A variety of 3-yne-1,2-diol derivatives 1, bearing a primary or secondary alcoholic group at C-1, have been efficiently converted into high value-added furan-3-carboxylic esters 2 in one step by PdI2/KI-catalyzed direct oxidative carbonylation, carried out in alcoholic media under relatively mild conditions (100 °C under 40 atm of a 4:1 mixture of CO-air). Carbonylated furans 2 were obtained in fair to excellent isolated yields (56-93%) through a sequential 5-endo-dig heterocyclization-alkoxycarbonylation-dehydration process, using only oxygen as the external oxidant. Under similar conditions, 2-methyl-3-yne-1,2-diols 3, bearing a tertiary alcoholic group, afforded 4-methylene-4,5-dihydrofuran-3-carboxylates 4 in satisfactory yields (58-70%).
Synthesis of furan-3-carboxylic and 4-methylene-4,5-dihydrofuran-3-carboxylic esters by direct palladium iodide catalyzed oxidative carbonylation of 3-yne-1,2-diol derivatives
GABRIELE, Bartolo;MANCUSO R;VELTRI, Lucia;
2012-01-01
Abstract
A variety of 3-yne-1,2-diol derivatives 1, bearing a primary or secondary alcoholic group at C-1, have been efficiently converted into high value-added furan-3-carboxylic esters 2 in one step by PdI2/KI-catalyzed direct oxidative carbonylation, carried out in alcoholic media under relatively mild conditions (100 °C under 40 atm of a 4:1 mixture of CO-air). Carbonylated furans 2 were obtained in fair to excellent isolated yields (56-93%) through a sequential 5-endo-dig heterocyclization-alkoxycarbonylation-dehydration process, using only oxygen as the external oxidant. Under similar conditions, 2-methyl-3-yne-1,2-diols 3, bearing a tertiary alcoholic group, afforded 4-methylene-4,5-dihydrofuran-3-carboxylates 4 in satisfactory yields (58-70%).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
