Metal catalyst and hydrogen gas free approaches for selective reduction of aldehyde to methyl group of different substituted furans

A process for the preparation of a 5-methyl substituted furan of general formula (I):

• where:
• R1 is selected from the group consisting of hydrogen, hydroxymethyl, alkyl, hydroxy, aldehyde, halide, ester, carboxyl, nitro, amino, amide, substituted amino, alkoxy/ether linkages, sulfur derivatives, phosphorous derivatives, aryl, and heteroaryl;
• and
• R2 and R3 are selected from the group consisting of hydrogen, alkyl, and aryl, the process comprising:
• (i) reacting an amine compound and an inorganic base with a substituted furfural in an alcoholic organic solvent selected from alkyl alcohols or cyclic alkyl alcohols at a reaction temperature from 120° C. to 140° C. for a reaction time period from 2 hours to 6 hours to obtain an in situ generated corresponding imine compound, the substituted furfural having formula (II):
• where R1, R2, and R3 of formula (II) are as defined in general formula (I);
• (ii) reducing the in situ generated corresponding imine compound of (i) under basic conditions in the alcoholic organic solvent to obtain a 5-methyl substituted furan of general formula (I);
• (iii) isolating the 5-methyl substituted furan;
• and
• (iv) optionally, purifying the isolated 5-methyl substituted furan.