A new multicomponent reaction catalyzed by a [Lewis Acid](+)[Co(CO)(4)](-) catalyst: stereospecific synthesis of 1,3-oxazinane-2,4-diones from epoxides, isocyanates, and CO.
The use of mechanistic information to develop a new, catalytic multicomponent reaction is described. The complex [(salph)Al(THF)2]+[Co(CO)4]- (1, salph = N,N'-o-phenylenebis(3,5-di-tert-butylsalicylideneimine), THF = tetrahydrofuran), which is known to carbonylate epoxides, aziridines, and beta-lactones, was used to catalyze the synthesis of 1,3-oxazinane-2,4-diones from epoxides, isocyanates, and CO. Under optimized conditions, the reaction was both selective and high-yielding. 1,3-Oxazinane-2,4-diones were synthesized from a variety of epoxides and isocyanates, including some epoxides that do not undergo simple ring-expansion carbonylation. The best results were obtained using highly electrophilic isocyanates. The mechanism of the multicomponent reaction was investigated using labeling and stereochemistry, and the data obtained were consistent with the 1-catalyzed formation of beta-lactone and 1,3-oxazinane-2,4-dione from a common intermediate.
Church
Tamara L
TL
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA.
Byrne
Christopher M
CM
Lobkovsky
Emil B
EB
Coates
Geoffrey W
GW