Title: Synthesis and Character of New Bis- (isoxazoline) Ligands
Abstract:Synthesis of two kinds of new bis(isoxazoline) ligand, achira 2,2'bis(isoxazolinyl)propane and (R)-2,2'-bis(isoxazolinyl)-1,1'-binaphthyl bearing an axial chirality is described.Both of the bis(isoxaz...Synthesis of two kinds of new bis(isoxazoline) ligand, achira 2,2'bis(isoxazolinyl)propane and (R)-2,2'-bis(isoxazolinyl)-1,1'-binaphthyl bearing an axial chirality is described.Both of the bis(isoxazoline) ligands accelerated the Pd(II)-catalyzed Wacker-type cyclization of alkenyl alcohol.The isoxazoline ligands were found to be essential to promote the cyclization.For the enantioselective reactions promoted by transition metal catalysts, effective optically active ligands are required to achieve high catalyst activity and high stereoselectivity. 1 We have previously reported the novel spiro bis(isoxazoline) ligands (SPRIXs), which have a chiral spiro backbone and isoxazoline units, and succeeded to demonstrate the first example of the use of an isoxazoline ligand for a transition metal-catalyzed asymmetric reaction.2a In view of the good affinity of SPRIXs to Pd(II) salts and the stability of SPRIXs under oxidative conditions, we developed a new asymmetric Wacker-type cyclization of alkenyl alcohols promoted by a Pd-SPRIX catalyst (Scheme 1).2b It is remarkable that these cyclizations are not promoted † This paper is dedicated to Professor Yuichi Kanaoka on the occasion of his seventy fifth birthday.Read More