Catalytic utility of a bimetallic (pincer) PNN-based nickel complex in the synthesis of quinolines and α-alkylation of ketones†

Abstract

Here, we report the synthesis and characterization of a bipincer nickel complex containing bipyridine-based bisphosphine and its catalytic application in quinoline synthesis and α-alkylation of ketones. The reaction of [2,2′-{C₅H₃N-3-N(H)C(O)C₆H₄PPh₂-o}₂] (1) with [NiCl₂(DME)] afforded bipincer complex [{NiCl)(2,2′-C₅H₃N-3-N(H)C(O)C₆H₄PPh₂-o)}-κ³-P,N,N]₂ (2). Complex 2 catalysed efficiently the synthesis of quinoline derivatives via acceptor-less dehydrogenative coupling of 2-aminobenzyl alcohol and ketones or secondary alcohols, and also α-alkylation of ketones with alcohols with a very low catalyst loading (0.5 mol%) at 110 °C.