192195-13-4Relevant academic research and scientific papers
Anomalous intramolecular C-H insertion reactions of rhodium carbenoids: Factors influencing the reaction course and mechanistic implications
Clark, J. Stephen,Dossetter, Alexander G.,Wong, Yung-Sing,Townsend, Robert J.,Whittingham, William G.,Russell, C. Adam
, p. 3886 - 3898 (2007/10/03)
The intramolecular insertion of rhodium carbenoids into the α-C-H bonds of allylic ethers to give 3(2H)-furanones has been explored. Cyclopropanation is favored irrespective of the complex used for carbenoid generation or the substitution pattern of the allylic ether, unless a substituent is placed on the tether connecting the ether to the α-diazo ketone. Unusual acetal products resulting from an anomalous C-H insertion process are obtained in addition to the expected 3(2H)-furanones formed by conventional carbenoid C-H insertion. These acetals are the favored C-H insertion products in certain circumstances and particularly in cases where carbenoid generation is effected using an electron-deficient rhodium complex. Experiments with simple deuterium labeled substrates reveal that anomalous C-H insertion products arise by a mechanism that is distinct from that leading to the formation of conventional C-H insertion products. The formation of acetal products and the outcome of reactions performed using deuterium-labeled substrates suggest that a mechanism involving hydride migration to the rhodium center of the carbenoid is operative.
