Efficient One-Pot Synthesis of Dithieno(dibenzothieno)-Fused Cycloheptanones, Tropones, and Cyclooctanones.
The reactions of alpha,beta-unsaturated amide/triflic anhydride complexes (generated in situ from the corresponding amides and triflic anhydride) with dithiophenes and dithienylmethanes proceed as tandem alkylation-Vilsmeier-Haack acylation to form dithieno- and dibenzothieno-fused cycloheptanones and cyclooctanones in moderate to good yields. The reactions of 2-bromo-N,N-dimethylacrylamide/triflic anhydride complex allow preparation of tropones in a simple one-pot procedure. The reaction of 2,2-dibenzothienylmethane with dimethylacrylamide/triflic anhydride complex proceeds unusually to afford dimethylaminonaphthalene in addition to the predictable fused cyclooctanone.
Nenajdenko
Valentine G.
VG
Department of Chemistry, Moscow State University, Moscow 119899, Russia.
Baraznenok
Ivan L.
IL
Balenkova
Elizabeth S.
ES