Gold-catalyzed four-component multifunctionalization of alkynes

Abstract

The alkyne unit is a versatile building block in organic synthesis and the development of selective multifunctionalization of alkynes is an important object of research in this field. Herein, we report an interesting gold-catalyzed, four-component reaction that achieves the oxo-arylfluorination or oxo-arylalkenylation of internal aromatic or aliphatic alkynes, efficiently breaking a carbon-carbon triple bond and forming four new chemical bonds. The reaction divergence can be controlled by site-directing functional groups in the alkynes; the presence of a phosphonate unit favors the oxo-arylfluorination, while the carboxylate motif benefits oxo-arylalkenylation. This reaction is enabled by an Au(I)/Au(III) redox coupling process using Selectfluor as both an oxidant and a fluorinating reagent. A wide range of structurally diverse α,α-disubstituted ketones, and tri- or tetra-substituted unsaturated ketones have been prepared in synthetically valuable yields and with excellent chemo-, regio- and stereoselectivity. The gram-scale preparation and late-stage application of complex alkynes have further enhanced their synthetic value.

Gold–Manganese Bimetallic Redox Coupling with Light

“…Recently, our group , and others − have focused on the radical chemistry using Mn 2 (CO) 10 , which can smoothly generate short-lived • Mn­(CO) 5 radicals for the atom transfer process. Due to our continual interests in Au­(I)/Au­(III) redox coupling, − we posited that if we could make use of the • Mn­(CO) 5 radical as the key intermediate to proceed radical oxidative addition to the L–Au­(I)–X complex. We could finally produce a Mn–Au­(III)–Mn intermediate for bimetallic reductive elimination to furnish heterodinuclear complexes L–Au­(I)–Mn–L′ and L′–Mn–X as products (Figure b).…”