Rhodium-Catalyzed Direct Addition of Aryl C-H Bonds to N-Sulfonyl Aldimines

摘要

Nucleophilic addition of highly reactive aryl Grignard reagents and other related organometallic reagents to car-bonyl compounds and their derivatives is a fundamental and important reaction for the construction of O-C bonds. This approach has been well developed (since early last century) and broadly utilized to synthesize alcohol and amine compounds. Traditionally, the requirement of organohalides as the starting materials to produce the active organometallic reagents causes environmental problems owing to their tedious and sluggish preparation (Scheme l). As a valuable complementary method, directed ortho metelation (DoM) of functionalized arene compounds has its advantages from a synthetic point of view. Apart from their tedious preparation, both Grignard and DoM approached involve themanipulation of air-and moisture-sensitive reagents and the generation of unwanted salt waste. Recent Friedel-Crafts-type direct alkylation of electron-rich arene compounds have been developed. This reaction is catalyzed by a Lewis/ Br0nsted acid, however, a limited substrate scope and difficulty in regioselective control were encountered. In comparison, transition metal complexes provide a broader outlook for the development of new transformations that may provide tunable reactivity and selectivity. The transition-metal-catalyzed addition of C-H bonds to alkene and alkyne derivatives have been extensively investigated. Meanwhile, significant contributions have been made to the field by the addition of C-H bonds to carbonyl compounds and their derivatives, despite the demand for special additives or limited substrate scope. Herein we demonstrated an "ideal" addition of "inert" aryl C-H bonds to C=N groups in the absence of any additives and without any undesirable waste under mild and neutral reaction conditions.