Expanding the scope of Et3B/O2-mediated coupling reactions of O,Te-acetal

Et3B/O2-mediated radical coupling reactions of O,Te-acetal 2 were explored using diverse electrophilic double bonds. Ethyl radical derived from Et3B under air cleaved the C–Te bond of 2 to generate α-alkoxy bridgehead radical I, which reacted with cycloalkenones, cycloalkylidenemalononitriles, allyl halides, and imines at or below ambient temperature. These intermolecular reactions from O,Te-acetal 2 were mild and versatile, and were superior to those of O,Se-acetal 1 in terms of efficiency and substrate scope. A total of 14 new and nine improved coupling reactions are described, all of which realized the installation of the functionalized carbon units at the sterically hindered bridgehead position of trioxaadamantane.

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