New activation methods used in green chemistry for the synthesis of high added value molecules

Abstract

In the chemical and pharmaceutical industry, molecular organic chemistry is undergoing a green revolution in order to avoid waste by developing a cleaner and safer chemistry. This change is subject to the new European regulation REACH. One of the major goals of organic synthesis is to design molecules with high added value by developing synthetic methods highly selective, economical and environmentally friendly. To satisfy the societal expectation new activation methods must be developed in order to shorten the synthesis, to respect the principle of atom economy and to substitute pollutants or toxic organic solvents. In this context, our group focuses its research on the synthesis of biologically active molecules, developing new environmentally friendly synthetic strategies and more energy-efficient alternatives such as microwaves, ultrasound, photochemistry or biotransformation. We present here how various activation methods used for the preparation of several high-value compounds can dramatically enhance yields and selectivity. First, we describe microwave-assisted syntheses of precursors of [11C] PIB, a tracer used in PET imaging and amides intermediates of natural products. We describe also the selective reduction of nitro compounds using ultrasound activation and a facile pathway to obtain β3-chiral aminoacids by biotransformation using purified nitrilases. Finally the results concerning the alkylation of α-aldehydes, using visible light and dyes as catalysts without transition metal are discussed. Some general considerations concerning the activation methods and their impact on the environment and the energy saving are given.