Towards Sustainable Catalysis – Highly Efficient Olefin Metathesis in Protic Media Using Phase Labelled Cyclic Alkyl Amino Carbene (CAAC) Ruthenium Catalysts

Abstract

New generations of Hoveyda and bis‐carbene type of ruthenium‐based olefin metathesis catalysts (10 and 12), containing cationic cyclic alkyl amino carbene (CAAC) ligands, have been synthetized. The catalysts show exceptional stability and activity in environmentally benign, protic media. Various olefin metatheses reactions of OH functionalized feedstock (e. g. RCM, ROMP CM) can be carried out at as low as 0.05 mol % catalyst loading in methanol, isopropanol, water or methanol/water solvent mixture, accomplishing the lowest applied catalyst loading reported so far in these media. The facile olefin metathesis of renewable feedstocks including phospholipids (23) and vegetable oils (20) in protic media has also been demonstrated.

Cyclic (Alkyl)(amino)carbenes (CAACs) in Ruthenium Olefin Metathesis

“…Note that the reaction can also be achieved under protic conditions in methanol using the more polar Ru-45. 36…”

Synthesis and Characterization of Novel PEPPSI type Pd–BICAAC Complexes

“…Compound 2b was synthetized following the procedure described in a paper published by our group recently. 30 GC-MS analyses were carried out using a Shimadzu GC-MS-QP2010 instrument fitted with an Rxi-5Sil MS column coupled with a quadrupole mass filter with pre-rods.…”

Stable CAAC‐based Ruthenium Complexes for Dynamic Olefin Metathesis Under Mild Conditions

“…As all reactions were performed under identical conditions, these results indicate the improved tolerance of CAAC catalysts to protic solvents, which has also been recently applied in aqueous olefin metathesis. [49] In addition to alcohols, several other classes of compounds are known to be detrimental to olefin metathesis catalysts. [41,50,51] A recent study focusing on the decomposition of catalyst HGII and CAAC-based catalysts by equimolar amounts of nucleophiles, described a variety of decomposition mechanisms and values of amine tolerance in the range of 60-100 %.…”