Alkylation and an unusual reductive ring opening of some thieno[3,4-b][1,5]benzoxazepin-10-ones

As part of a program towards the syntheses of novel tricyclic compounds, some derivatives of thieno3,4-b]-1,5]benzoxazepin-10-one system 1 were prepared and were subsequently subjected to reduction reactions using lithium aluminum hydride. Although thienobenzoxazines 4 were obtained as the sole product of the reduction in most cases, unusual ring-opened products, namely 3-hydroxymethylthiophenes 5 , were also formed during several reductions.