Rhodium‐Catalyzed Arylation of Cyclopropenes Based on Asymmetric Direct Functionalization of Three‐Membered Carbocycles

Abstract

Avariety of highly diastereo-and enantiomerically enriched arylcyclopropanes is obtained through the asymmetric rhodium-catalyzed arylation reaction of achiral nonfunctionalized cyclopropene derivatives with commercially available aryl boronic acids in the presence of (R,S)-Josiphos. Scheme 1. Asymmetric direct functionalization of three-membered carbocycles as anew approach to diastereo-and enantiomerically enriched cyclopropanes.

Asymmetric Preparation of Polysubstituted Cyclopropanes Based on Direct Functionalization of Achiral Three-Membered Carbocycles

“…The diastereo-and enantioselective Josiphos/Rh-catalyzed asymmetric arylation reactions of cyclopropene derivatives with commercially available aryl boronic acids provide the arylated cyclopropanes 27 in excellent diastereo-and enantiomeric ratios (Scheme 22). 132 Aryl boronic acids containing electron-donating or electron-withdrawing groups could be used indifferently as they have nearly no influence on the diastereoselectivity and enantioselectivity of the catalytic reaction. Even aryl boronic acid containing a NO 2 moiety, fluorine substituents, or a trifluoromethyl group gave the desired arylated products with high selectivities.…”

A catalytic asymmetric cross-coupling approach to the synthesis of cyclobutanes

“…Reductive Heck reactions of unfunctionalised alkenes that utilize the release of olefinic-strain have been reported for cyclopropenes (27.7 kcal/mol) 27,28 and (di-)azabicycles (for norbornene: 4.8 kcal/mol) [28][29][30] and also hydroarylation of pyrrolines is known 31 . These reports stimulated our interest in whether the relatively small olefinic-strain of cyclobutenes (1.9 kcal/mol) 28 is sufficient to drive rhodium-catalysed arylation of cyclobutenes.…”

Cobalt-Catalyzed Diastereoselective and Enantioselective Hydrosilylation of Achiral Cyclopropenes

“…In the past few years, the catalytic diastereo- and enantioselective direct functionalization of achiral three-membered carbocycles, 7 as an alternative approach to the cyclopropanation of olefins, 8 − 10 has attracted significant attention as a new source of enantioenriched polysubstituted cyclopropanes from a common and unique starting material. Using such a direct functionalization strategy, a large variety of nucleophiles—alkyl, 11 alkenyl, 12 aryl, 13 alkynyl, 14 boronyl, 15 carbonyl, 16 stannyl 17 among others 18 —were selectively added on the three-membered ring ( Scheme 1 a). With the idea of extending the toolbox available to practitioners, we noticed that the catalytic and enantioselective preparation of silylcyclopropanes from unfunctionalized cyclopropenes was less developed until very recent reports from Oestreich 19 and Xu.…”