Efficient synthesis of 2-methyl derivatives of 1,1′-bi(2-naphthol) and 1,1′-bi(2-phenols)

Reaction of 1,1'-binaphthol and structurally related 1,1'-biphenols with sulfonylating reagents [RSO2Cl; R = 4-Tol, Ph] leads to clean, ultraselective monoderivatisation, shown crystallographically in one case (2-OH-2'-OTs-1,1'-binaphthyl). Reaction of the remaining 2-hydroxy function with either Tf2O or NfF [Nf = nonaflate, CF3(CF2)(3)SO2-] affords the protected/activated cores (2-(RO)-O-1-2'-(RO)-O-2-1,1'-biaryl) [R-1,R-2 pairs = Tf,Ts (X-ray); Tf,SO2Ph; Nf,Ts (on 1,1'-binaphthyl core); Tf,Ts; Nf,Ts (on 1,1'-biphenyl core); Tf,Ts; Nf,Ts (on 3,3',5,5'-tetramethyl-1,1'-biphenyl core)]. Reaction of the Tf,Ts species with either MeMgBr/NiCl2(dppe) (for the 1,1'-binaphthyl) or (AlMe3)(2)(DABCO)/Pd-2(dba)(3) (for the 1,1'-biphenyl) affords 2-OH-2'-Me-1,1'-biaryl units on subsequent hydrolysis (crystallographically characterised in the binaphthyl case). The latter methyl/hydroxy compounds are doubly deprotonated by either nBuLi/TMEDA or nBuLi/tBuOK to afford dianions that react cleanly with Cl2SiPh2 (two X-ray structures). The equivalent reaction of the 2-OH-2'-Me-1,1'-binaphthyl with Ph(O)Cl-2 is less clean due to the absence of a strong Thorpe-Ingold effect. ((c) Wiley-VCH Verlag GmbH & Co.