Catalytic asymmetric allylic and benzylic carbon-hydrogen bond insertion induced by rhodium carbenoids

The primary objective of this thesis was the exploration of dirhodium tetrakis[(S)-(N-dodecylbenzenesulfonyl)prolinate] (Rh2(S-DOSP)4) catalyzed allylic and benzylic C-H bond insertion. The first area investigated was the allylic C-H insertion involving the carbenoid derived from Rh2(S-DOSP) 4 decomposition of aryldiazoacetates. The reaction was highly regioselective and enantioslective. Allylic C-H insertion using carbenoids derived from the vinyldiazoacetates was found to form C-H insertion/Cope rearrangement products in excellent ee (99%) and de (>98%) through a combined C-H insertion/Cope rearrangement mechanism. This process provided a new strategy for construction of a quaternary chiral center by a catalytic method. This reaction was further extended to 1,2-dihydronaphthalene systems and the clean C-H insertion product was formed with excellent yield and stereoselectivity through a combined C-H insertion/Cope rearrangement followed by a Cope rearrangement sequence. When the allylic position is sterically hindered, the C-H insertion cleanly occurs at benzylic positions with very high diastereoselectivity and enantioselectivty. A double C-H insertion into 1,2-dihydronaphthalenes was also described.;The second area investigated was the benzylic C-H insertion. First, the benzylic methylene C-H insertion into various p-substituted ethylbenzene derivatives was carried out. A Hammett study was also conducted and the results indicated that significant positive charge was involved in the transition state. Benzylic methyl C-H insertion was also a feasible reaction if the benzene ring was sterically protected from the attack of the carbenoid. The concise syntheses of two natural products, (+)-imperanene and (-)-alpha-conidendrin, were also completed using benzylic methyl C-H insertion as the key step. A new Lewis acid promoted rearrangement-nucleophitic substitution reaction was also discovered in the course of study towards the synthesis of (-)-podophyllotoxin analogs.;The third area investigated was the methyl C-H insertion alpha to nitrogen. By using excess of the carbenoid processor, a double C-H insertion into N,N-dimethylanilines afforded C2-symmetric anilines with very high level of asymmetric induction.;The final part of the work was the miscellaneous part which includes deactivation effect of an acetyl protecting group in C-H insertion and the cross coupling reactions of diazo compounds.