Alkylations of Chiral, Phosphoryl- and Thiophosphoryl-Stabilized Carbanions
摘要:
A general method for the preparation of enantiomerically enriched phosphonic acids and phosphonates with three different a-substitution patterns (aryl, alkyl, and alkoxy) has been developed. Anions derived from enantiomerically enriched thiophosphonamidates (2-thioxo-1,3,2-oxazaphosphorinanes) underwent smooth electrophilic substitutions with excellent diastereoselectivity for both cis and trans stereoisomers. Highly enantioselective synthesis of alpha-alkoxyphosphonates in either antipodal form can be achieved by the employment of highly diastereoselective alkylation with anions derived from the corresponding P-methoxymethyl analogs in the presence of HMPA or PMDTA. Implications for the aggregation states and reactive conformations of the anions are discussed.
The asymmetric synthesis of α-substituted α-methyl and α-phenyl phosphonic acids: Design, carbanion geometry, reactivity and preparative aspects of chiral alkyl bicyclic phosphonamides
作者:Youssef L. Bennani、Stephen Hanessian
DOI:10.1016/0040-4020(96)00829-0
日期:1996.10
The design, preparation, structural and spectroscopic analyses of topologically unique and enantiomerically pure alkylphosphonamides are described. In the case of α-ethyl and α-benzyl phosphonamides, the geometry of both the secondary and tertiary carbanions was determined to be planar through deprotonation/deuteration/alkylation experiments. Stereoselective alkylations of such systems proceeded in
Diastereoselective alkylations of chiral, phosphorus-stabilized carbanions: <i>N</i>-alkyl substituent effects in <i>P</i>-alkyl-1,3,2-diazaphosphorinane 2-oxides
作者:Scott E Denmark、Jung-Ho Kim
DOI:10.1139/v99-251
日期:2000.6.1
A systematic study of the diastereoselective alkylation of anionsderivedfrom racemic N-substituted P-alkyl 1,3,2-diazaphosphorinane 2-oxides was carried out with variation of the N-substituent. High diastereoselectivity for the methylation of a P-benzyl anion has been achieved with N-neopentyl derivative 5d. Similarly, a P-ethyl anionderivedfrom N-neopentyl derivative 6d showed high diastereoselectivity
Rh(I)-Catalyzed Enantioselective Hydrogenation of α-Substituted Ethenylphosphonic Acids
作者:Kaiwu Dong、Zheng Wang、Kuiling Ding
DOI:10.1021/ja305780z
日期:2012.8.1
A class of chiral Rh(I) catalysts containing monodentate phosphorous aciddiesters tautomerized from the corresponding secondary phosphine oxides was discovered by serendipitous hydrolysis of phosphoramidite ligands. The evolved catalysts demonstrated unprecedented enantioselectivities (98-99% ee) and high catalytic activities (as low as 0.01 mol% catalyst loading) in asymmetric hydrogenations of a
A practical synthetic approach to chiral α-aryl substituted ethylphosphonates
作者:Natalia S Goulioukina、Tat'yana M Dolgina、Irina P Beletskaya、Jean-Christophe Henry、Damien Lavergne、Virginie Ratovelomanana-Vidal、Jean-Pierre Genet
DOI:10.1016/s0957-4166(01)00031-3
日期:2001.2
A convenientgeneral method is reported for the synthesis of α-aryl substituted ethylphosphonic acids and esters by hydrogenation of α-aryl substituted ethenylphosphonic acids and esters. Racemic α-arylethylphosphonic acids and esters were prepared in 70–88% yield under palladium-assisted transferhydrogenation conditions using ammonium formate. Asymmetric hydrogenation of α-arylethenylphosphonic acids
The first asymmetrichydrogenation of vinylphosphonic acids and esters to the corresponding arylethylphosphonic acids and esters using chiralRu(II) catalysts is reported with enantiomeric excesses up to 86%.