Rhodium(ii)-catalysed generation of cycloprop-1-en-1-yl ketones and their rearrangement to 5-aryl-2-siloxyfurans

Abstract

Donor-acceptor cyclopropenes formed from enoldiazoketones undergo catalytic rearrangement to 5-aryl-2-siloxyfurans via a novel mechanism that involves a nucleophilic addition of the carbonyl oxygen to the rhodium-activated cyclopropene.

Catalytic asymmetric cycloaddition reactions of enoldiazo compounds

“…Enoldiazoketones are the most reactive of the enoldiazocarbonyl compounds, undergoing catalyst-free dinitrogen extrusion even at room temperature. Their D-A cyclopropenes are also reactive, and they readily undergo rearrangement to furan derivatives under dirhodium(II) catalysis 75 which, because of this, complicates cycloaddition with this undesirable competing reaction. 39 Enoldiazosulfones and their D-A cyclopropenes are thermally the most stable in this series; however, its silyl group is unstable to hydrolysis.…”

C–C Bond Cleavages of Cyclopropenes: Operating for Selective Ring-Opening Reactions

“…Using the corresponding 3-alkoxycarbonyl­cyclopropenes 151 , the analogous regiodivergent synthesis of 2-alkoxyfurans 152 and 153 was later reported by the same group (Scheme C). , Optimal results in terms of selectivity were obtained by employing Cu­(acac) 2 or [RuCl 2 (PPh 3 ) 3 ] as they provided furans 152 and 153 , respectively, as exclusive isomers. This transformation showed also a satisfactory scope and synthetically useful yields.…”

Synthetic Applications of Cyclopropene and Cyclopropenone: Recent Progress and Developments

“…In 1991, Larock and co-workers [54] developed a palladium catalyzed regioselective formation of 2,3-disubstituted indoles by using internal alkynes and 2-iodoaniline. 2,3-disubstituted indole is a key pharmacophore of various biologically active natural and unnatural molecules and the chemists were curious to find out a suitable synthetic procedure to provide 2,3disubstituted indole with excellent regioselectivity.…”

“…2,3-disubstituted indole is a key pharmacophore of various biologically active natural and unnatural molecules and the chemists were curious to find out a suitable synthetic procedure to provide 2,3disubstituted indole with excellent regioselectivity. [54] In 2019, Wang's team [55] put effort and interest in the field of both indole derivatives and small ring compounds and developed a method for synthesis of 2,3-disubstituted indoles from [3 + 2] annulation of donor-acceptor cyclopropenes with anilines. They have also reported a Ni-catalyzed regioselective synthesis of 2,3-functionalized indoles 105 via [3 + 2] annulation of donor-acceptor 2bromocyclopropenes 100 with N-substituted anilines 101 in good to high yields with excellent regioselectivity.…”