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The highly reactive Grignard reagents were introduced with bis[2-(N,N'-dimethylamino)ethyl] ether (BDMAEE) to effectively deactivate their reactivity and achieve a highly enantioselective alkylation of aldehydes with Grignard reagents from catalysis by (S)-BINOL-Ti[(O'Pr).sub.2]. The property of BDMAEE to chelate the in situ generated salts Mg[Br.sub.2] inhibits the catalytic activity of the Mg salts, suppresses the unwanted background reaction, and enables the highly enantioselective addition catalyzed by (S)-BINOL-Ti[(O'Pr).sub.2].

Tetrapeptides, containing a terminated primary amine and conformationally restricted D-Pro-Gly or D-Pro-Aib (2-aminoisobutanoic acid) segment as a segment [beta]-turn-nucleating element, are designed and prepared with condensation of N-module dipeptides with C-module dipeptides in solution. The asymmetric induction in the reaction of hydroxyacetone is not affected by solvents, and predominant anti products are achieved by tetrapeptide Val-D-Pro-Gly-Leu-OH in MeCN with the additive (S)-BINOL.

Natural primary amino acids were utilized to perform two step synthesis of seven primary amine organocatalysts and use them as catalyst for the direct asymmetric aldol reaction. The results revealed that the activities and enantioselectivities of the newly prepared inefficient primary amine organocatalysts could be elevated by using 2,4-dinitrophenol (DNP) as an effective cocatalyst.

The direct asymmetric aldol reaction of aryl ketones with aryl aldehydes catalyzed by chiral metal complex is reported. The method allows to synthesize two novel [C.sub.2]-symmetric semicrown ligands from chiral BINOL and (S)-diphenyl-prolinol.

The synthesis of the polymer-supported 1,1'-bi-2-naphthol has been carried out. Results demonstrate that the new ligand is more enantioselective than its analog.

Tetrapeptides, containing a terminated primary amine and conformationally restricted D-Pro-Gly or D-Pro-Aib (2-aminoisobutanoic acid) segment as a strongly β-turn-nucleating element, were designed and synthesized with condensation of N-module dipeptides with C-modules dipeptides in solution. They were first applied to catalyze aldol reactions, and were found to be effective catalyst for the transformations. The tetrapeptide Val-D-Pro-Gly-Leu-OH (1g) was the optimal organocatalyst. It was shown that the intensive β-turn conformation, indicated by CD and NOESY spectra, contributed to the (R)-aldol and high enantioselectivity of the reaction of acetone in MeOH, whereas the sharply varied conformation should contribute to the low enantioselectivity and (S)-product of the reaction in 1,2-dichloroethane (DCE). The asymmetric induction in the reaction of hydroxyacetone was not affected by solvents, and predominant anti products were achieved by 1g in MeCN with the additive (S)-BINOL. [ABSTRACT FROM AUTHOR]

A correction to the article "Catalytic Highly Enantioselective Alkylation of Aldehydes with Deactivated Grignard Reagents and Synthesis of Bioactive Intermediate Secondary Arylpropanols," which was published in a 2010 issue is presented.

Because of the high reactivity of Grignard reagents, a direct, highly enantioselective Grignard reaction with aldehydes has rarely been disclosed. In this report, Grignard reagents were introduced with bis[2-(N,N'-dimethylamino)ethyl] ether (BDMAEE) to effectively deactivate their reactivity; thus, a highly enantioselective alkylation of aldehydes with Grignard reagents resulted from catalysis by (S)-BINOL-Ti(O(i)Pr)(2). It is thought that BDMAEE chelates the in situ generated salts MgBr(2) from a Schlenk equilibrium of RMgBr and Mg(O(i)Pr)Br from transmetalation of RMgBr with Ti(O(i)Pr)(4). The Mg salts can actively promote the undesired background reaction to give the racemate. The chelation definitely inhibits the catalytic activity of the Mg salts, suppresses the unwanted background reaction, and enables the highly enantioselective addition catalyzed by (S)-BINOL-Ti(O(i)Pr)(2). Consequently, the Mg salt byproducts were not removed, less Ti(O(i)Pr)(4) than RMgBr was used, and extremely low temperature was avoided in this catalytic asymmetric reaction in comparison with the research disclosed before. Various alkyl Grignard reagents were investigated in the asymmetric addition, and (i)BuMgBr resulted in the highest enantioselectivity, >99%. Furthermore, important intermediate secondary arylpropanols for chiral drug synthesis were effectively synthesized with high enantioselectivity, up to 97%, in one step.