Rhodium-catalyzed C(sp2)–H Addition of Arylboronic Acids to Alkynes Using a Boron-based, Convertible ortho-Directing Group

Temporary modification of a boronyl group with pyrazorylaniline allowed insertion of arylpropiolates and diphenylacetylenes into the o-C–H bond of arylboronic acids in the presence of rhodium catalysts, giving 3,3-diarylacrylates and triarylethene containing aryl groups bearing an o-boryl group stereoselectively. The boronyl group in the 3,3-diarylacrylates was converted into various functional groups, including chlorine, hydrogen, hydroxy, and aromatic groups.Using pyrazorylaniline as an ortho-directing group on boron, 3,3-diarylacrylates and triarylethenes containing an o-borylated aryl group were synthesized via rhodium-catalyzed C(sp2)–H addition of arylboronic acids to alkynes followed by replacement of the directing group with pinacol. A versatile conversion of the boronyl group afforded 3,3-diarylacrylates bearing an o-functionalized benzene ring containing hydrogen, phenyl, chloro, and hydroxy groups.