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Generating new catalysts

A new method to functionalize N-heterocyclic carbenes
Generating new catalysts

Functionalized heterocyclic carbene

Oeiras, 17.06.9

Carbene molecules are an extremely reactive class of compounds with increasing applications as catalysts in the chemical industry. In fact, since the successful isolation of a stable N-heterocyclic carbene (NHC) there has been a spectacular interest in this class of ligands. ITQB researchers from the Laboratory of Homogeneous Catalysis in collaboration with Universitat Jaume I in Castellón (Spain) have prepared the first NHC-functionalized with a cyclopentadienyl ring. This new molecule can be combined with late transition metals by metallation to catalyse a wide set of reactions. The results can be found online in the journal of Dalton Transactions.

New catalyst systems that allow for rapid and selective chemical transformations have a significant impact in the chemical industry minimizing energy consumption and waste. Because stable N- heterocyclic carbenes are powerful electron donors and can bind strongly to the metal in a complex, they are exceptionally useful spectator ligands in catalysis, surpassing the traditionally used phospines both in activity and scope. And just as phosphines, NHCs can be designed to carry functional groups thus altering their catalytical properties. The novel metal-based species prepared in this work display high catalytic activity in the β-alkylation of secondary alcohols and amines with primary alcohols: a catalytic system for environmentally benign synthesis of amines and alcohols with the formation of only water as a byproduct.

The methodology described in this work constitutes a valuable protocol for the preparation of NHC – late transition metal complex that can be extended to the preparation of complexes with other transition metals for different applications.

Original paper:

Dalton Trans, 2009, DOI: 10.1039/b901195a

Easy preparation of Cp*-functionalized N-heterocyclic carbenes and their coordination to rhodium and iridium

André Pontes da Costa, Mercedes Sanaú, Eduardo Peris and Beatriz Royo

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