Copper-Catalyzed Carboarylation of Alkynes via Vinyl Cations

Abstract

Copper-catalyzed arylation of electron rich alkynes reveals stabilized trisubstituted vinyl cation equivalents that react with pendant arene nucleophiles to form all carbon tetrasubstituted alkenes. The new process streamlines the synthesis of important medicinally relevant molecules.

Formation of C(sp2)Boronate Esters by Borylative Cyclization of Alkynes Using BCl3

“…Previous work on electrophilic cyclization using iodonium salts only succeeded when the alkyne substituent was capable of electronically stabilizing the vinyl cation intermediate (e.g., p ‐MeOC 6 H 4 ‐functionalized alkynes) 17. Attempts at borylative cyclization of the terminal alkyne 4‐phenyl‐1‐butyne failed because of preferential haloboration with BCl 3 .…”

Diaryliodonium Salts in Organic Syntheses: A Useful Compound Class for Novel Arylation Strategies

“…[54][55][56][57][58][59][60][61][62][63][64][65][66][67] Utilizing this concept, several syntheses of diverse heterocyclic skeletons were developed in the last few years in our and other laboratories. The copper catalyzed synthesis of new oxazoline derivatives (89) from propargyl amides (88) and diaryliodonium salts was recently developed by our research group.…”

Formation of C(sp2)Boronate Esters by Borylative Cyclization of Alkynes Using BCl3

“…[17] Attempts at borylative cyclization of the terminal alkyne 4-phenyl-1-butyne failed because of preferential haloboration with BCl 3 .I n contrast, upon addition of BCl 3 ,the bromo-terminated alkyne 1p was converted into two products.P ost esterification the major product was the dihydronaphthalene, 2p (Scheme 2) and the minor component was that derived from haloboration of 1p (by GC-MS). Cyclization of an alkyl terminated alkyne, 1q,w as achieved with BCl 3 ,b ut in addition to the borylated dihydronaphthalene product (2q)aborylated naphthalene and tetralin were produced, consistent with transfer hydrogenation proceeding under these reaction conditions.…”