Variability of Rhodium(III)-Catalyzed Reactions of Aromatic Oximes with Alkenes

This work is dedicated to the memory of Prof. Keith Fagnou, who made a seminal contribution to rhodium(III)-catalyzed C−H functionalization reactions, and sadly passed away ten years ago at the age of 38.

Abstract

Acetophenone oxime reacts with various alkenes in the presence of the rhodium catalyst [Cp*RhCl₂]₂ (2.5 mol%; Cp* = pentamethylcyclopentadienyl) and 1,1,1,3,3,3-hexafluoropropan-2-ol as an important cosolvent. Styrene, aliphatic terminal alkenes, and strained cyclic alkenes gave the corresponding substituted dihydroisoquinolines in yields of 50–99%. On the other hand, alkenes containing functional groups close to the double bond gave a variety of different products. The reactions of acetophenone oxime with styrene or dec-1-ene in the presence of the chiral catalyst [(C₅H₂ ^t Bu₂CH₂ ^t Bu)RhI₂]₂ provided the corresponding dihydroisoquinolines with improved regioselectivity but a low enantiomeric ratio (61:39 in both cases).

Key words

C–H activation - rhodium catalysis - oximes - alkenes - isoquinolines

• References and Notes

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