Transition Metal-catalyzed Reaction Of α-Diazo Carbonyl Compounds And Alkynes

Metal carbene has attracted a great attention because they can undergo diverse synthetically useful trasformations. Transition metal-catalyzed decomposition of diazo compounds is an important method to form metal carbene. We have extensively studied 1,2-migration reaction of Rh(II) carbene. Remarkable bystander effect has been observed. When theβsubstituted group is not an electron-withdrawing-group, 1,2-hydride shift is predominant, On the contrary, 1,2- aryl or alkenyl or alkynyl shift becomes predominant when there is an electron-withdrawing substituent in theβposition. In this paper, steric effect of bystander group was found to have important effect on the migratory aptitude. Whenβsubstituted group is trimethylsiloxy, a bulkier electron-donating-group, 1,2-phenyl shift becomes predominant. Increasing the bulkiness of the group connected to the carbonyl group, 1,2-hydrogen shift becomes predominant, even theβsubstituted group is an electron-withdrawing substituent. At the same time, kinetic isotope effect experiment was carried out to investigate the mechanism of 1,2-shift reaction via Rh(II) carbene. The results indicated significant isotope effect in 1,2-hydrogen shift of metal carbine.The effects of axial ligands of Rh(II)-carbenoid over the reaction was investigated. The reactivity and selectivity of Rh(II)-carbenoid can be affected through adding ligands. This shows a new method to design reaction via Rh(II)-carbenoid.Au-catalyzed reaction of alkynes has been investigated in order to generate metal carbene by an alternative pathway. In this investigation, we have developed a novel method to synthesize quinoline derivatives by AuCl3/CuBr-catalyzed three-component reaction of aldehyde, amine and alkyne. The mechanism of this reaction has been investigated through control experiments. Finally, condensation of EDA with aldehydes, catalyzed efficiently by DBU in water, was found to giveβ-hydroxy-α-diazo carbonyl compounds. The hydroxy group was converted to trimethylsiloxy group in high yields to giveβ-trimethylsiloxy-α-diazo carbonyl compounds. The Rh(II)-catalyzed reaction was controlled by steric effect of bystander group to proceed 1,2-aryl shift migration as the major pathway. Removal of TMS group by silica gel afforded the correspondingβ-hydroxy-α-aryl acrylates. A new decomposition pathway of diazo compound was observed in the reaction ofβ-trimethylsiloxy-α-diazo carbonyl compounds with TMSX (X = Cl, Br, I).