Synthesis of Dihydrothiophene, Thiophene, and Their Selenium Analogues Carrying Four Phosphoryl Groups

[reaction: see text] Sodium hydrosulfide undergoes addition to two molecules of bis(diethoxyphosphoryl)acetylene followed by cyclization to give a 2,3-dihydrothiophene carrying four phosphoryl groups. Oxidation of the 2,3-dihydrothiophene with mCPBA gives the corresponding sulfoxide or sulfone depending on the ratio of the reagents, and the sulfoxide is dehydrated to afford a tetraphosphorylthiophene. The corresponding dihydroselenophene and selenophene are also synthesized in a similar manner.