Enantioselective Alkylation of Aldehydes Catalyzed by a Highly Active Titanium Complex of 3‐Substituted Unsymmetric BINOL.

Harada, Toshiro; Kanda, Kousou

doi:10.1002/chin.200651027

Cited by 3 publications

(3 citation statements)

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“…[23][24][25][26] Recently Harada and Kanda reported that 3-substituted BINOLs exhibited an enhanced catalytic activity compared to 3,3 0 -disubstituted BINOLs in the reaction. 27 Similar phenomena also appeared in our previous research. 28,29 On the basis of this research, a new kind of chiral ligands exhibiting an enhanced asymmetric catalytic activity could possibly be obtained by introducing amino and imino groups into the 3-position of BINOL through the methylene bridge.…”

Section: Introductionsupporting

confidence: 75%

3‐Substituted BINOL Schiff bases and their reductive products for catalytic asymmetric addition of diethylzinc to aldehydes

et al. 2008

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Section: Introductionsupporting

confidence: 75%

3‐Substituted BINOL Schiff bases and their reductive products for catalytic asymmetric addition of diethylzinc to aldehydes

et al. 2008

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“…In addition, the same stereochemistry for products derived from addition reactions of organozinc, Grignard, organolithium, organoaluminum, or organotitanium compounds suggests that the catalytic reactions involve acitve species with similar structures which are proposed to be dititanium species I containing one BINOLate ligand and the nucleophile. 11,24,33,36,38 …”

Section: Resultsmentioning

confidence: 98%

Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)‐h₈‐binol

Li¹,

Gau²

2011

Chirality

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Three alkyltitanium reagents of RTi(O-i-Pr)3 (R = Cy (1a), i-Bu (1b), and n-Bu (1c)) were prepared in good yields. The high-resolution mass spectroscopy showed that and 1c in the gas phase are monomeric species. However, the solid state of 1a revealed a dimeric structure. Asymmetric additions of 1a-1c to aldehydes catalyzed by a titanium catalyst of (R)-H8 -BINOL were studied at room temperature. The reactions produced desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 94% ee. Reactivity and enantioselectivity differences, in terms of steric bulkiness of the R nucleophiles, are herein described. The addition reactions of secondary c-hexyl to aldehydes were slower than the reactions of primary i-butyl or n-butyl nucleophiles. For the primary alkyls, lower enantioselectivities were obtained for products from addition reactions of the linear n-butyl as compared with the enantioselectivities of products from the addition reactions of the branched i-butyl group. The same stereochemistry of RTi(O-i-Pr)3 addition reactions as the addition reactions of organozinc, organoaluminum, Grignard, or organolithium reagents directly supports the argument of that titanium-catalyzed addition reactions of aldehydes involve an addition of an organotitanium nucleophile.

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“…Therefore, numerous kinds of chiral ligands, such as amino alcohols ( N , O ‐ligands), diamines ( N , N ‐ligands), and diols ( O , O ‐ligands) have been designed and evaluated in the catalytic asymmetric addition of diethylzinc to aldehydes 24–31. As an important O , O ‐ligand, BINOL and its derivatives have been widely studied and earned a prominent status because of their outstanding performance in a good number of asymmetric reactions 32–39…”

Section: Introductionmentioning

confidence: 99%

Synthesis and application of 3‐substituted (S)‐BINOL as chiral ligands for the asymmetric ethylation of aldehydes

Zhang

Dong

2010

Chirality

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A series of (S)-BINOL ligands substituted at the 3 position with some five-membered nitrogen-containing aromatic heterocycles were effectively prepared and their catalytic abilities were evaluated in the asymmetric addition of diethylzinc to benzaldehyde in the presence of titanium tetraisopropoxide. Under the optimized reaction conditions, titanium complex of (S)-3-(1H-benzimidazol-1-yl)-1,1'-bi-2-naphthol was found to be the most efficient catalyst for asymmetric ethylation of various aldehydes to generate the corresponding secondary alcohols in up to 99% yield and 91% ee.

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Enantioselective Alkylation of Aldehydes Catalyzed by a Highly Active Titanium Complex of 3‐Substituted Unsymmetric BINOL.

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 3 publications

References 6 publications

3‐Substituted BINOL Schiff bases and their reductive products for catalytic asymmetric addition of diethylzinc to aldehydes

3‐Substituted BINOL Schiff bases and their reductive products for catalytic asymmetric addition of diethylzinc to aldehydes

Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)‐h₈‐binol

Synthesis and application of 3‐substituted (S)‐BINOL as chiral ligands for the asymmetric ethylation of aldehydes

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Enantioselective Alkylation of Aldehydes Catalyzed by a Highly Active Titanium Complex of 3‐Substituted Unsymmetric BINOL.

Abstract: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Cited by 3 publications

References 6 publications

3‐Substituted BINOL Schiff bases and their reductive products for catalytic asymmetric addition of diethylzinc to aldehydes

3‐Substituted BINOL Schiff bases and their reductive products for catalytic asymmetric addition of diethylzinc to aldehydes

Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)‐h8‐binol

Synthesis and application of 3‐substituted (S)‐BINOL as chiral ligands for the asymmetric ethylation of aldehydes

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Room temperature and highly enantioselective additions of alkyltitanium reagents to aldehydes catalyzed by a titanium catalyst of (R)‐h₈‐binol