title: Practical enantioselective arylation and heteroarylation of aldehydes with in situ prepared organotitanium reagents catalyzed by 3-aryl-H8-BINOL-derived titanium complexes.
abstract: A highly efficient and practical method for the catalytic enantioselective arylation and heteroarylation of aldehydes with organotitanium reagents, prepared in situ by the reaction of aryl- and heteroaryllithium reagents with ClTi(OiPr)3, is described. Titanium complexes derived from DPP-H8 -BINOL (3d; DPP=3,5-diphenylphenyl) and DTBP-H8 -BINOL (3e; DTBP=3,5-di-tert-butylphenyl) exhibit excellent catalytic activity in terms of enantioselectivity and turnover efficiency for the transformation, providing diaryl-, aryl heteroaryl-, and diheteroarylmethanol derivatives in high enantioselectivity at low catalyst loading (0.2-2 mol%). The reaction begins with a variety of aryl and heteroaryl bromides through their conversion into organolithium intermediates by Br/Li exchange with nBuLi, thus providing straightforward access to a range of enantioenriched alcohols from commercially available starting materials. Various 2-thienylmethanols can be synthesized enantioselectively by using commercially available 2-thienyllithium in THF. The reaction can be carried out on a 10 mmol scale at 0.5 mol% catalyst loading, demonstrating its preparative utility.
authors: Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Matsugasaki, Kyoto 606-8585, Japan.
authors: Ami
authors: A
authors: Uenishi
authors: Yuya
authors: Y
authors: Nakagawa
authors: Hironobu
authors: H
authors: Osumi
authors: Toshiro
authors: T
authors: Harada
mesh_terms: D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D006842:Hydrocarbons, Brominated / Q000737:chemistry; D007202:Indicators and Reagents; D015394:Molecular Structure; D009284:Naphthols / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D014025:Titanium / Q000737:chemistry*
chemical_list: D000438:Alcohols; D000447:Aldehydes; C406944:BINOL, naphthol; D006842:Hydrocarbons, Brominated; D007202:Indicators and Reagents; D009284:Naphthols; D009942:Organometallic Compounds; D014025:Titanium