From Tetrahydrofurans to Tetrahydrobenzo[d]oxepines via a Regioselective Control of Alkyne Insertion in Rhodium-Catalyzed Arylative Cyclization

Abstract

The formation of chiral 5- and 7-membered tetrahydrofurans and tetrahydrobenzo­[d]­oxepines is achieved via arylative cyclization of simple O-tethered alkyne-enoates in the presence of arylboronic acids and chiral dienes-rhodium catalyst under mild conditions. Access to such structures was achieved via a simple switch in the regioselectivity of the alkyne insertion thanks to a proper choice of the alkyne substituent.

Nickel‐Catalyzed Arylative Cyclizations of Alkyne‐ and Allene‐Tethered Electrophiles using Arylboron Reagents

“…13 C kinetic isotopic effect (KIE) experiments of a substrate at natural abundance revealed a significant 13 C KIE for Chemistry-A European Journal the nitrile carbon, suggesting that the addition to the nitrile (58 to 59) is likely the rate-determining step (RDS); however, the transmetalation step cannot be ruled out as the RDS. Finally, 31 P NMR studies suggested that water aids the transmetalation step.…”

“…Rhodium-, [19][20][21][22][23][24][25][26][27][28][29][30][31] palladium-, [32][33][34][35][36][37][38][39][40][41] or copper-catalyzed [42] arylative cyclizations of alkyne-tethered electrophiles involving 1,2arylmetallation of the alkyne to place the metal proximal to the electrophile, followed by direct intramolecular trapping of the intermediate alkenylmetal species with the tethered electrophile (see Scheme 1A), have been reported extensively. However, the use of catalyst systems based upon other metals are of interest because this could allow access to new reactivity and different reaction outcomes, with a consequent increase in scope.…”

“…Because of their generally good chemical stability, low toxicity, and widespread availability, arylboron compounds are commonly used as pronucleophiles in transition-metal-catalyzed domino carbometalation-cyclization reactions of alkyne- [60] or allene-tethered electrophiles. Arylative cyclization reactions of alkyne-tethered electrophiles involving an arylboron species have been described using rhodium, [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] palladium, [32][33][34][35][36][37][38][39][40][41] and copper catalysis. [42] Similarly, palladium-catalyzed arylative cyclization reactions of allene-tethered electrophiles involving arylboron reagents have been described.…”

“…These substrates ( 1 and 5 ) have been used in a wide range of transition‐metal catalyzed arylative and alkylative cyclization reactions to prepare diverse carbo‐ and heterocycles (Scheme 1). [6–44] These processes typically occur by the reaction of a pronucleophilic reagent with the transition‐metal catalyst to generate an organometallic species 2 . The alkyne or allene of the substrate then undergoes migratory insertion into this organometallic species to generate an alkenylmetal species 3 or allylmetal species 6 , respectively, which can then cyclize onto the tethered electrophile.…”

Indolylboronic Acids: Preparation and Applications

“…Several cyclizations of diverse substrates have been developed covering both indolylboronic acids and transition-metal catalysis. In 2019, the Darses research group developed a methodology for the asymmetric cyclization of (allyl)propargylether catalyzed by a rhodium catalyst (Scheme 43) [173]. The reaction is performed in methanol at 60 °C, and the reaction outcome depends on the structure of the ligand.…”