Preparation from Thiocyanates, Selenocyanates, and Tellurocyanates

Preparation from Thiocyanates, Selenocyanates, and Tellurocyanates.—Less commonly used, but nevertheless well-established, routes to sulphides, selenides, and tellurides are offered by the use of these reagents more space is devoted to the derivatives of the heavier chalcogens. 

Copper (i or ii)-catalysed addition of PhSeCN to an alkene, followed by reaction with an alcohol, gives /rans-yff-alkoxyalkyl phenyl selenides. An extension of this reaction has been used to convert cyclo-octa-1,5-diene into a mixture of the isomeric oxygen-bridged 1,4- and l,5-bis(phenylseleno)cyclo-octanes. The first 

Net sjw-addition, with Markownikov orientation, has been established for the addition of PhSeSCN to (E)- and (Z)-l-phenylpropene under kinetic control, further interest arising in the fact that the (Z)-isomer leads to 2-(phenylselenyl)- 

1- phenylpropyl thiocyanate, while the ( )-isomer gives the corresponding iso-thiocyanate.  

---