C-C Bond Cleavage of 8-Quinolinyl Alkyl Ketone by ￥ò,￥?3-Allyl Rhodium(￥2) Complex

摘要

Bis(ethylene)rhodium(グ) chloride dimer reacted with vinylcyclopropane to give ヲ,ョ 3-allylrhodium(ゲ) complex 3. Complex 3 underwent C-C bond cleavage of 8-quinolinyl ethyl ketone 11, to form ョ3-1,3-dimethylallylrhodium(ゲ) complex 8, which was reductively eliminated by trimethyl phosphite to give 8-quinolinyl-1-methylbut-2-enyl ketone (10). More sterically hindered 8-quinolinyl alkyl ketones were allowed to react with complex 3 to afford corresponding alkenes as well as a mixture of complex 8 and ョ3-1-ethylallyl rhodium(ゲ) complex 19, identified as 10 and 8-quinolinyl-pent-2-enyl ketone (20) after reductive elimination. 8-Quinolinyl alkyl ketone bearing a sterically hindered alkyl group showed less reactivity for C-C bond cleavage and higher 20/10 ratio compared with those having a less sterically hindered alkyl group, such as 8-quinolinyl ethyl ketone (11).