Silver acetate catalysed cycloadditions of isocyanoacetates

Silver acetate is an efficient catalyst for the cycloaddition of methyl isocyanoacetate with Michael-acceptors under mild conditions to give Delta(1)- or Delta(2)-pyrrolines in good yields. In the case of acrolein, novel chemoselectivity was observed. In the absence of a suitable olefin isocyanoacetates undergo silver acetate catalysed cyclodimerisation to give imidazoles in excellent yields. The mechanism of the cycloadditions has been probed. The reaction has been combined with azomethine ylide 1,3-dipolar cycloadditions in a one-pot sequential cascade process to afford the 7-azabicyclo[2.2.1]heptane ring system, a characteristic structural feature of the naturally occurring potent analgesic epibatidine. (C) 1999 Elsevier Science Ltd. All rights reserved.