The reactions of propargyl alcohols withcarbon dioxide in supercritical carbon dioxide or inacetonitrile with gaseous carbon dioxide in the presenceof organic bases as catalysts have been examined.Bicyclic guanidines are effective catalysts forthe formation of a-methylene cyclic carbonatesunder mild reaction conditions. Oxoalkyl carbonates,oxoalkyl carbamates or a-methyleneoxazolidinonesare obtained in high yields and good selectivities inone-step starting from propargyl alcohols and an externalnucleophile (alcohols or amines) using bicyclicguanidines as catalysts in supercritical carbon dioxide.Propargylic diols under the same reaction conditionsunderwent a rearrangement process instead ofcarbon dioxide insertion whereas in the presence ofan external nucleophile the formation of oxocarbonates,oxocarbamates or cyclic carbamates wasachieved in satisfactory yields.
Effective Guanidine-Catalyzed Synthesis of Carbonate and Carbamate Derivatives from Propargyl Alcohols in Supercritical Carbon Dioxide
GABRIELE, Bartolo;VELTRI, Lucia;
2011-01-01
Abstract
The reactions of propargyl alcohols withcarbon dioxide in supercritical carbon dioxide or inacetonitrile with gaseous carbon dioxide in the presenceof organic bases as catalysts have been examined.Bicyclic guanidines are effective catalysts forthe formation of a-methylene cyclic carbonatesunder mild reaction conditions. Oxoalkyl carbonates,oxoalkyl carbamates or a-methyleneoxazolidinonesare obtained in high yields and good selectivities inone-step starting from propargyl alcohols and an externalnucleophile (alcohols or amines) using bicyclicguanidines as catalysts in supercritical carbon dioxide.Propargylic diols under the same reaction conditionsunderwent a rearrangement process instead ofcarbon dioxide insertion whereas in the presence ofan external nucleophile the formation of oxocarbonates,oxocarbamates or cyclic carbamates wasachieved in satisfactory yields.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.