An Enantioselective, Intermolecular α-Arylation of Ester Enolates To Form Tertiary Stereocenters

In transition-metal catalyzed, asymmetric α-arylation of carbonyl compounds, formation of tertiary centers with high enantioselectivity is a longstanding problem, due to easy enolization of the monoarylation products. Herein, we report such examples using a palladium catalyst supported by a new, (R)-H8-BINOL-derived monophosphine. Silyl ketene acetals, together with a weakly basic activator, were used as equivalents of ester anions, and they reacted smoothly with aryl triflates in excellent enantiomeric excess (ee). The usefulness of the reaction was demonstrated in a gram-scale synthesis of (S)-Naproxen in 92% ee

Syntheses of Novel Chiral Sulfinamido Ligands and Their Applications in Diethylzinc Additions to Aldehydes^†

A novel class of sulfinamido alcohol ligands 1−6 was synthesized from (S)-tert-butanesulfinamide. These ligands showed excellent catalytic activities and enantiomeric selectivities in asymmetric additions of diethylzinc to aromatic aldehydes

Syntheses of Novel Chiral Sulfinamido Ligands and Their Applications in Diethylzinc Additions to Aldehydes^†

A novel class of sulfinamido alcohol ligands 1−6 was synthesized from (S)-tert-butanesulfinamide. These ligands showed excellent catalytic activities and enantiomeric selectivities in asymmetric additions of diethylzinc to aromatic aldehydes

An Enantioselective, Intermolecular α-Arylation of Ester Enolates To Form Tertiary Stereocenters

In transition-metal catalyzed, asymmetric α-arylation of carbonyl compounds, formation of tertiary centers with high enantioselectivity is a longstanding problem, due to easy enolization of the monoarylation products. Herein, we report such examples using a palladium catalyst supported by a new, (R)-H8-BINOL-derived monophosphine. Silyl ketene acetals, together with a weakly basic activator, were used as equivalents of ester anions, and they reacted smoothly with aryl triflates in excellent enantiomeric excess (ee). The usefulness of the reaction was demonstrated in a gram-scale synthesis of (S)-Naproxen in 92% ee

An Enantioselective, Intermolecular α-Arylation of Ester Enolates To Form Tertiary Stereocenters

In transition-metal catalyzed, asymmetric α-arylation of carbonyl compounds, formation of tertiary centers with high enantioselectivity is a longstanding problem, due to easy enolization of the monoarylation products. Herein, we report such examples using a palladium catalyst supported by a new, (R)-H8-BINOL-derived monophosphine. Silyl ketene acetals, together with a weakly basic activator, were used as equivalents of ester anions, and they reacted smoothly with aryl triflates in excellent enantiomeric excess (ee). The usefulness of the reaction was demonstrated in a gram-scale synthesis of (S)-Naproxen in 92% ee

Synthesis of Novel Enantiopure Biphenyl <i>P</i>,<i>N-</i>Ligands and Application in Palladium-Catalyzed Asymmetric Addition of Arylboronic Acids to <i>N-</i>Benzylisatin

Enantiopure tetra-ortho-substituted biphenyl phosphinoimine ligands (Ra,S)-3 and (Sa,S)-3 were synthesized via multistep reactions. The first asymmetric addition reactions of arylboronic acids to N-benzylisatin catalyzed by Pd(OAc)2 and (Ra,S)-3 were studied to provide 3-aryl-3-hydroxyoxindoles in moderate yields and enantioselectivities

Synthesis of Novel Enantiopure Biphenyl <i>P</i>,<i>N-</i>Ligands and Application in Palladium-Catalyzed Asymmetric Addition of Arylboronic Acids to <i>N-</i>Benzylisatin

Enantiopure tetra-ortho-substituted biphenyl phosphinoimine ligands (Ra,S)-3 and (Sa,S)-3 were synthesized via multistep reactions. The first asymmetric addition reactions of arylboronic acids to N-benzylisatin catalyzed by Pd(OAc)2 and (Ra,S)-3 were studied to provide 3-aryl-3-hydroxyoxindoles in moderate yields and enantioselectivities

Synthesis of Enantiopure <i>tert</i>-Butanesulfinamide from <i>tert</i>-Butanesulfinyloxazolidinone

A three-step procedure for the preparation of enantiopure tert-butanesulfinamide 6 in 51% overall yield is described starting from (1R,2S)-N-Cbz-1,2-diphenylaminoethanol. The key step is the reaction of tert-butylmagnesium chloride with N-Cbz-4,5-diphenyl-1,2,3-oxathiazolidine-2-oxide 2 to afford the optical pure tert-butylsulfinyl-4,5-diphenyl-1,3-oxazolidinone 5 via an 1,5-alkoxy anion rearrangement, which is then subject to ammonia hydrolysis with LiNH2 in liquid ammonia to give (R)-tert-butanesulfinamide 6

Selective Diethylzinc Reduction of Imines in the Presence of Ketones Catalyzed by Ni(acac)₂

A selective reduction method of an electronically deficient imine in the presence of ketone was developed by employing Et2Zn and 5 mol % of Ni(acac)2. The method was applied in the reduction of SS-tert-butanesulfinyl ketimines 1 to afford amines 2 in 23−92% yields and 73:27 to 98:2 diastereoselectivities. A plausible mechanism was proposed on the basis of an NMR study

Nickel–Thiolate Complex Catalyst Assembled in One Step in Water for Solar H₂ Production

We report the use of a simple complex assembled from Ni­(II) salt and 2-mecaptoethanol in one step in water as the efficient catalyst in a molecular hydrogen system which can be sensitized by a low-cost xanthene dye, Erythrosin B. An excellent quantum efficiency of 24.5% is attained at 460 nm. This simple system is expected to contribute toward the development of economical and environmentally benign solar hydrogen production systems