and to alkyl isocyanides
作者:Val�rie Diart、Brian P. Roberts
DOI:10.1039/p29920001761
日期:——
The radical H2CCH(CH2)3Ċ(CO2Et)2 undergoes rapid 5-exo-cyclisation with a lower activation energy than that for corresponding cyclisation of the unsubstituted hex-5-enyl radical; this is attributed to the electrophilic nature of the radical centre in the former species. Addition of α-alkoxycarbonyl(alkyl) radicals to alkyl isocyanides occurs at the terminal carbon atom to give imidoyl radicals which
Absolute rate constants for some reactions of the triethylamine-boryl radical and the borane radical anion
作者:Brad Sheeller、Keith U. Ingold
DOI:10.1039/b009494n
日期:——
generated the title radicals which were found to have broad, featureless absorptions in the visible region. Rate constants for H-atom abstraction from Et3N→BH3 by cumyloxyl radicals show a small solvent dependence, e.g. 12 × 107 and 2.2 × 107 dm3 mol−1 s−1 in isooctane and acetonitrile, respectively. Rate constants for halogen atom abstraction by Et3N→BH2˙ and BH3˙− from a number of chlorides and bromides
Stereospecific displacement of sulfur from chiral centers. activation via thiaphosphonium salts.
作者:Grant A. Krafft、Thomas L. Siddall
DOI:10.1016/s0040-4039(00)94972-4
日期:1985.1
The first general method for direct displacement of sulfur from chiral carbon centers has been developed. Chiral mercaptans are readily converted to the corresponding thiaphosphonium salts by treatment with t-butyl hypochlorite and hexamethylphosphorous triamide. Metathesis with ammonium hexafluorophosphate provides stable, isolable, crystalline salts which undergo clean nucleophilic diplacement with