Complex Thiopyran and Selenopyran Derivatives

Work on thienothiopyrans of various types continues. Syntheses have been reported for the following compounds (91), (92 R = H or Me) and 

Some thiopyrano[4,3-Z ]benzofurans have been described and numerous systems with nitrogen-containing fused rings have been reported, including the indole derivatives (101) and (102), (103) and (104), and (105), other structures incorporating dihydropyridone (106) and pyrazole (107) rings, and more complex systems, for example (108).  

A comprehensive review of thiepins and thiepin oxides has appeared recently.  

Recent calculations predict thiepin to be antiaromatic and, indeed, this compound has not yet been synthesized. Previous studies have shown that 

Reagents i. Maleic anhydride-C He, 25 °C ii, DDQ-benzene, room temperature iii, MeOH iv, CHjN  

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