Aldehydes continued arylation reactions

Introduction of heteroatoms, e. g. N, S, or O, into hydrocarbon molecules adds substantial value, and new routes for such reactions are of continuous interest to the chemical industry. The two main classes of aromatic N-containing hydrocarbons are the arylamines and the aromatic N-heterocyclic compounds. The aryl-amines, which are required industrially, are manufactured by nitration of aromatics to nitroaromatics, followed by hydrogenation to arylamines [1,2]. Because of the lower demand for aromatic heterocycles than for arylamines, coal tar is still an important source of pyridine and methylpyridines (picolines). Increasing demand for aromatic heterocyclic compounds has led to processes in which aldehydes and ketones are condensed with NH3 to furnish pyridine and alkylated pyridines [3,4]. 

To a solution of potassium ferf-butoxide (0.05 mmol 5 mol%) in tert- mty alcohol (1 mL) in a test tube, a mixture of acetophenone (1 1.0 mmol) and aldehyde (2 1.0 mmol) was added followed by continuous stirring for several minutes at room temperature until the starting materials were completely disappeared (monitored by TLC) thiol (3 1.2 mmol) was then added to the reaction mixture, and was stirred to completion of the reaction. The solvent was evaporated, and chloroform (1 mL) was added and the crude product was subjected to preparative TLC (silica gel, eluent petroleum ether/Et20 = 7 4) to afford a pure p-aryl-p-mercapto ketone 4 in excellent yield (85-95%). The structures of aU the products were established on the basis of physical and spectral properties. 

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