Chiral porphyrin complexes of cobalt(II) and ruthenium(II) in catalytic cyclopropanation and amination reactions

The ligand influence in stereoselective carbene transfer reactions promoted by chiral metal porphyrin catalysts

“…The observed stereo-control, due to the chiral ligand skeleton, was only in part modified by the nature of the porphyrin core which was more responsible for the reaction chemoselectivity. In fact, when other 49 It should be noted that, even if the reaction always occurred with modest to poor stereoselectivities, (Scheme 20) cobalt(II) catalyst 109 promoted a cis-diastereoselectivity conversely to that which was reported for Halterman-type-catalysed cyclopropanations discussed to date.…”

Cyclopropanation Reactions Mediated by Group 9 Metal Porphyrin Complexes

“…To study the steric and conformational ligand requirements to obtain stereocontrol of the reaction, several years ago we synthesised the cobalt(II) complex [84] 19 (Figure 8) of the chiroporphyrin already reported by Marchon et al [85] The cyclopropanation of α-methylstyrene by EDA catalysed by 19 afforded the corresponding cyclopropanes with low diastereo-and enantioselectivity. The observed experimental results were justified by theoretical calculations, which disclosed the existence of 19 as a pool of interconverting atropisomers.…”

Co(porphyrin)-catalysed amination of 1,2-dihydronaphthalene derivatives by aryl azides

“…Large amounts of polymeric material was observed due to the well known tendency of indene to polymerise by radical coupling reactions [36] (Scheme 10). The lack of formation of 2,3-dihydro-N-(4-nitrophenyl)-1H-inden-1-amine (18) confirmed that cobalt porphyrins are not competent catalysts for the direct CeH amination of a-substituted cyclic styrenes. Thus, when a hydrogen atom abstraction is impossible the uncatalysed reaction is the only achievable process [34].…”