38568-76-2Relevant 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.
Generation of ethyl metathiophosphate by thermal fragmentation of O-ethyl N-substituted phosphoramidothioates
Quin, Louis D.,Hermann, Petr,Jankowski, Stefan
, p. 3944 - 3950 (2007/10/03)
O-Ethyl N-1-adamantylphosphoramidothioate was synthesized and found to fragment on heating in inert solvents to form the pyrophosphate AdNHP(S)(OEt)OP(S)(OEt)OH. The proposed mechanism involves an elimination of the amine portion with release of ethyl metathiophosphate (EtOP(S)O), as was confirmed in previous work for the comparable structure with oxygen. This transient compound then phosphorylates the starting phosphoramidothioate. O-Ethyl N,N-diethylphosphoramidothioate was also synthesized, and while it gave a similar pyro compound on heating, the reaction mixture was more complex. Both phosphoramidothioates, however, served effectively as thiophosphorylating agents toward alcohols, a silanol, and the silanol groups on the surface of silica gel. Exploratory experiments showed that these phosphoramidothioates also could thiophosphorylate the OH group of a monoester of phosphoric acid, as well as that of phosphinic acids, forming anhydrides with the partial structure.
SYNTHESIS, NMR AND STRUCTURE OF OLIGONUCLEOTIDE PHOSPHORODITHIOATES
Piotto, Martial E.,Granger, Jill Nelson,Cho, Yesun,Farschtschi, Nasser,Gorenstein, David G.
, p. 2449 - 2461 (2007/10/02)
Thiophosphoramidite as well as thiophosphoramidate chemistry has been used to prepare dithiophosphate analogues of oligonucleotides.The 1H and 31P resonances of the 3'-thymidine phosphorodithioate decamer d(CGCTpS2-TpS2-AAGCG) were assigned by two-dimensi
