Takehiro Yamagishi

Enantioselective hydrophosphonylation of aromatic aldehydes catalyzed by chiral titanium alkoxides

Abstract The enantioselective hydrophosphonylation of aromatic aldehydes with silylphosphite (1) or diethyl phosphonate (5a) assisted by chiral titanium alkoxides as catalyst is examined. Titanium alkoxide (7), derived from L -tratrate and Ti(O-iPr)4, was found to be an effective catalyst and induce modest enantioselectivity in the reaction.

Enantioselectivity for hydrophosphonylation of aromatic aldehydes catalyzed by lanthanum binaphthol complex. Remarkable electronic effect of aromatic substituents

Abstract Hydrophosphonylation of aromatic aldehydes with diethyl phosphite in the presence of catalytic amount of La-BINOL complex ( 2 ) proceeded enantioselectively to give the corresponding α-hydroxyphosphonates in good yield. Enantioselectivity was found to depend on the electronic nature of para -substituents.

Stereodivergent synthesis of β-amino-α-hydroxyphosphonic acid derivatives by lewis acid mediated stereosclective hydrophosphonylation of α-amino aldehydes

Abstract The highly diastereoselective synthesis of β-amino-α-hydroxyphosphonic acid derivatives was achieved by Lewis acid mediated hydrophosphonylation of α-dibenzylamino aldehyde. Diastereofacial differentiation could be controlled in either a chelation or a non-chelation manner by simple tuning of the nature of phosphoric nucleophiles.

Enantioselective synthesis of α-hydroxyphosphinic acid derivatives through hydrophosphinylation of aldehydes catalyzed by Al-Li-BINOL complex

Abstract The first catalytic asymmetric synthesis of (S)-α-hydroxy-H-phosphinates and (S,S)-α,α′-dihydroxyphosphinates were achieved by the reaction of methyl phosphinate with aldehydes in the presence of Al-Li-BINOL complex.

Stereocontrolled synthesis of hydroxymethylene phosphonate analogues of phosphorylated tyrosine and their conversion to monofluoromethylene phosphonate analogues

Abstract A stereocontrolled synthesis of protected variants 13 and 15 of HPmp 2 , a mimic of phosphorylated tyrosine, was achieved through either chiral-auxiliary assisted or chiral heterobimetal catalyzed stereoselective hydrophosphonylation of 4-formyl- l -phenylalanine derivative 7 . Fluorination of HPmp derivatives 13 and 15 thus obtained was carried out to give FPmp derivatives 16 and 17 .

Enantioselective synthesis of threo-α,β-dihydroxyphosphonates by asymmetric dihydroxylation of 1(E)-alkenylphosphonates with AD-mix reagents

Abstract Asymmetric dihydroxylation (AD) of 1(E)-alkenylphosphonates with an AD-mix-α or -β reagent was examined to give a series of optically active threo-α,β-dihydroxyphosphonates. Good enantioselectivity (>88% ee) was observed in the AD reaction of 1(E)-alkenylphosphonates with conjugated aromatic substituents. The steric effects of the ester functionality in the course of the dihydroxylation were also evaluated. Enantioselectivity and yield were significantly improved when the AD reaction was carried out with dimethyl phosphonate instead of diethyl phosphonate.

Enantioselective synthesis of threo-α,β-dihydroxyphosphonates by asymmetric dihydroxylation of vinylphosphonates. An application to the stereocontrolled synthesis of (4S,5S)-4-diethylphosphono-5-hydroxymethyl-2,2-dimethyl-1,3-dioxolane

Abstract The asymmetric dihydroxylation (AD) reaction of vinylphosphonates with AD-mix-α and -β reagents was successfully applied to the enantioselective synthesis of threo - α , β-dihydroxyphosphonates. β-Aryl substituents on the vinyl phosphonates were found to be good directors for the reaction with respect to the yield and enantioselectivity. The utility of chiral α, β-dihydroxyphosphonate 2c was illustrated by the stereocontrolled synthesis of (4 S ,5 S )-4-diethylphosphono-2,2-dimethyl-5-hydroxymethyl-1,3-dioxolane 6 , a potentially useful chiron for asymmetric synthesis of α-heteroatom-substituted phosphonates.

Diastereoselective synthesis of β-substituted α-hydroxyphosphinates through hydrophosphinylation of α-heteroatom-substituted aldehydes

The diastereoselective synthesis of β-substituted α-hydroxyphosphinates was achieved by hydrophosphinylation of α-oxy aldehydes and α-amino aldehydes with ethyl allylphosphinate catalyzed by lithium phenoxide.

Asymmetric dihydroxylation of 1-acyloxy-2(E)-alkenylphosphonates with AD-mix reagents. Effects of 1-acyloxy functional groups on the asymmetric dihydroxylation

Abstract Asymmetric dihydroxylation (AD) of a racemic mixture of 1-acyloxy-2(E)-alkenylphosphonates with AD-mix-α or -β reagents was examined. The kinetic rate of dihydroxylation was highly dependent upon the configuration of the 1-acyloxy functional group as well as the nature of substituents at the 3-position. The reaction of a racemic mixture of diethyl (E)-3-phenyl-1-acetyloxy-2-propenylphosphonate with an AD-mix-β reagent preferentially dihydroxylated the R-enantiomer to leave an unreacted S-enantiomer of high enantiomeric purity. Double diastereoselection of the resolved diethyl 3-phenyl-1-acetyloxy-2(E)-propenylphosphonate in dihydroxylation was also examined.

Diastereoselective synthesis of chiral β-amino-α-hydroxy-H-phosphinates through hydrophosphinylation of α-amino aldehydes

Abstract A stereodivergent synthesis of β-amino-α-hydroxy- H -phosphinates was achieved by ALB-catalyzed hydrophosphinylation of N , N -dibenzyl-α-amino aldehydes tuning the chirality of the catalyst.