DMSO-SbCl₅ (1 : 1) 錯体と対称型ジメチルベンゾピナコールとの反応

抄録

Reactions of symmetrically dimethylsubstituted benzopinacols and 1, 2-dipheny1-1, 2-bis (ρ-chloro-phenyl) -1, 2-ethanediol (5) with the DMSO-SbC15 (1 : 1) complex (Sb complex), afforded two Pinacol rearrengment products, ([A] and [B]), were obtained in the case of except for the reaction of 1, 2-diphenyl-1, 2-di-m-toly1-1, 2-ethanediol (3) in nitroethane.
X-C₆H₄-C-H₅C₆-HO-C-C₆H₅-OH-C₆H₄-X→X-C₆H₄-C-C₆H₅-C₆H₅-C=O-C₆H₄-X+C₆H₅-C-X-C₆H₄-X-C₆H₄-C=O-C₆H₄ [A] [B]
X : o-Me (2), m-Me (3), p-Me (4), p-Cl (5)
Higher product ratios ([B] / [A]) were achieved in the Pinacol rearrangement of (3) and 1, 2-dipheny1-1, 2-di-p-toly1-1, 2-ethanediol (4) with the Sb complex in nitroethane, compared to ([B] / [A]) using benzene as the solvent. ([B] / [A]), values were lower in the reaction of 1, 2-diphenyl-1, 2-di-o-tolyl-1, 2-ethanediol (2) and (5) with the Sb complex in nitroethane. ([B] / [A]) in the Pinacol rearrangement of these benzopinacols in nitroethane were essentially the same as those for the Pinacol rearrrangement using iodine-acetic acid.
The Pinacol rearrangement of benzopinacols with the Sb complex appeared to proceed via an intramolecular pathway.