Highly Enantioselective Rhodium(I)‐Catalyzed Carbonyl Carboacylations Initiated by CC Bond Activation

Abstract

The lactone motif is ubiquitous in natural products and pharmaceuticals. The Tishchenko disproportionation of two aldehydes, a carbonyl hydroacylation, is an efficient and atom-economic access to lactones. However, these reaction types are limited to the transfer of a hydride to the accepting carbonyl group. The transfer of alkyl groups enabling the formation of CC bonds during the ester formation would be of significant interest. Reported herein is such asymmetric carbonyl carboacylation of aldehydes and ketones, thus affording complex bicyclic lactones in excellent enantioselectivities. The rhodium(I)-catalyzed transformation is induced by an enantiotopic CC bond activation of a cyclobutanone and the formed rhodacyclic intermediate reacts with aldehyde or ketone groups to give highly functionalized lactones.

Enantioselective Rh-Catalyzed Carboacylation of C═N Bonds via C–C Activation of Benzocyclobutenones

“…1o Pioneering work by Cramer and coworkers demonstrated the first and asymmetric example of Rh-catalyzed carboacylation of aldehydes and ketones via enantiotopic C–C activation of cyclobutanones to access bridged lactones (Scheme 1A). 3 Recently, the same group showed the same transformation can also be catalyzed by Lewis acids. 4 …”

“Cut and Sew” Transformations via Transition-Metal-Catalyzed Carbon–Carbon Bond Activation

“…63 The reaction was found to tolerate a number of cyclobutanone-substituted moieties as well as aldehyde and ketone insertion partners. Aldol condensation and cyclopropane formation from decarbonylation of cyclobutanones were observed as common side reactions.…”

Ruthenium‐ and Rhodium‐Catalyzed Strain‐Driven Cleavage and Reconstruction of the C–C Bond

“…I -catalyzed intramolecular formal [4+2] cycloaddition reactions of cyclobutanone with tethered C=C [14] and C=O bonds [15] have since been reported. Most recently, Cramer reported the regiodivergent ring-opening of 3-(2-alkanoylphenyl)cyclobutanones by employing the appropriate choice of the Lewis acid catalysts Cu(OTf ) 2 (OTf = trifluoromethanesulfonate) or SnCl 4 to give the corresponding indenylacetic acids and benzoxabicyclo[3.2.1]octane-3-ones, respectively, in high yields.…”