The enantioselective Tsuji allylation

The first catalytic enantioselective examples of the Tsuji allylation using enol carbonates and enol silanes are described. The products possess a quaternary stereogenic center and are useful building blocks for synthetic chemistry.     

Catalytic enantioselective Nozaki-Hiyama allylation reaction with tethered bis(8-quinolinolato) (TBOx) chromium complex

The utility of the new class of chiral ligand, tethered bis(8-quinolinol) (TBOxH), is further explored. Its chromium complex, TBOxCr(III)Cl, effectively catalyzes the Nozaki-Hiyama allylation reactions of various aldehydes at room temperature with high yield (up to 95%) and high enantioselectivity (up to 99% ee). The scope of the present method is shown to be wide, and this method represents an efficient access to chiral homoallylic alcohols.     

New sulfur-coordinating chiral ligands for the Tsuji—Trost reaction

The use of sulfur-coordinating chiral ligands in the palladium-catalyzed asymmetric Tsuji—Trost reaction is reviewed.     

Synthesis of non-symmetric bis(oxazoline)-containing ligands and their application in the catalytic enantioselective Nozaki-Hiyama-Kishi allylation of benzaldehyde

We report the good to high-yielding three-step synthesis of non-symmetrical bis(oxazoline)-containing ligands possessing an N-thienylaniline unit. The convergent synthesis employed a palladium-catalysed aryl amination of 2-(2'-bromothiophene)nitrile as the key step, with sixteen ligands prepared in total. These ligands were subsequently applied in the chromium-catalysed enantioselective Nozaki-Hiyama-Kishi allylation of benzaldehyde with an optimal enantioselectivity of 73%.     

An enantioselective indium-mediated allylation reaction of aldehydes and ketones in dichloromethane

An enantioselective indium-mediated addition reaction of allylic bromides to carbonyl compounds was achieved in dichloromethane in the presence of (−)-cinchonidine. The desired products were obtained in moderate to excellent yields and with up to 75% enantioselectivity.     

Chiral diphenylthiophosphoramides: a new class of chiral ligands for the silver(I)-promoted enantioselective allylation of aldehydes

Chiral C₂-symmetric diphenylthiophosphoramides 1 and 2 were prepared in high yields from the reaction of diphenylthiophosphinic chloride with (1R,2R)-(−)-1,2-diaminocyclohexane and (1R,2R)-(+)-1,2-diphenylethylenediamine, respectively. Another novel chiral ligand 4 was prepared from reaction of diphenylthiophosphinic chloride with (R)-(+)-1,1′-binaphthyl-2,2′-diamine using butyllithium as a base. They were used as catalytic chiral ligands in the silver(I)-promoted enantioselective allylation reaction of aldehydes with allyltributyltin.     

First enantioselective total synthesis of (+)-(R)-Pinnatolide using an asymmetric domino allylation reaction

An efficient total synthesis of (+)-(R)-Pinnatolide is described. As a key step an asymmetric multicomponent domino allylation reaction of methyl levulinate is used to form the quaternary stereogenic center in a highly selective way.     

Modular iminopyridine ligands. Application to the enantioselective copper(II)-catalyzed Henry reaction

Chiral iminopyridines prepared in a modular fashion from monoterpenic (camphor-derived) ketones and pyridinylalkylamines catalyze the enantioselective Henry (nitro aldol) reaction between nitromethane and o-anisol in the presence of copper(II) acetate, with high yields and good ee (up to 86%) under straightforward experimental conditions without the need for air or moisture exclusion.     

Scandium(III)-catalyzed enantioselective allylation of isatins using allylsilanes

The scandium(III)-catalyzed enantioselective Hosomi-Sakurai allylation of isatins with various substituted allylic silanes is described. A catalyst loading as low as 0.05 mol % is utilized at room temperature to afford the 3-allyl-3-hydroxy-2-oxindoles in excellent yields and enantioselectivity up to 99% ee, including a demonstration of a gram-scale reaction. The effects of additives and varying silyl groups were explored to demonstrate the scope and application.     

New (S)-proline derivatives as catalysts for the enantioselective aldol reaction

(2S)-N- 2-[(R)-Hydroxy(phenyl)methyl]phenylpyrrolidine-2-carboxamide, (2 S)-N-{2-[(S)-hydroxy(phenyl)methyl]phenyl}pyrrolidine-2-carboxamide, and (S)-N-{2-[hydroxy-(diphenyl)methyl]phenyl}pyrrolidine-2-carboxamide were obtained and tested as catalysts for an asymmetric aldol reaction of 4-nitrobenzaldehyde with acetone.     

Chiral sulfoxides in the enantioselective allylation of aldehydes with allyltrichlorosilane

The use of chiral sulfoxides as Lewis base catalysts in the allylation of aldehydes with allyltrichlorosilane is reported.     

Proline-based P, N ligands in asymmetric allylation and the Heck reaction.

A series of phosphine-oxazoline ligands based on proline are reported. These ligands are synthesized from commercially available trans-4-hydroxy-L-proline in four steps. The ability of this type of ligand to catalyze allylic alkylation in an asymmetric fashion as well as the asymmetric Heck reaction is reported. The best of these ligands gave a palladium complex, which catalyzed the addition of dimethylmalonate to cyclopentenyl acetate in excellent yield and up to 96% ee. This same system catalyzed the Heck reaction between dihydrofuran and cyclohexene in up to 86% ee. These ligands appear to differ from the traditional phosphine-oxazoline ligands in that the stereochemistry of the stereogenic carbon next to the oxazoline is not necessarily the dominant chiral center in the induction of selectivity.     

Bisdiamidophosphite with a bisoxazoline moiety in palladium-catalyzed enantioselective allylation

Russian Chemical Bulletin - A bisdiamidophosphite ligand with stereogenic phosphorus atoms as a part of 1,3,2-diaza-phospholidine rings and a bisoxazoline backbone was synthesized and studied in...     

Diastereomeric P,N-bidentate amidophosphites based on (S,S)- and (R,R)-hydrobenzoin as ligands in the Pd-catalyzed asymmetric allylation

New P,N-bidentate diastereomeric amidophosphite ligands were obtained by phosphorylation of (S)-2-[(phenylamino)methyl]pyrrolidine involving (4S,5S)- and (4R,5R)-2-chloro-4,5-diphenyl-1,3,2-dioxaphospholanes. Their efficiency in the Pd-catalyzed enantioselective allylic substitution was compared, it was found that the reaction involving (E)-1,3-diphenylallyl acetate and pyrrolidine gives up to 75% ee.     

The synthesis of chiral tridentate ligands from l-proline and their application in the copper(II)-catalyzed enantioselective Henry reaction

A series of chiral tridentate ligands derived from readily available enantiopure l-proline were designed and synthesized. The ligands together with Cu(OAc)₂ were successfully used in asymmetric Henry reactions. Various structurally divergent aldehydes and nitromethane were converted into versatile β-nitro alcohols in MeOH at room temperature with very good yields (up to 85%) and enantioselectivities (up to 86%).     

Highly enantioselective allylation of aldehydes catalyzed by indium(III)-PYBOX complex

A chiral indium(III)-PYBOX complex prepared from indium triflate and chiral PYBOX has been discovered to effect high enantioselectivities in the addition of allyltributyl stannane to aldehydes. The allylation of a variety of aromatic, alpha,beta-unsaturated, and aliphatic aldehydes resulted in good yields and high enantioselectivities (up to 94% ee).     

Catalytic enantioselective allylation of ketones via a chiral indium(III) complex

[reaction: see text] A chiral indium complex has been discovered to effect high enantioselectivities in the addition of allyltributylstannanes to ketones. The allylation of a variety of aromatic, alpha,beta-unsaturated and aliphatic ketones resulted in good yields and high enantioselectivities (up to 92% ee).     

Chiral 1,3,2-dioxaphospholane amidophosphite in the palladium-catalyzed enantioselective allylation

Phosphorylation of (S)-1,1,2-triphenylethane-1,2-diol furnishes cyclic P*-chiral amidophosphite, whose application as a ligand in the Pd-catalyzed allyl substitution in 1,3-diphenylallyl acetate provides the products ee up to 70%.     

The application of bis(oxazoline) ligands in the catalytic enantioselective methallylation of aldehydes

A series of symmetric and non-symmetric bis(oxazoline) ligands were applied in the Nozaki-Hiyama-Kishi methallylation of a range of aromatic and aliphatic aldehydes. A non-symmetrical ligand with tert-butyl/benzyl-substituted oxazolines provided the highest enantioselectivity of 99.5% for the methallylation of benzaldehyde.     

In(OTf)_3 catalyzed allylation reaction of imines with tetraallyltin

In the presence of catalytic amount of In(OTf)3 (10 mol%), a series of aldimines reacted with tetraallyltin in a 2:1 molar ratio to afford the corresponding homoallylic amines in good yields. The good atom efficiency was achieved under mild reaction conditions and a new protocol (allyl)4Sn/In(OTf)3 for simple imines was developed.