Methylenecyclopropane Annulation by Manganese(I)‐Catalyzed Stereoselective C−H/C−C Activation

Abstract

C-H/C-C functionalizations with methylenecyclopropanes (MCPs) were accomplished with a versatile base-metal catalyst. A robust manganese(I) complex enabled the expedient annulation of MCPs by synthetically meaningful ketimines to deliver, upon one-pot hydroarylation, densely substituted polycylic anilines in a step-economical fashion. Mechanistic studies provided strong support for a facile organometallic C-H manganation, while typical cobalt, ruthenium, rhodium, and palladium catalysts were found completely ineffective.

A Stereodynamic Redox‐Interconversion Network of Vicinal Tertiary and Quaternary Carbon Stereocenters in Hydroquinone–Quinone Hybrid Dihydrobenzofurans

“…[1,2] When combined, hydroquinones and quinones form charge-transfer complexes called quinhydrones [3] that undergo reversible redox exchange [4] ( Figure 1A,r ight), and have been studied as cofactors in artificial photosystem mimics. [5] In molecules that contain both hydroquinone and quinone groups ( Figure 1B,l eft and middle), [6,7] this dynamic redox behavior can result in facile enantiomerization in cases where both hydroquinone and quinone are substituents at the same stereogenic center ( Figure 1B,r ight). [8] This phenomenon of dynamic stereochemistry, [9][10][11][12][13] when afunction of redox chemistry, [14] has also been observed with helical chirality in copper complexes upon reversible change of oxidation state.…”

Methylenecyclopropane Annulation by Manganese(I)‐Catalyzed Stereoselective C−H/C−C Activation

“…Forthe X-ray structure, the anisotropic displacement parameters are shown at 50 %p robability. [20] Scheme 6. Proposed catalytic cycle for CÀH/CÀCfunctionalization.…”

“…[ a] Without ZnCl 2 .F or the X-ray structure, the anisotropic displacement parameters are shown at 50 %p robability. [20] Scheme 3. CÀH/CÀCactivation with the substituted MCPs 2.…”

Exploiting Strained Rings in Chelation Guided C−H Functionalization: Integration of C−H Activation with Ring Cleavage

“…In 2013, Cui and co‐workers reported Rh III ‐catalyzed cycloaddition of benzamides with MCPs, for the selective synthesis of spiro quinolinones and furan‐fused azepinones (Scheme ) . Later Ackermann and co‐workers accomplished stereoselective annulation of MCPs via C−H/C−C activation annulation with ketimines to deliver polycyclic anilines (Scheme ) . The authors provided detailed mechanistic evidence for this a facile C−H metalation.…”