Complexos não-carbênicos a base de Ru promovendo a transformação do metil-eugenol através de reações de metátese de olefinas

Abstract

The present work shows the study of the application of two non-carbene Ru-base complexes, [RuCl2(PPh3)2(piperidine)] (LN-1) e [RuCl2(PPh3)2(perhydroazepine)] (LN-2), as initiator in metyl-eugenol (ME) olefin metathesis, in reactions for 48h at 100 ºC, with Ru:substrate ration of 1:100 mol. Reactions were performed in SnCl2 presence or absence in different ratios of 1:1 or 1:2 mol. These complexes were not applied as catalysts in terpenes olefin metathesis, similar to ME, yet these ones already were studied as ROMP initiator, another olefin metathesis reaction type, and showed good results, driving the present research. The results obtained were compared to the first-generation Grubbs metathesis catalyst (G1), this one was tested sob same condition of the synthesis with catalyst of the type LN. As an additional session, it is related the olefin metathesis of the limonene and carvone, which are terpenes similar to the ME, with the intention of evaluating the non-carbene activite in these compounds. All the products formed were analyzed for GC-MS technical, and the results were discussed as a function of the steric and electronic complexes proprieties and the interaction with SnCl2. In SnCl2 absence, the complexes of the type LN presented activity for olefin metathesis of ME with dimeric specie with m/z = 328.00 formation, however with yield less than 1% when LN-1 is the catalyst and c.a. 2% when LN-2 is the catalyst. ME conversion reached 20 and 25% for LN-1 and LN-2, respectively, it is due to formation of isomers and/or products from ME oxidation. In SnCl2 presence, other products from ME olefin metathesis were observed in addition to products formed without additive, also with m/z = 328.00. These compounds are dimeric compounds from ME self-metathesis which form isomers in solution. LN-1 formed primarily a dimer from ME olefin metathesis with c.a. 22% in the mixture in the reactions with ratio Ru:SnCl2 of 1:2, whereas the complex LN-2, in this same condition, formed primarily iso-ME with c.a. 38% in the mixture. No olefin metathesis product was noted in reaction with compound of the type LN in SnCl2 presence with ratio Ru:SnCl2 of 1:1. When the catalysts of the type LN were applied in the olefin metathesis of the limonene or carvone, no metathesis product was obtained. It was reasoned that the aliphatic double-bond these two compounds could be prevented stereochemically. However, test with Hoveyda-Grubbs catalyst (HG), which have a own “Ru-O” pseud-bond that is discoordinated in solution and approximation of the substrate, also no olefin metathesis product was formed.