Silver acetate catalysed cycloadditions of isocyanoacetates

Silver acetate is an efficient catalyst for the cycloaddition of methyl iso cyanoacetate with Michael-acceptors under mild conditions to give Delta(1)- or Delta(2)-pyrrolines in good yields. In the case of acrolein, novel chem oselectivity was observed. In the absence of a suitable olefin isocyanoacet ates undergo silver acetate catalysed cyclodimerisation to give imidazoles in excellent yields. The mechanism of the cycloadditions has been probed. T he reaction has been combined with azomethine ylide 1,3-dipolar cycloadditi ons 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.