1.3- Diynes selenophenes

Addition of hydrogen selenide and hydrogen telluride to diynes has been used for the synthesis of selenophenes and tellurophenes. 

Furan also undergoes a primary [4+2] cycloaddition with 3, but this is followed by a [2+1] addition of 2 to the newly formed double bond to furnish the isolated tricyclic compound 5. Thiophene behaves differently its reaction with 3 furnishes the disilathiirane 6 as a formal sulfur-abstraction product [3]. This strongly divergent behavior of five-membered ring systems prompted us to investigate the photolyses of 1 also in the presence of a selenophene, a tellurophene, and a pyrrole. We report here on the photolysis of 1 in the presence of these cyclic dienes as well as similar reactions with acyclic diynes. 

Rh(PPh3)3Cl to diyne (115). A similar reaction occurs with the diene (116). Conversion of these rhodium species into cyclopentadienones (with carbon monoxide) or into substituted furans, thiophens, or selenophens (with oxygen, sulphur, or selenium, respectively) can be effected. ... 

A number of synthetic methods have developed for construction of the heterole skeletons. The most straightforward and atom-economical method for the synthesis of 2,5-disubstituted heteroles is the double addition of X—H bonds across 1,3-diynes, albeit it requires trans addition to the carbon-carbon triple bonds. Thiophenes [2], selenophenes [3], teUurophenes [4], phospholes [5], arsoles [6], and stannoles [7] have been synthesized by using this method without the aid of catalysts ... 

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