New Initiation Modes for Directed Carbonylative C–C Bond Activation: Rhodium-Catalyzed (3 + 1 + 2) Cycloadditions of Aminomethylcyclopropanes

Abstract

Under carbonylative conditions, neutral Rh(I)-systems modified with weak donor ligands (AsPh3 or 1,4-oxathiane) undergo N-Cbz, N-benzoyl, or N-Ts directed insertion into the proximal C–C bond of aminomethylcyclopropanes to generate rhodacyclopentanone intermediates. These are trapped by N-tethered alkenes to provide complex perhydroisoindoles.

Fused‐Ring Formation by an Intramolecular “Cut‐and‐Sew” Reaction between Cyclobutanones and Alkynes

“…Notably, similar bicyclic structures could also be obtained through [3+2+1] cycloaddition reactions involving C−C bond cleavage of cyclopropanes. The coupling of simple cyclopropanes, CO, and alkynes was first reported by Koga and Narasaka, albeit with low catalyst turnover and limited substrate scope (Scheme b).…”

“…[2g] In addition, decarbonylation of cyclobutanones to form the corresponding cyclopropane byproduct is always amajor competing pathway. [2a,g,h] As illustrated in Scheme 2a,d irect formation of rhodacycle A,t he reactive intermediate for subsequent 2p insertion, is more difficult than formation of rhodacycle B.O ne possible solution is to enable af acile and reversible decarbonylation and reinsertion pathway, [4] in which rhodacyclopentanone B can be initially converted to rhodacyclobutane intermediate C and then to rhodacycle A by CO reinsertion. We anticipated that the choice of ligand would be critical for this transformation;t he ligand should allow efficient decarbonylation and CO reinsertion without promoting further reductive elimination of C (an irreversible process to give cyclopropanes,s ee below,S cheme 5a), and represents the main difference from the prior benzocyclobutenone system.…”

“…Initially,c ontrol experiments showed that both the phosphine and Rh complex played pivotal roles in this reaction ( Table 1, entries 2a nd 3). Ar ange of monodentate phosphine ligands was found to be effective,a nd generally,h igher conversion was obtained with more electron-rich ligands ( Table 1, entries [4][5][6]. Surprisingly, one important factor was the ligand/metal ratio,w ith 1.6:1 being optimal (for detailed optimization, see the Supporting Information).…”

Efficient Preparation of 2,3-Disubstituted Cyclopropane-1-Carbonitriles via Selective Decarboxylation of 1-Cyanocyclopropane-1-Carboxylates

“…In addition, as one of the most important strained cyclic compounds, substituted cyclopropanes have exhibited versatile applications in organic synthesis as synthetic intermediates. [10][11][12] Cyclopropane derivatives are usually obtained through traditional approaches, including the Simmons-Smith cyclopropanation reaction, which is one of the most important methods for the preparation of substituted cyclopropanes from alkenes, 13 the Corey-Chaykovsky cyclopropanation reaction, 14,15 the metal-catalysed reaction of a diazo compound with alkenes and the cyclisation reaction of carbenes with alkenes.Although classical and well-established methods have proven to be very effective for the synthesis of cyclopropane derivatives, efficient synthesis of polysubstituted cyclopropanes with flexible substituent patterns has long been a challenging goal. Recently, some studies have reported that various improved ylide-mediated cyclisations, such as a semi-stabilised sulfur, nitrogen, selenium or arsenic ylide reacting with an alkene afford to a 1,2,3-substituted cyclopropane core.…”

“…In addition, as one of the most important strained cyclic compounds, substituted cyclopropanes have exhibited versatile applications in organic synthesis as synthetic intermediates. [10][11][12] Cyclopropane derivatives are usually obtained through traditional approaches, including the Simmons-Smith cyclopropanation reaction, which is one of the most important methods for the preparation of substituted cyclopropanes from alkenes, 13 the Corey-Chaykovsky cyclopropanation reaction, 14,15 the metal-catalysed reaction of a diazo compound with alkenes and the cyclisation reaction of carbenes with alkenes.…”