Microwave assisted green synthesis of α, ά- bis (substituted- benzylidene) alkanones

Microwave assisted green synthesis of α, ά- bis (substituted- benzylidene) alkanones by the crossed- aldol condensation reaction of substituted aryl aldehydes with ketones in the presence of catalytic amount of NbCl5 in good to excellent yields. This reaction is carried out under solvent-free conditions. The results showed that aldehydes bearing electron–donating substituent's on phenyl-ring favored the formation of product in good to excellent yields with reaction times ranging between 3 and 7 min. In addition, furfural, cinamaldehyde, thiophene-2-carbaldehyde and 5-methylthiophene-2-carbaldehyde were investigated in aldol reaction, and the results showed excellent yields. Also, the reactions were carried out at room & thermal (80 0C) conditions. The results showed that the yields are in accordance with the microwave irradiations, But the time is 1.5-5 h at room temperature and 15-45 min in thermal conditions.