The reactions of the acyclic diaminocarbenes (Me2N)2C and (Ph2N)(iPr2N)C with CO proceed in a 2 : 1 stoichiometric ratio, affording unprecedented betainic oxyallyl species of type [(R2N)2C]2CO.

The "Alder carbene" (iPr(2)N)(2)C undergoes a β-fragmentation in solution already at room temperature, affording propene and N,N,N'-triisopropylformamidine. This stands in sharp contrast to the indefinite stability previously claimed for this iconic compound.

Diisopropylamino-cis-2,6-dimethylpiperidinocarbene reacts regio- and diastereoselectively with CO to afford a bicyclic β-lactam with 100% atom efficiency, whose spectrum of activity resembles that of penicillin G or amoxicillin.

No abstract

A combined experimental and theoretical study on the reaction of Si 2 Br 6 with N-heterocyclic carbenes is reported. Employment of an imidazole-2-ylidene with methyl groups in C 4 -and C 5 -position results in the disproportionation of Si 2 Br 6 into the adducts NHCǞSiBr 2 and NHCǞSiBr 4 . According to expectation, the hydrogenated derivative 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene