Simple Access to Unsymmetrically Substituted, Saturated N-Heterocyclic Carbenes

✍ Scribed by F. Ekkehardt Hahn; Martin Paas; Duc Le Van; Thomas Lügger

• Book ID: 101559174
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 129 KB
• Volume: 42
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.200352349

✦ Synopsis

Since the preparation of the first "unsaturated" (aromatic) carbene 1 (R = 1-adamantyl) [1] in 1991 and the synthesis of the first carbene of type 2 (R = mesityl) [2] in 1995 with a "saturated" (non-aromatic) five-membered ring, stable Nheterocyclic carbenes have become increasingly important in coordination chemistry and catalysis. [3] Meanwhile, additional examples of symmetrically substituted, saturated N-heterocyclic carbenes of type 2 have been described. [4] An acyclic N,N'-stabilized carbene [5] and the benzannulated derivative 3 [6] are known. The latter compound formally includes an unsaturated N-heterocyclic ring but has spectroscopic and structural properties typical for saturated carbenes of type 2 (Scheme 1).