Microwave-promoted and Lewis acid catalysed synthesis of steroidal A- and D-ring fused 4,6-diarylpyridines

The preparation of novel steroidal heterocycles containing 4,6-diaryl substituted pyridine moiety fused to the 2,3- and 16,17-positions of the steroid nucleus is described. The Michael reaction of steroidal ketones (1a, 1b and 1c) with in situ generated chalcones provided the intermediates 3,5-diaryl-1,5-dicarbonyl steroidal derivatives (4a–s). Subsequently, the intermediates 4a–s were converted to the pyridine derivatives (5a–s) by solid phase reaction with urea in presence of BF3.OEt2 as the catalyst under microwave irradiation. All the synthesized heterosteroids are new compounds and are currently being evaluated for their biological activities.

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► New steroidal 1,5-diketo compounds were synthesized in A and D ring.
► These diketo compounds were converted to new steroidal pyridine derivatives.
► Solid phase reaction and microwave irradiation were used in this synthesis.
► The structures of these new compounds were determined by IR, NMR and MS.