Rhodium-Catalyzed Asymmetric N2-C5 Allylation of Indazoles with Dienyl Allylic Alcohols.

The development of site-selective and regio- and enantioselective reactions of substrates with multiple active sites is an important topic and remains a substantial challenge in synthetic chemistry. Here, we describe a rhodium-catalyzed asymmetric N2-C5 allylation of indazoles with dienyl allylic alcohols under mild conditions. In the presence of a Rh/(P/olefin) catalyst and formic acid, chiral N2-C5 allylic indazoles were formed in good yields with excellent enantioselectivities (up to 97% ee). The mechanism proceeds through an elusive intermediate Int B, which represents a challenging task on asymmetric allylic substitution (AAS) of dienyl substrates.

Decarboxylative Cyclization of Ethynyl Benzoxazinanones with Imidazolidines to Access 2,3-Indole-Fused 1,4-Diazocines.

2,3-Indole-fused 1,4-diazocines represent a new family of indole alkaloid compounds and are difficult to access by the reported protocols. Herein, we report a copper-catalyzed decarboxylative cyclization of cyclic propargylic carbamates with imidazolidines via sequential C-N/C-N/C-C bond formation to deliver a series of 2,3-indole-fused 1,4-diazocines, with a broad substrate scope and mild conditions.

Access to Chiral Tetrahydroquinazolines/1,3-Benzoxazines via Iridium-Catalyzed Asymmetric [4 + 2] Cycloaddition.

An iridium-catalyzed asymmetric [4 + 2] cycloaddition of 1,3,5-triazinanes with 2-(1-hydroxyallyl)anilines/2-(1-hydroxyallyl)phenols has been developed, providing a straightforward and efficient approach to a wide range of tetrahydroquinazolines in good yields and excellent enantioselectivities (up to >99% ee). Typically, chiral 1,3-benzoxazines, which are challenging substrates in asymmetric [4 + 2] cycloaddition, could be obtained in excellent enantioselectivities via this protocol.