An unprecedented method that enables the direct coupling of an α-C–H bond in alcohols with 2-arylacetaldehydes through a [1,3]-hydride transfer ([1,3]-HT) of oxocarbenium ions catalyzed by a Lewis acid has been developed. The redox neutral preparation of the isochroman derivatives proceeds via a tandem condensation/[1,3]-HT/Friedel–Crafts sequence with moderate to good yields. Deuterium-labeling studies provide mechanistic insights and reveal that the redox functionalization proceeds via a [1,3]-HT.

The mimics of vitamin B6-dependent enzymes that catalyzed an enantioselective full transamination in the pure aqueous phase have been realized for the first time through the establishment of a new “pyridoxal 5′-phosphate (PLP) catalyzed non-covalent cyclodextrin (CD)-keto acid inclusion complexes” system, and various optically active amino acids have been obtained.

Alkenyl propargylic tertiary acetates were prepared by deprotonation of the corresponding enyne followed by nucleophilic addition to ketones and then treatment with acetic anhydride. The resulting acetates were then employed in diastereoselective [4+1] cycloadditions with CO catalyzed by [RhCl(CO)2]2 to form α-benzylidene cyclopentenone derivatives. We found the cycloadditions of the tertiary acetates to be more diastereoselective than those of the corresponding secondary acetates, as a result of increased substitution at the propargylic carbon. When an electron-donating meta substituent, such as Me and MeO, is introduced to the aryl group at the propargylic carbon of the tertiary acetate, the diastereoselectivity improved to >8:1 (E/Z).

•The method provided a concise methodology for the synthesis of chiral indolines.•An external hydride transfer agent was used for the KR of racemic indolines.•The reaction was good complementary to Akiyama’s work.We have developed a highly efficient and practical strategy for the kinetic resolution of indoline derivatives, involving a chiral Brønsted acid-catalyzed iminium ion formation and asymmetric transfer hydrogenation cascade process. The kinetic resolution allows the synthesis of 2-substituted N-benzylindolines in good yields with moderate to excellent enantioselectivities.Download high-res image (75KB)Download full-size image

A convenient method to synthesize various α-tertiary-hydroxy esters at room temperature has been developed. This method uses the readily available and inexpensive Zn powder in combination with an alkyl halide to promote the addition of alkynes to α-ketone esters with no need to exclude air or moisture. It has also been extended to promote the reaction of alkynes with a variety of aldehydes and other electron-deficient ketones.