4743-38-8Relevant academic research and scientific papers
New hydrogen-bonding organocatalysts: Chiral cyclophosphazanes and phosphorus amides as catalysts for asymmetric Michael additions
Klare, Helge,Neudoerfl, Joerg M.,Goldfuss, Bernd
, p. 224 - 236 (2014/02/14)
Ten novel hydrogen-bonding catalysts based on open-chain PV-amides of BINOL and chinchona alkaloids as well as three catalysts based on rigid cis-PV-cyclodiphosphazane amides of N1,N1-dimethylcyclohexane-1,2-diamine have been developed. Employed in the asymmetric Michael addition of 2-hydroxynaphthoquinone to β-nitrostyrene, the open-chain 9-epi-aminochinchona-based phosphorus amides show a high catalytic activity with almost quantitative yields of up to 98% and enantiomeric excesses of up to 51%. The cyclodiphosphazane catalysts show the same high activity and give improved enantiomeric excesses of up to 75%, thus representing the first successful application of a cyclodiphosphazane in enantioselective organocatalysis. DFT computations reveal high hydrogen-bonding strengths of cyclodiphosphazane PV-amides compared to urea-based catalysts. Experimental results and computations on the enantiodetermining step with cis-cyclodiphosphazane 14a suggest a strong bidentate H-bond activation of the nitrostyrene substrate by the catalyst.
THIONO COMPOUNDS. 8. MUTAGENIC ACTIVITY OF REPRESENTATIVE AMIDES OF THIOPHOSPHORIC ACID
Mitchell, William M.,Breau, Alan P.,Swinson, Joel,Field, Lamar
, p. 151 - 158 (2007/10/02)
Amides of thiophosphoric acid were studied, in order to initiate correlations of mutagenicity with structure, by use of a modified Ames assay.Representative thiophosphoramides of the structure (XArNH)3PS were not mutagenic, irrespective of whether X was a reference hydrogen atom, an electron-withdrawing, or an electron-donating group.One phosphoramidothioate of the structure (2,4-X2ArNH)P(S)(OCH2CH3)2 effected base-pair mutation when X was F (but not when X was CH3), when S-9 liver homogenate with exogenous NADP was used; when X was H, only inconsistent mutagenic activity following metabolic activation was observed even at concentrations near those that produced acute cellular toxicity.Mutagenicity of these N-arylamides thus appears to follow guidelines concluded for esters, (RO)3PS, i.e. that mutagenesis is most probable when two groups are small enough to permit nucleophilic attack by a biomacromolecule on the electrophilic phosphorus atom.That the third group should be electron withdrawing again seems important although it need not be a good leaving group.An alkyl thionamide, 3PS, resembled the oxygen counterpart, 3PO, to which it probably is biotransformed, in being only marginally mutagenic.We conclude that the hazard of mutagenesis is likely to be less with amides than with esters of thiophosphoric acid and that most of the representative thioamides tested are unlikely to pose serious mutagenic hazards. - Key Words: Ames assay, base-pair mutation, mutagenesis, phosphoramidothioate, thionamide, thiophosphoramide
