Rh-Catalyzed Ortho C-H Alkynylation of Aromatic Aldehydes.

The Rh(III)-catalyzed ortho-alkynylation of benzaldehydes is enabled by the transient formation of an imine as a directing group. A broad scope of substrates was obtained under mild reaction conditions, granting access to mono- and dialkynylated products. The functionalization of readily available building blocks allowed the development of modular syntheses of dibenzopentalenes, isoquinolines, indoles, and indolines.