169057-75-4Relevant academic research and scientific papers
Asymmetric synthesis of axially chiral biaryls by nickel-catalyzed Grignard cross-coupling of dibenzothiophenes
Cho, Yong-Hwan,Kina, Asato,Shimada, Toyoshi,Hayashi, Tamio
, p. 3811 - 3823 (2004)
Catalytic asymmetric Grignard cross-coupling of 1,9-disubstituted dibenzothiophenes (6a-c) and dinaphthothiophene (6d) with aryl- and alkyl-Grignard reagents (7) proceeded with high enantioselectivity (up to 95% ee) in the presence of a nickel catalyst (3-6 mol %) coordinated with 2-diphenylphosphino-1,1′-binaphthyl (H-MOP) or oxazoline-phosphine ligand (i-Pr-phox) in THF to give 2-mercapto-2′-substituted-1,1′-biphenyls (8a-c) and 2-mercapto-2′-substituted-1,1′-binaphthyls (8d) in high yields. The mercapto group in the axially chiral cross-coupling products was converted into several functional groups by way of the methylsulfinyl group. The rate of flipping in dinaphthothiophene was measured by variable-temperature 31P NMR analysis of methyl-phenylphosphinyldinaphthothiophene derivative (21).
