Rh-catalyzed C–C bond cleavage by transfer hydroformylation

Abstract

The dehydroformylation of aldehydes to generate olefins occurs during the biosynthesis of various sterols, including cholesterol in humans. Here, we implement a synthetic version that features the transfer of a formyl group and hydride from an aldehyde substrate to a strained olefin acceptor. A Rh(Xantphos)(benzoate) catalyst activates aldehyde C–H bonds with high chemoselectivity to trigger C–C bond cleavage and generate olefins at low loadings (0.3 to 2 mol%) and temperatures (22 to 80 °C). This mild protocol can be applied to various natural products and was used to achieve a three step synthesis of (+)-yohimbenone. A study of the mechanism reveals that the benzoate counterion acts as a proton-shuttle to enable transfer hydroformylation.

Toward a mild dehydroformylation using base-metal catalysis

“…3). 13 While such reactivity had been observed previously, this catalyst system represents a significant improvement over the earlier methods, where yields were low, ester side products were observed, and the reaction had to be performed at high temperature and high pressure of carbon monoxide. 8 In the wake of that development, Nozaki and coworkers described a method of acceptorless dehydroformylation using a carefully engineered iridium complex to produce olefins with H 2 and CO as the sole by-products.…”

Observation of Spontaneous C=C Bond Breaking in the Reaction between Atomic Boron and Ethylene in Solid Neon

“…[1][2][3][4] This reaction opened the way to the development of catalytic methods for the controlled modification of molecules at the site of aC ÀHb ond. [6][7][8][9][10] Ther eactions of atomic atoms with simple hydrocarbons serve as the prototypical models to understand the thermochemistry,mechanism, and periodic trends of CÀHa nd CÀC bond activations.T he elementary reactions of metal atoms with simple hydrocarbons have been intensively investigated [11,12] using matrix isolation spectroscopy,apowerful method for delineating reaction mechanisms through the isolation and characterization of reactive intermediates. [6][7][8][9][10] Ther eactions of atomic atoms with simple hydrocarbons serve as the prototypical models to understand the thermochemistry,mechanism, and periodic trends of CÀHa nd CÀC bond activations.T he elementary reactions of metal atoms with simple hydrocarbons have been intensively investigated [11,12] using matrix isolation spectroscopy,apowerful method for delineating reaction mechanisms through the isolation and characterization of reactive intermediates.…”

Theoretical studies of nickel-catalyzed ring-opening hydroacylation of methylenecyclopropanes and benzaldehydes

“…Transition-metal-catalyzed functionalization of C-H bonds is a rapidly growing field in synthetic organic chemistry and organometallic chemistry that enables efficient access to a wide variety of building blocks [1][2][3][4][5][6][7]. Transition-metalcatalyzed hydroacylation is one of the most useful C-H bond activation processes, and has become increasingly important in recent organic synthesis because of growing demands for efficient, ordinary, green, atom-economical processes [6][7][8].…”