Microwave assisted organic synthesis of amino-aldehydes precursors of bioactive compounds

BISCUSSI, BRUNELLA; ANA PAULA MURRAY

Rosario

Congreso; 4º Reunión Internacional de Ciencias Farmacéuticas; 2016

UNR

Amines are some of the most important bioactive compounds known. They work in living organisms as bioregulators, neurotransmitters, in defense mechanisms, etc. Because of their biological activities many natural amines are nowadays used as medicines and many others are used as source to prepare more active semisynthetic derivatives. Carbonyl group from aldehydes is a versatile functional group which can lead to alcohols, alkenes, carboxylic acids, imines, amines, etc. In the course of a multistep synthesis, we face the challenge of optimizing the synthesis of w-aminoalkyl-p-substituted benzaldehydes, intermediates required for the synthesis of other bioactive compounds. The traditional synthesis of these building-blocks requires prolonged heating (24 hours at 40°C) to achieve good yields (87-91%). In this work, we describe an optimized method to obtain p-(w-aminoalkyl)-benzaldehydes starting from the corresponding secondary amines and an halogenated precursor. The microwave-assisted synthesis of a group of aminoaldehydes (II) was carried out from brominated precursor (I) and five secondary amines by a nucleophilic substitution reaction (Scheme 1). The solvent chosen for the reactions was anhydrous dimethylformamide. A ratio 3:1 for the amine and the brominated compound was employed. The reactions were performed on a CEM Discover, varying the time and microwave power. The yield of the expected products in all cases exceeded the 87% and reaction times were optimized to 5 - 15 mins.