Premium
Stabile Tellur‐Ylide: Darstellung und Reaktivität von Diorganyltelluronium‐4,5‐dicyanimidazol‐2‐yliden
Author(s) -
Tappeiner Günther,
Bildstein Benno,
Sladky Fritz
Publication year - 1991
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19911240405
Subject(s) - chemistry , ylide , reactivity (psychology) , carbanion , medicinal chemistry , wittig reaction , imidazole , diazo , alkylation , onium , carbene , tellurium , phosphonium , polymer chemistry , stereochemistry , organic chemistry , catalysis , medicine , ion , alternative medicine , pathology
Stable Tellurium Ylides: Synthesis and Reactivity of Diorganyltelluronium 4,5‐Dicyanoimidazol‐2‐ylides Diorganyl tellurides R 2 Te (RMe, Me 3 SiCH 2 , Ph) react with 2‐diazo‐4,5‐dicyano‐2 H ‐imidazole ( 1 ) at – 30°C to form the title compounds 2 – 4. The ylides 3 and 4 are thermally stable up to their melting points of 159 and 243°C, resp., whereas 2 undergoes a modified Stevens rearrangement at 190°C with formation of a 2‐(methyltelluro)imidazole ( 10 ). The reactivity of 2 – 4 is determined by an extreme charge separation between the onium centre and the ylide entity. No Wittig reactivity is observed, alkylation occurs at the imidazole nitrogen and carbanions lead to tetraorganyl tellurium compounds with limited stability.