Palladium-catalyzed Intramolecular Asymmetric Heck Reaction Of Pyrrole

By using strategy of palladium-catalyzed intramolecular asymmetric Heck reaction,the fused ring structure and the spiro ring structure containing the quaternary carbon chiral center can be efficiently and quickly constructed.Based on the intramolecular asymmetric Heck reaction,the asymmetric Heck reaction and the asymmetric Heck spirocyclization reaction of pyrrole were realized respectively in this paper.A series of dihydropyrrole compounds of fused ring and spiro ring structure containing quaternary carbon chiral center were constructed.Using N-?2-bromobenzoyl?-substituted 2,5-dimethylpyrrole as a substrate,successfully achieved the dearomatization progress of pyrrole,a dihydropyrrole compound with a fused ring structure was constructed.After screening the chiral ligand,solvent and base,under the condition of Pd?dba?₂ as the catalyst,?S?-SEGPHOS as the chiral ligand,Et₃N as the base,DMF and NMP as a mixed solvent,at 100 ^oC,the reaction was performed in excellent enantioselectivities?87-95%?that synthesized a series of fused ring dihydropyrroles containing quaternary carbon chiral centers,and most of substrates can achieve reaction in moderate to good yields.Using C2-?2-bromobenzoyl?-substituted 3-methylpyrrole as a substrate and the same strategy of intramolecular asymmetric Heck reaction,then got through the progress of?-H elimination,a dihydropyrrole compound of spiro ring structure was constructed by dearomatization progress.After screening the solvent,under the condition of Pd?dba?₂ as the catalyst,L7 as the chiral ligand,Et₃N as the base,DMF as the solvent,at 100 ^oC,the reaction was performed in moderate yields?41-67%?and excellent enantioselectivities?81-94%?that synthesized a series of spiro ring dihydropyrroles containing quarternary carbon chiral centers by using N-Ts-C2-acyl-pyrrole as substrate.