Search

Upon treatment with LDA or alkyllithium, enantiomers of P-chiral phosphinates, phosphinothioates, phosphinoamidates, thionophosphinates, thionophosphinothioates and thionophosphinoamidates undergo clean [1,3]- and [1,2]-rearrangements with complete stereoselectivity, with retention of configuration at phosphorus, to provide functionalised tertiary phosphine oxides and phosphine sulfides; the [1,2]-rearrangements of the phosphinoamidates are previously unrecorded. (C) 2001 Elsevier Science Ltd. All rights reserved.

Reaction of (R-P)- and (S-P)-tert-butylphenylphosphinobromidates and tert-butylphenylthionophosphinochloridates with metallated phenol and BINOL alkoxides, thioalkoxides, amides and enolates leading with clean inversion at phosphorus to phosphinates, phosphinothiolates and phosphinoamidates, and the corresponding thionophosphorus compounds are described. (C) 2001 Elsevier Science Ltd. All rights reserved.

Upon treatment with LDA or alkyllithium, enantiomers of P-chiral phosphinates, phosphinothioates, phosphinoamidates, thionophosphinates, thionophosphinothioates and thionophosphinoamidates undergo clean [1,3]- and [1,2]-rearrangements with complete stereoselectivity, with retention of configuration at phosphorus, to provide functionalised tertiary phosphine oxides and phosphine sulfides; the [1,2]-rearrangements of the phosphinoamidates are previously unrecorded. (C) 2001 Elsevier Science Ltd. All rights reserved.

Reaction of (R-P)- and (S-P)-tert-butylphenylphosphinobromidates and tert-butylphenylthionophosphinochloridates with metallated phenol and BINOL alkoxides, thioalkoxides, amides and enolates leading with clean inversion at phosphorus to phosphinates, phosphinothiolates and phosphinoamidates, and the corresponding thionophosphorus compounds are described. (C) 2001 Elsevier Science Ltd. All rights reserved.

Upon treatment with LDA or alkyllithium, enantiomers of P-chiral phosphinates, phosphinothioates, phosphinoamidates, thionophosphinates, thionophosphinothioates and thionophosphinoamidates undergo clean [1,3]- and [1,2]-rearrangements with complete stereoselectivity, with retention of configuration at phosphorus, to provide functionalised tertiary phosphine oxides and phosphine sulfides; the [1,2]-rearrangements of the phosphinoamidates are previously unrecorded. (C) 2001 Elsevier Science Ltd. All rights reserved.

Reaction of (R-P)- and (S-P)-tert-butylphenylphosphinobromidates and tert-butylphenylthionophosphinochloridates with metallated phenol and BINOL alkoxides, thioalkoxides, amides and enolates leading with clean inversion at phosphorus to phosphinates, phosphinothiolates and phosphinoamidates, and the corresponding thionophosphorus compounds are described. (C) 2001 Elsevier Science Ltd. All rights reserved.

P-Chiral tertiary phosphane oxides have been prepared from each of the secondary phosphane oxides racemic 1, (S-p)-(-)-4 and (R-p)-(+)-tert-butylphenylphosphane oxide (5) by lithiation with LDA or nBuLi, or sodiation with sodium hydride, in THF, and then by treatment with a series of primary alkyl halides. Doubly P-chiral ditertiary bis(phosphane oxides) are also obtained from these metallated secondary phosphane oxides by treatment with electrophiles based on straight-chain, tartrate-derived, and bishalomethylarene dihalides. In general, the bis-phosphane oxides are obtained in good yields. However, when the alpha,omega-dihalide bears an embedded heteroatom (O or Si), yields are diminished. The enantiomeric purity of each of the products was assessed through admixture with (R-p)- and (S-p)-tert-butyl(phenyl)phosphanylthioic acids and measurement of the tert-butyl resonances in the H-1-NMR spectra. In all cases, the act of metallation of the enantiomerically pure secondary phosphane oxide followed by its alkylation is not accompanied by detectable racemization. This method for preparing P-chiral tertiary phosphane oxides is therefore more straightforward than those described previously.

P-Chiral tertiary phosphane oxides have been prepared from each of the secondary phosphane oxides racemic 1, (S-p)-(-)-4 and (R-p)-(+)-tert-butylphenylphosphane oxide (5) by lithiation with LDA or nBuLi, or sodiation with sodium hydride, in THF, and then by treatment with a series of primary alkyl halides. Doubly P-chiral ditertiary bis(phosphane oxides) are also obtained from these metallated secondary phosphane oxides by treatment with electrophiles based on straight-chain, tartrate-derived, and bishalomethylarene dihalides. In general, the bis-phosphane oxides are obtained in good yields. However, when the alpha,omega-dihalide bears an embedded heteroatom (O or Si), yields are diminished. The enantiomeric purity of each of the products was assessed through admixture with (R-p)- and (S-p)-tert-butyl(phenyl)phosphanylthioic acids and measurement of the tert-butyl resonances in the H-1-NMR spectra. In all cases, the act of metallation of the enantiomerically pure secondary phosphane oxide followed by its alkylation is not accompanied by detectable racemization. This method for preparing P-chiral tertiary phosphane oxides is therefore more straightforward than those described previously.

P-Chiral tertiary phosphane oxides have been prepared from each of the secondary phosphane oxides racemic 1, (S-p)-(-)-4 and (R-p)-(+)-tert-butylphenylphosphane oxide (5) by lithiation with LDA or nBuLi, or sodiation with sodium hydride, in THF, and then by treatment with a series of primary alkyl halides. Doubly P-chiral ditertiary bis(phosphane oxides) are also obtained from these metallated secondary phosphane oxides by treatment with electrophiles based on straight-chain, tartrate-derived, and bishalomethylarene dihalides. In general, the bis-phosphane oxides are obtained in good yields. However, when the alpha,omega-dihalide bears an embedded heteroatom (O or Si), yields are diminished. The enantiomeric purity of each of the products was assessed through admixture with (R-p)- and (S-p)-tert-butyl(phenyl)phosphanylthioic acids and measurement of the tert-butyl resonances in the H-1-NMR spectra. In all cases, the act of metallation of the enantiomerically pure secondary phosphane oxide followed by its alkylation is not accompanied by detectable racemization. This method for preparing P-chiral tertiary phosphane oxides is therefore more straightforward than those described previously.