Synthesis and characterization of six-membered pincer nickelacycles and application in alkylation of benzothiazole

Abstract

Six-membered pincer nickelacycle complexes have been synthesized and employed for the catalytic C–H bond alkylation of benzothiazole. The pincer nickelacycle, {κP, κC, κP- (2 - iPr 2POCH 2-C 6H 3- 6 -CH 2OP iPr 2)} NiBr , [(iPr4-POCCCOP)NiBr(2)] was synthesized by the reaction of 1,3 - iPr 2POCH 2-C 6H 4-CH 2OP iPr 2[(iPr4-POCCCOP)-H(1)] with (CH3CN)2NiBr2 in the presence of Et 3N via the C(2)–H activation on ligand 1. Treatment of [(iPr4-POCCCOP)NiBr](2) with AgOAc afforded the complex [(iPr 4-POCCCOP) Ni (OAc)] (3) in good yield. Both the complexes 2 and 3 were characterized by 1H , 13C and 31P -NMR spectral analysis. Further, the molecular structures of complexes 2 and 3 were established by X-ray crystallography. The complex 2 was found to be an active catalyst for the C–H bond alkylation of benzothiazole with alkyl halides containing β–hydrogen atoms. Graphical abstract: Synopsis. Six-membered pincer nickelacycles have been synthesized and structurally characterized, which show catalytic activity for the C–H bond alkylation of benzothiazole with alkyl halides containing β–hydrogen atoms.[Figure not available: see fulltext.].