Heterocyclic synthesis with nitriles: synthesis of some novel furo [2,3-b] nicotinic acid derivatives of anticipated biological activity

ABSTRACT

2-Amino-5-phenylfuran-3-carbonitrile 2 reacts with malonic acid derivatives 3a-d and 6 to afford the furo [2, 3-b] pyridine derivatives 5a-c. Compounds 2 reacts with urea and thiourea to afford the pyrrole derivative 10 which was also obtained from 2 and ammonium acetate. The reaction of 2 with the arylidene derivatives 11a-f yield the furo [2, 3-b] nicotinonitrile derivatives 13a, c, e; which were hydrolyzed to the nicotinic acid derivatives 14a, c, e, respectively. Compound 2 reacts also with the acrylic acid derivatively 15a-c to afford the furo [2, 3-b] nicotinic acid derivatives 17a-c, which were hydrolyzed to give the furo [2, 3-b] nicotinic acid 18. Compounds 5b, c undergo S-or N-alkylation on reaction with phenacyl bromide 19a and ethyl bromoacetate 19b to yield compounds 20a-d, respectively. Compound 5b reacts with hydrazine hydrate to afford the hydrazino derivative 22 which could be cyclized into the furopyridopyrazole derivative 23. Compound 5b reacts also with I2/Kl in DMF to afford the disulphide 24