Reaction of 2,4-Difunctional Esters of 5-tert-Butylfuran-3-carboxylic Acid with Nucleophilic Reagents

Ethyl 5-tert-butyl-4-(chloromethyl)-2-methylfuran-3-carboxylate was brominated with N-bromo-succinimide to obtain the corresponding 2-bromomethyl derivative. The latter is selectively phosphorylatedwith trimethyl, triethyl phosphites by the bromomethyl group. The resulting 4-(chloromethyl)furyl]methyl-phosphonates in the presence of secondary amines and sodium butanethiolate behave as alkylating agents,while sodium phenolate causes their decomposition. 4-Acetoxymethyl- and 4-phenoxymethyl derivatives of the starting product are also selectively brominated with N-bromosuccinimide by the 2-methyl group. The first of the 2-(bromomethyl)furans formed is smoothly phosphorylated with trimethyl phosphite, while the second one under the action of triethyl phosphite gives a mixture of phosphorylation and debromination products. In all the cases, an additional electron-acceptor group in position 4 of alkyl 2-(bromomethyl)-5-tert-butylfuran-3-carboxylate considerably accelerates the Arbuzov reaction.