Chiral Pincer Carbodicarbene Ligands for Enantioselective Rhodium-Catalyzed Hydroarylation of Terminal and Internal 1,3-Dienes with Indoles

Abstract

Catalytic enantioselective addition of N-heteroarenes to terminal and internal 1,3-dienes is reported. Reactions are promoted by 5 mol % of Rh catalyst supported by a new chiral pincer carbodicarbene ligand that delivers allylic substituted arenes in up to 95% yield and up to 98:2 er. Mechanistic and X-ray evidence is presented that supports that the reaction proceeds via a Rh(III)-η-allyl.

Observation of Carbodicarbene Ligand Redox Noninnocence in Highly Oxidized Iron Complexes

“…Since the original reports of CDCs, significant efforts have been expended to elaborate their backbones to modulate their steric and electronic properties, expand beyond the presently predominant NHC donors, and to incorporate them into multidentate ligand frameworks . Thus far, CDCs have mainly been utilized in stabilization of otherwise unobtainable low‐coordinate main‐group species and as surrogates for carbene ligands in various transition‐metal‐catalyzed reactions ,…”

Asymmetric [3+2] Cycloaddition of Olefins with Morita–Baylis–Hillman Carbonates Catalyzed by BINOL-Based Bifunctional Phosphine

“…The reaction mixture was stirred overnight and then filtered. The resulting mixture was concentrated and purified by a silica gel flash chromatography (PE/DCM/EtOAc = 4:1:1) to afford compound 1c as white foam solid (72.4 mg, 41% yield 1,133.4,133.3,133.1,132.8,132.6,132.6,132.2,131.7,131.5,130.6,129.8,129.0,128.8,128.6,128.6,128.6,128.4,128.4,127.2,126.7,126.0,125.9,125.6,124.1,124.0,121.1,61.3 (d,J = 18.6 Hz), 53.5, 52.9, 33.9 (d, J = 12.7 Hz), 31.9 (d, J = 8.4 Hz), 22.5, 21.5, 21.5; 31 P NMR (162 MHz, CDCl3) δ -20.9; ESI-HRMS: calcd. for C52H47NO6PS2 + (M+H) + 876.2577, found 876.2587.…”

“…Compound 6a: Known compound 4 ; White solid, 47.9 mg, 85% yield, 74%ee; Purified by silica gel flash column chromatography (Hexane/EtOAc = 10:1); 1…”

Chemoselective Synthesis of Z‐Olefins through Rh‐Catalyzed Formate‐Mediated 1,6‐Reduction

“…[11] Herein, we report af ormate-mediated reduction of activated dienes to generate Z-olefins. [12] Substrate coordination and hydride delivery from aRhcatalyst dictate achemoand regioselective process.Other unsaturated groups such as non-activated olefins or dienes, a,b-unsaturated esters,i nternal alkynes,a nd ah ost of electrophilic groups are tolerated ( Figure 1). Thep rocess offers an ew opportunity to prepare polyfunctionalized Z-olefins in complex substrate environments without protecting groups.…”