Palladium‐Catalyzed Asymmetric Aminohydroxylation of 1,3‐Dienes

A Pd^II‐catalyzed asymmetric aminohydroxylation of 1,3‐dienes with N‐tosyl‐2‐aminophenols was developed by making use of a chiral pyridinebis(oxazoline) ligand. The highly regioselective reaction provides direct and efficient access to chiral 3,4‐dihydro‐2H‐1,4‐benzoxazines in high yield and enantioselectivity (up to 96:4 e.r.). The reaction employs readily available N‐tosyl‐2‐aminophenols as a unique aminohydroxylation reagent and is complementary to known asymmetric aminohydroxylation methods.     

Regiodivergent Copper Catalyzed Borocyanation of 1,3‐Dienes

Copper catalyzed multi‐functionalization of unsaturated carbon‐carbon bonds is a powerful tool for the generation of complex molecules. We report a regiodivergent process that allows a switch between 1,4‐borocupration and 4,1‐borocupration of 1,3‐dienes upon a simple change in ligand. The subsequently generated allyl coppers are trapped in an electrophilic cyanation to selectively generate densely functionalized and synthetically versatile 1,2‐ or 4,3‐borocyanation products.     

Ruthenium‐Catalyzed Multicomponent Reactions: Access to α‐Silyl‐β‐Hydroxy Vinylsilanes,Stereodefined 1,3‐Dienes,and Cyclohexenes

The synthesis of densly functionized α‐silyl‐β‐hydroxyl vinylsilanes via ruthenium‐catalyzed multicomponent reaction (MCR) is reported herein. Exceptionally high regio‐ and diastereoselectivity was achieved by employing an unprecedented hydrosilylation of bifunctional silyl‐propargyl boronates. The simple protocol, mild reaction conditions, and unique tolerability of this method make it a valuable tool for the synthesis of highly elaborated building blocks. The one‐pot synthesis of stereodefined olefins, the generation of a valuable cyclohexene building block through a four‐component MCR, and further functionalization in an abundance of diastereoselective reactions is disclosed herein.     

Highly Diastereo‐ and Enantioselective Cu‐Catalyzed Borylative Coupling of 1,3‐Dienes and Aldimines

A Cu‐catalyzed diastereo‐ and enantioselective borylative coupling reaction of 1,3‐dienes with imines was realized. Branched homoallylic amines are readily prepared in a syn‐selective manner with high regio‐, diastereo‐ and enantioselectivity. Moreover, these three‐component coupling reactions feature good functional‐group compatibility and easy access to the substrates and catalyst.