Synthesis of planar chiral ferrocenes via a Pd(0)-catalyzed syn-carbopalladation/asymmetric C–H alkenylation process

Abstract

The Pd(0)-catalyzed tandem intermolecular syn-carbopalladation/asymmetric C–H alkenylation reaction of N-ferrocenyl propiolamides with aryl iodides has been realized, generating planar chiral ferrocene[1,2-d] pyrrolinones in good yields.

Chiral Catalysts for Pd0‐Catalyzed Enantioselective C−H Activation

“…[38] In as imilar vein, Liu and co-workers recently reportedadomino syn-carbopalladation/CÀHa lkenylation reaction for the synthesis of fused pyrrolidinone-ferrocenes 18 with planar chirality (Scheme 9). [39] This reaction was enabled by ligand L 7 ,amember of the BINOL-derived MonoPhos-family of phosphoramidites. [40] As in the previouse xample (see Scheme 8), flanking substituents at the 3,3'-positions of the BINOL scaffold werec rucial for the enantioinduction, and unsubstituted scaffolds afforded low enantioselectivities.T he developedp rotocol tolerated an umber of substituents on the aryl moiety connectedt ot he triple bond, as well as on the aryl halide coupling partner.…”

Transition Metal‐Catalyzed Desymmetrizations Based on CH Activation Processes

“…The authors explored this concept to develop a method for the synthesis of enantioenriched pyridoferrocenes from ferrocenyl isocyanide derivatives and aryl iodides or bromides by Pd-catalyzed domino isocyanide insertion/ enantioselective C --H cyclization processes (Scheme 40) [122]. In a similar approach, Liu and coworkers developed a protocol for the preparation of planar chiral ferrocene [1,2-d] pyrrolidones via Pd-catalyzed alkyne insertion/enantioselective C --H cyclization of ferrocenyl scaffolds bearing internal alkyne pendants (Scheme 40) [123].…”

Stereoselective Synthesis of Azacycles Induced by Group 8–11 Late Transition Metals

“…The The Liu group has elaborated a successful method for the synthesis of planar chiral ferrocene[1,2-d] pyrrolinones by a tandem intermolecular transformation of N-ferrocenyl propiolamides with iodoarenes. [37] Products using phosphoramidite ligand 28 involving syn-carbopalladation and asymmetric CÀ H alkenylation were isolated in medium to high yields with high enantioselectivities (Scheme 30). Lower enantioselectivities were found with larger R 1 protecting groups (Et 77 %, Bn 74 % vs Me 91 %).…”