Cooperative Diarylborinic Acid/Chloride-Catalyzed Formal Si Reaction of -4-Hydroxymethyl-1,2-Cyclopentene Oxides.

A catalytic formal Si reaction was designed to achieve stereoretentive products for -4-hydroxymethyl-1,2-cyclopentene oxides by using diarylborinic acid as a dual role catalyst and chloride as a catalytic transient nucleophile through a double-displacement mechanism. This reaction offers the advantages of a low catalyst loading of 0.1 mol % and wide substrate scope, even including -substituents.

Palladium-catalyzed asymmetric hydrogenation of lactones under base-free conditions.

Asymmetric hydrogenation of esters through homogeneous catalysis is a significantly important transformation in organic synthesis. The systems developed so far mainly focused on chiral iridium and ruthenium catalysts, which required a base to facilitate the activity. Herein, we present a palladium-catalyzed asymmetric hydrogenation of lactones under base-free conditions through dynamic kinetic resolution and kinetic resolution.

Diarylborinic Acid-Catalyzed Ring Opening of -4-Hydroxymethyl-1,2-Cyclopentene Oxides: Synthesis of 1,2,4-Trisubstituted Cyclopentanes.

A diarylborinic acid-catalyzed ring opening of -4-hydroxymethyl-1,2-cyclopentene oxides was developed with -nucleophiles including anilines, benzotriazole, and alkylamines, as well as -nucleophiles, affording 1,2,4-trisubstituted cyclopentane compounds containing a quaternary carbon center. The mechanism study indicated that the "half-cage" structure formed by the epoxide substrate and the catalyst prevents the nucleophiles from attacking the inner side of the "half-cage", resulting in the desired ring-opening product.

Traceless-Activation Strategy for Rh-Catalyzed Csp-H Arylation of Coumarins.

A traceless-activation strategy for the synthesis of 4-arylchroman-2-ones via a Rh(III)-catalyzed C-H activation of 2-arylpyridines and subsequent conjugated/decarboxylative addition to coumarin-3-carboxylic acids has been reported. The carboxyl group at C3 position of coumarin proved to be crucial to realize the reaction, which is spontaneously removed after the reaction by the release of CO. The reaction displayed good substrate tolerance and gave various 4-arylchroman-2-ones in up to 90% yield.