CCα Insertion: Insertion of an Alkyne into the CC Single Bond between the Carbene-Carbon Atom and the α-Carbon Atom of a Fischer Carbene Complex by an Unprecedented Metalla(di-π-methane) Skeletal Rearrangement

✍ Scribed by Seda Ünaldi; Rudolf Aumann; Roland Fröhlich

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 292 KB
• Volume: 9
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200304767

✦ Synopsis

Abstract

The first examples of insertion of a CC bond of an alkyne into a C~carbene~C~α~ single bond of a carbene complex (CC~α~ insertion) are reported. (__prim‐__Alkyl)carbene complexes [(OC)~5~MC(OEt)CH~2~R] (1 a–f; M=Cr, W; R=__n__Pr, C~7~H~7~, Ph) undergo CC~α~ insertion of electron‐deficient alkynes [PhCCC(XEt)NMe~2~]BF~4~ (5 a,b; X=O, S) to give zwitterionic carbiminium carbonylmetalates 3 a–g, which are thermally transformed into (CO)~4~M chelate carbene complexes 4 a–g by elimination of CO. The overall reaction is highly regio‐ and stereoselective. It involves an unprecedented metalla(di‐π‐methane) rearrangement as the key step.