An efficient method for the synthesis of the thieno[2,3-c:4,5-c']dipyr
role ring system is described. Reaction of 13 with sodium azide follow
ed by the treatment with triphenylphosphine and water gave parent comp
ound 4. Reaction of 13 with benzylamine or aniline afforded N,N'-disub
stituted derivatives 15 and 16 respectively. Diels-Alder reaction of 1
5 with DMAD gave cycloadducts 17 and 18. Oxidative removal of the imin
e bridge from 17 and 18 gave dibenzothiophene 19.