Radical carbonylation/reductive cyclization for the construction of tetrahydrofuran-3-ones and pyrrolidin-3-ones.
Beta-hydroxyalkyl aryl chalcogenides obtained by regioselective ring-opening of epoxides with benzeneselenolate or -tellurolate were found to undergo efficient hetero-Michael addition when treated with ethyl propiolate. Subsequent carbonylation/reductive cyclization of the resulting vinylogous carbonates in the presence of AIBN/TTMSS and carbon monoxide (80 atm) afforded 2,5-disubstituted tetrahydrofuran-3-ones, predominantly as cis isomers (cis/trans = 4/1-9/1). Starting from a polymer-supported diaryl diselenide, the methodology was also successfully extended to solid-phase synthesis. Vinylogous carbamates prepared by hetero-Michael addition of aziridines to electron-deficient alkynes were regioselectively ring-opened with benzeneselenolate from the sterically least hindered side. Radical carbonylation/reductive cyclization of the resulting N-vinyl-beta-amino-alkyl phenyl selenides afforded 2,5-disubstituted pyrrolidin-3-ones, predominantly as cis isomers (cis/trans = 3/1-12/1).
Berlin
Stefan
S
Uppsala University, Institute of Chemistry, Department of Organic Chemistry, Box 599, SE-751 24, Uppsala, Sweden.
Ericsson
Cecilia
C
Engman
Lars
L