No abstract

A new and efficient method for the synthesis of quinazolines has been developed. Thus, N‐[2‐(1‐azidoalkyl)phenyl]formamides 1 are dehydrated with POCl3 to give the corresponding 2‐(1‐azidoalkyl)phenyl isocyanides 2, which are then treated with NaH in DMF at 0° to give quinazolines 6 in satisfactory yields via cyclization of 1‐(2‐isocyanophenyl)alkylideneamine intermediates 4. This methodology can be applied to the synthesis of the 7‐azaanalogs of quinazolines, i.e., pyrido[3,4‐d]pyrimidines 9.

Thioflavones (VI) are prepared by iodine‐mediated cyclization of propenone derivatives (V), which are obtained by an easy two‐step sequence from halophenylethanones (I).

A series of 6‐aminoindolo[2,1‐a]isoquinoline‐5‐carbonitriles 4 have been prepared by treatment of 2‐(2‐bromophenyl)‐1H‐indoles 1, available from 1‐(2‐bromophenyl)ethanones or 1‐(2‐bromophenyl)propan‐1‐ones by using Fischer indole synthesis, with propanedinitrile in the presence of a catalytic amount of CuBr and an excess of K2CO3 in DMSO at 100°.

The title transformation provides benzothiophenimines some of which are further hydrolized to the corresponding benzothiophenones.