An efficient and straightforward Lewis-acid-mediated stereoselective (4 + 3)-cyclization of indole-substituted alkylidene malonates and donor−acceptor cyclopropanes has been developed involving the Friedel−Crafts/Michael addition cyclization cascade. This reaction provides a mild and effective method for the construction of synthetically and structurally interesting functionalized cycloheptannelated indoles.

A novel Brønsted acid catalyzed 1,8-addition mediated (3 + 4)-annulation of in situ generated propargylic p-quinone methides with 2-indolylmethanols is described. This method provides a convenient and mild approach to structurally interesting and synthetically important polysubstituted indole-fused oxepines in high yields. Moreover, 2-indolylmethanols as four-atom synthons in the (3 + 4)-annulations under Brønsted acid conditions have been explored for the first time.

Chiral acyclic all-carbon quaternary stereocenters are widely present in natural products and pharmaceuticals. However, their introduction remains a challenging topic in the synthetic research community. Here, we report an efficient metalfree method for the construction of acyclic all-carbon quaternary chiral centers sited at the α-position of an aldehyde or ketone moiety. This is achieved via a well-designed reaction cascade involving arylalkynes, benzoquinones, and electron-rich (hetero)arenes and the use of visible light and phosphoric acid catalysis. Notably, the asymmetric catalytic visible-light-induced Paterno−Buchi cycloaddition/electrocyclic ring-opening/α-selective arylation of α,β-unsaturated carbonyl compound cascades is achieved. Moreover, the reaction works well for a broad range of these three components (>70 examples). Furthermore, the rich chemistry embedded in the products provides a variety of synthetically useful building blocks that are otherwise difficult to access. Lastly, the origin of enantioselectivity was investigated by density functional theory, revealing that CH/π interactions play a crucial role in the stereocontrol of the reaction.

Herein, we report an efficient Brønsted acid-catalyzed formal (3+3)-annulation of (aza)-para-quinone methides generated in situ from propargylic alcohols with naphthol derivatives, which involves a 1,8-conjugate addition/6-endo annulation process. This protocol provides an effective method for preparing important functionalized pyranocoumarins under mild conditions.

An efficient and straightforward Brønsted acid mediated (3+2)-annulation of (aza)-para-quinone methides, generated in situ from propargylic alcohols and indoles, has been developed involving 1,8-conjugate addition/5-endo annulation cascade. This protocol affords a mild and effective method for the construction of synthetically important and structurally interesting functionalized pyrrolo[1,2-a]indoles.