A Practical Catalytic Asymmetric Addition of Alkyl Groups to Ketones.

Abstract

Enantioselective syntheses Enantioselective syntheses O 0031A Practical Catalytic Asymmetric Addition of Alkyl Groups to Ketones. -The camphor derivative shown in the scheme is an efficient ligand for asymmetric addition of alkyl groups to ketones. Tertiary alcohols are obtained with excellent enantioselectivity. -(GARCIA, C.; LAROCHELLE, L. K.; WALSH*, P. J.; J.

Catalytic asymmetric alkylation of ketones using organometallic reagents

“…2b) [24,25]. In addition, diarylzinc reagents as well as a,b-unsaturated ketones were successfully employed using this ligand.…”

The Syntheses of new Camphorsulfonylated Ligands Derived from 2‐Amino‐2′‐Hydroxy‐1,1′‐Binaphthyl and Their Enantioselectivities in the Addition of Dialkylzinc Reagents to Aldehydes

“…The data show that both the catalytic activities and enantioselectivities of (S)-NOBIN derived ligands (2,4,6,8) were generally better than those of the corresponding (R)-NOBIN derivatives (1,3,5,7), which should be attributed to the different chiral matching effects of (R)-NOBIN and (S)-NOBIN's binaphthyl skeleton with (S)camphor's isoborneol backbone. Furthermore, the single sulfonyl derivatives of (S)-NOBIN (4, 8) gave better enanotioselectivities than double sulfonyl derivatives (2,6), which indicated that NOBIN's hydroxyl group improves the performance of the ligands both on the conversion of benzaldehyde and the ee value of the addition product. Compared with ketocamphorsulfonylated NOBIN ligand 4, the corresponding hydroxycamphorsulfonylated NOBIN ligand 8 gave better enantioselectivity and offered the addition product with opposite configuration possibly because of the use of different spatial arrangement of the complex catalyst.…”

“…Since Ramón and Yus firstly reported several camphorsulfonamide ligands promoting addition of dialkylzincs to aldehydes and ketones in the presence of titanium alkoxide, many camphorsulfonamide ligands derived from various aliphatic and aromatic monoamines and diamines have been tested in the addition of dialkylzinc reagents to carbonyl groups with varying success in the presence of titanium alkoxide . Among these ligands, Walsh's HOCSAC, a bis (hydroxycamphorsulfonamide) ligand derived from ( R , R )‐1,2‐cyclohexyl diamine, has been shown to be the best one so far to give excellent results with up to 99% ee value using only 2% catalyst loading.…”

Highly Efficient Asymmetric Additions of Diethylzinc to Aldehydes Triply Activated by Chiral Phosphoramide‐Zn(II) Complexes Derived From Cinchona Alkaloids

“…[4][5][6][7][8][9] The design of catalysts for the asymmetric additions of organozinc reagents to aldehydes and ketones to give chiral alcohols has been the focus of intensive research and a large number of diverse catalysts have been developed. [10][11][12][13][14][15][16][17][18][19] Naturally occurring cinchona alkaloids and their derivatives have been widely used in a variety of asymmetric reactions with high catalytic efficiencies, [20][21][22][23][24][25][26][27][28] but they are less efficient [29][30][31][32] in the asymmetric organozinc addition reactions compared to other chiral ligands such as Walsh's HOCSAC [33][34][35][36][37][38][39] (a bis (hydroxycamphorsulfonamide) ligand derived from (R, R)-1,2-cyclohexyl diamine) and DAIB [40][41][42][43][44][45] (3-exo-dimethylaminoisoborneol). Herein, we report the development of a highly efficient trifunctional chiral phosphoramide-Zn(II) complex which can activate the asymmetric additions of diethylzinc with aldehydes to give desired alcohol products with excellent yields and enantiomeric excess (ee) values up...…”