- Preparative and mechanistic studies toward the rational development of catalytic, enantioselective selenoetherification reactions
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A systematic investigation into the Lewis base catalyzed, asymmetric, intramolecular selenoetherification of olefins is described. A critical challenge for the development of this process was the identification and suppression of racemization pathways available to arylseleniranium ion intermediates. This report details a thorough study of the influences of the steric and electronic modulation of the arylselenenyl group on the configurational stability of enantioenriched seleniranium ions. These studies show that the 2-nitrophenyl group attached to the selenium atom significantly attenuates the racemization of seleniranium ions. A variety of achiral Lewis bases catalyze the intramolecular selenoetherification of alkenes using N-(2-nitrophenylselenenyl)succinimide as the electrophile along with a Bronsted acid. Preliminary mechanistic studies suggest the intermediacy of ionic Lewis base-selenium(II) adducts. Most importantly, a broad survey of chiral Lewis bases revealed that 1,1′-binaphthalene-2,2′-diamine (BINAM)-derived thiophosphoramides catalyze the cyclization of unsaturated alcohols in the presence of N-(2-nitrophenylselenenyl)succinimide and methanesulfonic acid. A variety of cyclic seleno ethers were produced in good chemical yields and in moderate to good enantioselectivities, which constitutes the first catalytic, enantioselective selenofunctionalization of unactivated olefins.
- Denmark, Scott E.,Kalyani, Dipannita,Collins, William R.
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supporting information; experimental part
p. 15752 - 15765
(2011/02/22)
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- NEW CHEMISTRY AND STEREOCHEMISTRY OF ORGANOPHOSPHORUS PSEUDOHALOGENS
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Synthesis, chemistry and stereochemistry of organophosphorus-sulfur(selenium)pseudohalogens are discussed and rationalized.
- Michalski, Jan,Skowronska, Aleksandra,Lopusinski, Andrzej
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- REACTIONS OF SULFUR DIOXIDE WITH AMINOPHOSPHINES
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The reactions of SO2 with tris-dimethylaminophosphine, bis-dimethylaminofluorophosphine, bis-dimethylaminochlorophosphine, dimethylaminodifluorophosphine, dimethylaminodichlorophosphine, 1,3-dimethyl-2-fluoro-1,3,2-diazaphospholidine and 1,3-dimethyl-2-chloro-1,3,2-diazaphospholidine have been investigated.The complex reactions are dominated by facile oxidation of the respective phosphine to phosphoryl and thiphosphoryl derivatives.The new heterocyclic phosphines CH3(O)F and CH3(S)F have been isolated and characterized by NMR, infrared, and mass spectrometry.
- Light, R. W.,Paine, R. T.
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p. 255 - 258
(2007/10/02)
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- Desulfurization of Organic Trisulfides by Tris(dialkylamino)phosphines. Mechanistic Aspects
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Tris(dialkylamino)phosphines effect a rapid desulfurization of trisulfides to disulfides under mild conditions.The reaction mechanism involves a bimolecular process, proceeding by the rate-determining formation of a phosphonium salt intermediate.The central sulfur atom of a diaryl trisulfide is removed in the process, while a dialkyl trisulfide loses a terminal sulfur atom to the aminophosphine.
- Harpp, David N.,Ash, David K.,Smith, Roger A.
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p. 5155 - 5160
(2007/10/02)
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