Asymmetric Addition of Diethylzinc to Aldehydes Catalyzed by Chiral γ_Amino Alcohols

New chiral gamino alcohols 1-4 were synthesized and applied in the asymmetric addition of diethylzinc to aldehydes to give sec-alcohol with up to 94.0% enantiomeric excess.

Novel Chiral Ferrocenyl Aziridino Alcohol Catalysts Promoting Asymmetric Addition of Diethylzinc to Aldehydes

Optically active aziridino alcohols containing ferrocenyl groups were prepared from commercially available L-threonine in excellent yields and used as catalysts to promote the asymmetric addition of diethylzinc to aryalde-hydes to afford 1-arylpropanol in up to 84% enantiomeric excesses with moderate to good yields.

Optically Active Helical Poly[(S)-3-vinyl-2,2'-dihydroxy-1,1'-binaphthyl]:New Ligand for Asymmetric Addition of Diethylzinc to Aryl Aldehyde

Poly[(S)-3-vinyl-2,2'-dihydroxy-1,1'-binaphthyl](L*)was obtained by taking off the protecting groups of poly[(S)-3-vinyl-2,2'-bis(methoxymethoxy)-1,1'-binaphthyl](poly-1).L*was proved to keep a stable helical con-formation in solution.The application of helical L*in the asymmetric addition of diethylzinc to aldehydes has been studied.The catalytic system employing 10 mol%of L*and 150 mol%of Ti(OiPr)_(4) was found to promote the addi-tion of diethylzinc to a wide range of aromatic aldehydes,giving up to 99%enantiomeric excess(ee)and up to 93%yield of the corresponding secondary alcohol at 0℃.The chiral polymer can be easily recovered and reused with-out loss of catalytic activity as well as enantioselectivity.

Synthesis of a Newly Modified Poly-H8-BINOL Ligand and Its Applications in the Asymmetric Addition of Triethylalumininm to Aromatic Aldehydes

A new H8-BINOL polymer was synthesized by radical polymerization and proved to be an effective cata- lyst in enantioselective addition of triethylaluminium to aromatic aldehydes in the presence of titanium isopropoxide. The polymer can be prepared with simple steps and reused without losing its enantioselectivity and catalytic activity.

Synthesis of new chiral 1,2,3,4-tertrahydroisoquinoline β-amino alcohol for asymmetric diethylzinc addition to aryl aldehydes(Ⅰ)

Four new chiral 1,2,3,4-tetrahydroisoquinoline-derived G-amino alcohols were synthesized from commercially available LDOPA. These ligands were evaluated in the asymmetric addition of diethylzinc to benzaldehydes and showed different catalytic activities （up to 86% ee）. The solvent played an important role in the enantioselective process. The transition state models were proposed to explain the reversion of the product configuration.

Asymmetric Photocatalyzed Addition of Cyclic Ammes to the Chiral 5-(l)-Menthyloxy-2(5H)-furanone

The benzophenone-initiated photoaddition of N-methyl ammes 2 to the chiral synthon1 proceeds in a regiospecitlc and highlyr stereocontrolled thshion to give the C-C photoadductscontaining a ne\viy stereogenic center 3a-3c. The enantiomerically pure N-C photoadducts, aminobutenolides 5a-5c have been obtained from the enantioselective photoaddition of secondary cyclicammes 4 with the chiral synthon 1 under the same conditions.

Asymmetric Conjugate Addition of Alcohols to (R)-(-)-5-[(1R,2S,5R)-Menthyloxy]-2-(5H)-Furanone

A series of enantiomencally pure (4R,5R)-(-)-4-alkryloxy-5-[(1R,2dihydro-2(5H)-furanones (2) have been synthesized in excellent yields via asymmetric conjugateadditions of primary alcohols to (R)-(-)-5-[(1R,2S,5R)-menthyloxy]-2(5H)-furanone (1) in the presenceof a catalytic amount of sodium in DMF, which provides access to new multifunctional homochiralbuilding blocks, optically. pure (R) or (S)-2-alkyloxy- 1,4-butanediols (3).

Syntheses and Crystal Structures of Chiral BINOL Derivatives and Their Applications in Enantioselective Lewis Acid Catalyzed Addition of Diethylzinc to Aldehydes

Two novel chiral BINOL derivatives with bis（benzylamine） groups at the 3,3- positions have been synthesized through the condensation reaction between 2,2＇-bis（methoxymethyleneoxy）-1,1＇-binaphthyl-3,3＇-dicarboxylic acid and benzylamine or N-phenyl benzylamine in the presence of triethylamine. Suitable single crystal of （R）-N,N＇-dibenzyl-2,2＇-dihydroxy-1, 1＇-binaphthly-3,3＇-diformamide （R）-3 for X-ray diffraction was obtained by recrystallization at room temperature from the mixture solvents. Crystallographic data of （R）-3： C40H36N2O6, Mr = 640.71, monoclinic, space group P21, a = 6.746（3）, b = 21.883（9）, c = 11.723（5）A,β = 104.605（7）°, Z= 2, V= 1674.7（12）A^3, Dc = 1.271 g/cm^3, F（000） = 676, R = 0.0729, wR = 0.1687 andμ（MoKa） = 0.086 mm^-1. Two chiral BINOL ligands were found to be effective in the enantioselective addition of diethylzinc to aldehydes and much different enantioselectivity was observed both in the presence and absence of Ti（Oipr）4. in the former case, （R）-3 showed moderate enantioselectivity, which was lower than that of （R）-BINOL＇s; and in the latter case, （R）-4 gave the highest enantioselectivity up to 93.3% ee.

Crystal Structure of (R)-3,3′-Bis(benzyloxymethyl)-1,1′-bi-2,2′-naphthol and Its Applications in Enantioselective Lewis Acid Catalyzed Addition of Diethylzinc to Aldehydes

The title compound （R）-3,3＇-bis（benzyloxymethyl）-1,1＇-bi-2,2＇-naphthol （R）-3 has been synthesized through the deprotection of MOM group by iprOH/HCl in 83% isolated yield and the suitable single crystals for X-ray diffraction were obtained by recrystallization at room temperature from the mixture solvents. Crystallographic data for （R）-3： C36H30O4, Mr = 526.60, triclinic, space group P1, a = 10.057（6）, b = 11.934（7）, c = 12.314（6） A, α = 85.52（2）, β = 70.245（13）, γ = 76.554（11）°, Z= 2, V 1352.8（13） A^3, Dc = 1.293 g/cm^3, F（000） = 556, R = 0.0745, wR = 0.1933 and #（MoKa） = 0.083 mm^-1. The title compound （R）-3 was found to be effective in the enantioselective addition of diethylzinc to aldehydes both in the presence and absence of Ti（Oipr）4. In the latter case, （R）-3 showed much higher catalytic activity and enantioselectivity than （R）-BINOL＇s.

Synthesis of New Chiral [2-（1-Hydroxyalkyl）pyrrolidino]methylferrocenes and Application to the Catalytic Asymmetric Addition of Diethylzinc to Arylaldehydes

A series of new optically active [2-（1-hydroxyalkyl）pyrrolidino]methylferrocenes were conveniently prepared from commercially available L-proline and ferrocenecarboxylic acid. The crystal structure of key intermediate was obtained. They were then applied to catalyze enantioselective addition of diethylzinc to arylaldehydes with enantioselectivity up to 99%. The effects of the ligand structures on the enantioselectivity were also studied.

Fructose derived pyridyl alcohol ligands: synthesis and application in the asymmetric diethylzinc addition to aldehydes

Easily available chiral ketones were employed for the synthesis of optically active pyridyl alcohols, which were applied in the asymmetric diethylzinc addition to aldehydes, up to 89.4% e.e. was obtained using D-fructose-derived pyridyl alcohol.

Synthesis of the Stereoisomers of the Sex Pheromones of the Southern Corn Rootworm

A simple and efficient asymmetric synthesis of the sex pheromone of the southern corn rootworm is discribed. The key step is the asymmetric Michael addition of enoylsultam with virtually complete asymmetric induction( e.e. %>99%)

Synthesis of γ-Substituted Alcohol with Polymer-bound Amide

With solid phase organic synthesis method(SPOS), polymer-bound N-enoylprolinol(4) was prepared by the attachment of N-enoylprolinol(3) to Merrifield resin and was used for asymmetric Michael additions for the first time. The enantiomeric excess obtained by this method is increased as compared with that obtained by the corresponding solution phase reactions.

Wang Resin-supported Enantioselective Catalysts for the Asymmetric Michael Additions of Acetone to β-Nitroolefins

Two Wang resin-supported （1R,2R）-（＋）-1,2-DPEN（DPEN=diphenylethylenediamine） catalysts were synthesized from cyanuric chloride and trimesoyl chloride, respectively. These two catalysts were characterized by FTIR, TGA and elemental analysis. The results demonstrated that （1R,2R）-（＋）-1,2-DPEN was successfully bonded to the surface of Wang resin through the amido linkage. Subsequently, the asymmetric Michael addition of acetone to β-nitrostyrene was employed to evaluate their catalytic performance. It was found that the catalyst generated from trilnesoyl chloride exhibited much better catalytic behavior than our previously reported catalyst, likely attributed to the multiple hydrogen-bond interaction between β-nitrostyrene and amide group, which made the catalytic transition intermediates more stable. Under the optimal conditions, 76.1% β-nitrostyrene conversion and 93.8% enantioselectivity were obtained. Finally, the generality of this catalyst was examined with Michael additions of acetone to β-nitroolefms and excellent enantioselectivities（91.9% to 99.9%） were achieved.

Preparation of 6,6′-Bisperfluoroalkylated BINOLs and Their Application in Asymmetric Alkylation of Benzaldehyde

Bis(1H,1H,2H,2H perfluorooctyl) BINOL and 6,6′ bis(1 H ,1 H ,2 H ,2 H perfluorodecyl) BINOL were synthesized through Suzuki coupling reaction and used in fluorous biphase asymmetric alkylation of benzaldehyde. Good enantioselectivity was obtained and the catalysts could be recovered by liquid liquid extraction.

Design and synthesis of some new C_2-symmetric chiral disulfonamides from aminoacids and the application in diethyl zinc addition to benzaldehyde

Nine C2-symmetric chiral disulfonamldes were designed and synthesized from L-valine, L-phenylalanine and L-leucine respectively via one-pot ring opening of aziridines. The application of these disulfonamides as catalyst in the addition of diethyl zinc to benzaldehyde in three reagent systems: Ligand-Ti(OiPr)4-Et2Zn; Ligand-Ti(OiPr)4-H2O-Et2Zn; Ligand-Et2Zn was also described.

Concise synthesis of valuable chiral N-Boc-β-benzyl-β-amino acid via construction of chiral N-Boc-3-benzyl-5-oxoisoxazolidine through cross-metathesis/conjugate addition/oxidation

Valuable chiral N-Boc-β-benzyl-β-amino acid was concisely synthesized via construction of chiral NBoc-3-benzyl-5-oxoisoxazolidine through cross-metathesis/conjugate addition/oxidation.All of the starting materials for the synthesis of chiral N-Boc-β-benzyl-β-amino acid are cheap,and two-step short procedure make it easy for the rapid construction of various chiral β-arylmethyl-β-amino acids and important drugs,such as sitagliptin phosphate.

Enantioselective Conjugate Addition of Diethylzinc to Chalcone Catalyzed by Ni(acac)_2 and Chiral β-Amino Alcohols

Enantioselective conjugate addition of diethylzinc to chalcone was carried out in the presence of Ni(acac) 2 complexed with five pyrrolidinylmethanols derived from L proline. ( S ) N Benzyl 2 (1 hydroxy 1 methylethyl) pyrrolidine was found to be the best ligand in asymmetric conjugate addition among the five ligands. The products were obtained with up to 70% ee . The configuration of the product was determined jointly by the substituents on the carbon of the hydroxy group and the nitrogen atom.

Chiral Cinchona Alkaloid-Thiourea Catalyzed Mannich Reaction for Enantioselective Synthesis of β-Amino Ketones Bearing Benzothiazol Moiety

Mannich reactions of imine with acetylacetone were effectively catalyzed by the modified chiral cinchona alka-loid-derived thiourea. The reactions led to chiral r-amino carbonyl compounds in high yields and good enantiose-lectivities. The study demonstrated for the first time that Mannich reactions of unmodified acetylacetone with het-erocyclic imine derived from benzothiazole can be promoted by chiral bifunctional organocatalyst.