A series of Schiff base ligands were synthesized from (1R)-camphor. Under the optimal conditions, (+)-SBAIB-a, 10 was found to be an excellent catalyst for the enantioselective addition of phenylacetylene to various aldehydes without utilizing either achiral additives or Ti(O(i)Pr)(4). This approach yielded (R)-propargylic alcohols in extremely high yields (up to 99%) and excellent enantioselectivities (up to 92%). The corresponding (S)-propargylic alcohols were synthesized in good to high enantioselectivities (up to 91%) and excellent yields (up to 99%) using (-)-SBAIB-a, 41.

A new bifunctional copper complex of the aminoisoborneol Schiff base -Cu 2 A C H T U N G T R E N N U N G (SBAIB-d) 2 -has been developed for the effective direct catalytic asymmetric Henry reaction. One mol% of this catalyst produces the expected Henry products in high yields (up to 99%) with excellent enantioselectivities (up to 98% ee). The utility of the present catalyst was also extended to the Henry reaction with nitroethane and 1-nitropropane that furnished the corresponding products in moderate to high yields (up to 99%) with moderate to high enantioselectivities of syn (up to 98% ee) and anti (up to 98% ee) diastereomers. The highlights of this catalytic system are easy manipulation, air and moisture tolerance, the need for 1 mol% of an easily synthesizable catalyst and the high enantioselectivities achieved for a wide range of substrates.

Novel in situ formed vanadium Schiff base complexes, namely vanadyl Schiff base of 3-exo-aminoisoborneol (V(O)-SBAIB) and vanadyl Schiff base of 3-endo-aminoborneol (V(O)-SBAB), were demonstrated to catalyze an enantioselective sulfoxidation reaction. Among the twenty substitutionally and electronically different (1R)-camphor based Schiff base ligands, 6-bromo-2hydroxy-1-naphthaldehyde Schiff base of 3-endo-aminoborneol, 48 (SBAB-14), produced (S)-ethyl 2-naphthyl sulfoxide in excellent enantioselectivity (> 99 %) with good yield (72 %). In an optimized reaction condition, 1.5 mol% 48 (SBAB-14) catalyzed asymmetric sulfoxidation with concomitant kinetic resolution of various alkyl aryl sulfides and rendered corresponding sulfoxides with high ee (up to 97 %) with moderate yield (up to 74 %).[a] T.Figure 1. Structure of Schiff base ligands that applied in vanadium catalyzed asymmetric sulfoxidation.

The nascency of second-generation sulfur-stabilized borenium cations by halophilic Lewis acid SnCl 4 leads to highly active chiral Lewis acids that are very effective catalysts for [4 + 2] cycloaddition. Oxathiaborolium pentachlorostannate (5−10 mol %) successfully catalyzed cycloaddition of various dienes and dienophiles to afford cycloadducts with excellent enantioselectivity (20 examples, up to 99% ee). This super Lewis acid also exhibited good enantioselectivity for the first Lewis acid coordinated and chiral Lewis acid catalyzed [4 + 2] cycloaddition to α,β-unsaturated mixed ester amide. Letter pubs.acs.org/OrgLett

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