Rhodium(III)‐Catalyzed Enantio‐ and Diastereoselective C−H Cyclopropylation of N‐Phenoxylsulfonamides: Combined Experimental and Computational Studies

Abstract

Cyclopropane rings are aprominent structural motif in biologically active molecules.E nantio-and diastereoselective construction of cyclopropanes through C À Hactivation of arenes and coupling with readily available cyclopropenes is highly appealing but remains ac hallenge.Adual directinggroup-assisted CÀHactivation strategy was used to realizemild and redox-neutral Rh III -catalyzed CÀHa ctivation and cyclopropylation of N-phenoxylsulfonamides in ah ighly enantioselective,d iastereoselective,a nd regioselective fashion with cyclopropenyl secondary alcohols as ac yclopropylating reagent. Synthetic applications are demonstrated to highlight the potential of the developed method. Integrated experimental and computational mechanistic studies revealed that the reaction proceeds via aR h V nitrenoid intermediate,a nd Noyori-type outer sphere concerted proton-hydride transfer from the secondary alcohol to the Rh = Nb ond produces the observed trans selectivity. Figure 3. Optimized geometries,e nergy differences and ee values of the transitions tates TS3 SS and TS3 RR for the alkene insertion step in the (R)-Rh4-catalyzed cyclopropanation reaction.

Rhodium(III)‐Catalyzed Asymmetric [4+1] and [5+1] Annulation of Arenes and 1,3‐Enynes: A Distinct Mechanism of Allyl Formation and Allyl Functionalization

“…While the 1,4‐rhdoium migration pathway cannot be ruled out experimentally, this migration, if present, most likely follows a σ‐bond metathesis pathway so as to avoid H/D exchange with external deuterium sources [8] . In addition, the observed intraligand H/D exchange may also suggest relevance of rhodium hydride intermediate that rapidly undergoes subsequent transformation (insertion) to scramble the H and D atoms while avoiding H/D exchange with external deuterium sources [22] . The current mechanism stays in sharp contrast to a reversible protonolysis/C−H activation proposal in previous studies, [7, 9] and our H/D exchange studies also provided important experimental basis for the DFT studies.…”

Rhodium(III)‐Catalyzed Atroposelective Synthesis of Biaryls by C−H Activation and Intermolecular Coupling with Sterically Hindered Alkynes

“…Several experiments have been carried out to explore the reaction mechanism. Stoichiometric C−H activation of 1 a with Rh‐1 in the presence of AgOAc, followed by addition of PPh 3 , allowed isolation of the rhodacycle 11 in high yield (Scheme a) . The complex 11 was characterized by NMR spectroscopy and X‐ray crystallography (CCDC 1978298 contains the supplementary crystallographic data for this paper.…”

Applications of Chiral Cyclopentadienyl (Cpx) Metal Complexes in Asymmetric Catalysis

“…The group of Li accessed cyclopropanes via a Rh-catalysed C-H functionalisation of Nphenoxylsulfonamides 98. [58] Using cyclopropenyl alcohols 99 as coupling partners, a broad scope of substrates were reacted in high yields and enantioselectivities (Scheme 20b). an oxime directing group (107) with 2,3-diazabicyclo[2.2.1] alkenes 108 (Scheme 21b).…”