No abstract

The N -butyl amide group, CONHBu, has been found to be an effective promoter of the [1,2]-Wittig rearrangement of aryl benzyl ethers and thus allow the two-step synthesis of isomerically pure substituted diarylmethanols starting from simple hydroxybenzoic acid derivatives. The method is compatible with a wide range of functional groups including methyl, methoxy, and fluoro, although not with nitro and, unexpectedly, is applicable to meta as well as ortho and para isomeric series.

The behaviour of 14 ortho-functionalised 2-aryloxazolines (11 of them prepared and characterised for the first time) with butyllithium has been examined. Significant limitations to the Wittig rearrangement of such systems are revealed. In terms of asymmetric Wittig rearrangement, good diastereoselectivity is obtained with a valine-derived 4-isopropyl oxazoline, but this is compromised by racemisation upon hydrolysis. More encouraging selectivity is achieved in the Wittig rearrangement of an acyclic phenylalanine-derived ortho-benzyloxy benzamide.

A series of seven O-ethyl-N-butylphenylphosphonamidates with benzyl ether substituents at the para or meta position have been prepared and fully characterised. Upon treatment with n-butyllithium in THF at RT, these undergo Wittig rearrangement in six cases to give the novel phosphonamidate-substituted diarylmethanols in moderate to good yield.

Molecular structures of (R)-2,2'-dimethyl-1,1 '-binaphthyl [monoclinic, a = 11.24420 (11), b = 10.56190 (9), c = 13.27180 (13) Å, β = 90.7041 (9)°, space group P2 1 ] and (±)-2-bromomethyl-2'-dibromomethyl-1,1'-binaphthyl [triclinic, a = 9.4637 ( 14), b = 9.9721 ( 18), c = 9.9922 (19) Å, α = 100.093 (5), β = 97.141 (5), γ = 92.585 (4)°, space group P-1] are reported and compared with those of other simple 2,2'-disubstituted-1,1'-binaphthyls.