Prodn. of ester cpds. contg. carbamate gps. - by esterifying corresp. alcohol with acid anhydride using basic catalyst, useful in chemical and pharmaceutical industry

摘要

Prodn. of esters R1-COO-X-OCO-NH-R2 (IA) or R1-COO-X-NHCOO-R2 (IB) contg. carbamate gps. involves reacting an alcohol HO-X-OCONH-R2 (IIA) or HO-X-NHCOO-R2 (IIB) contg. carbamate gps. with an acid anhydride (R1-CO)2O (III) in the presence of basic catalysts (IV), thus R1= opt. substd. satd., or unsatd. 1-18C (cyclo)aliphatic, arylaliphatic or aromatic hydrocarbyl; R2= H or as R1; X= a divalent, opt. 1-12C aliphatic or aromatic gp. Reaction is carried out at 20-180, pref. 60-140, esp. 80-120 deg.C, using a (II)/(III) molar ratio of 1:5 to 5:1, pref. 1:3 to 3:1, esp. 1:1.5 to 1.5:1, pref. in the presence of solvents (pref. (cyclo)aliphatic or aromatic (halo)hydrocarbons, esters, ethers, glycol ether esters, amides, sulphones and/or sulphoxides). (IV) pref. are alkali metal hydroxides (NaOH, KOH), alkali metal alcoholates (MeONa, t-BuOK), tert. amines (Net3) or N-heterocyclic bases (pyridine, 4-(N,N-dimethylamino) -pyridine, 1,4-diazabicyclo (2.2.2)octane, 1,5-diazabicyclo(4.3.0) non-5-ene, 1,8-diazabicyclo(5.4.0) undec-7-ene or 2-ethyl-4 -methylimidazole. USE/ADVANTAGE - (I) are useful in the chemical and pharmaceutical industries. Reaction can be carried out in a wide temp. range and gives high yields, since reaction of acid anhydride gps. with carbamate gps. is eliminated or minimised.