Reactions of RSe-EMe3 (E = Si, Ge, Sn, Ph) with XeF2 - RSe-F equivalents in the fluoroselenenylation of acetylenes

Selenides of the type (RSe)-Se-1-EMe3 (E = Si, Ge, Sn, Pb) react with xenon difluoride by cleavage of the Se-E bond to yield the (RSe)-Se-1-F intermed iate and the fluorides Me3E-F, whereas the Se-C bond in PhSe-tBu (E = C) is stable against XeF2. The presence of (RSe)-Se-1-F intermediates is confirm ed by addition to acetylenes (4-octyne, 3-hexyne). Thus, the fluoroseleneny lation of acetylenes gives fluoro(organylseleno)olefins in preparative yiel ds. In the cases of E = Si, Ge, Sn, and Pb, aryl and n-alkyl groups are sui table as the substituent R-1 The X-ray crystal structural analysis of (E)-3 -(p-carboxyphenylseleno)-4-fluorohex-3-ene - the first example of an unchar ged fluoroselenoolefin synthesized from p-EtO2C-C6H4-Se-SnMe3, XeF2, and 3- hexyne followed by an ester hydrolysis - shows that the addition of the sel enenylfluoride intermediate to the acetylene proceeds via a trans-addition, as is known for the R2Se2-XeF2 reagents.