2-Ferrocenyl-2-thiazoline as a building block of novel phosphine-free ligands

Abstract

New 1,2-disubstituted ferrocenes [5(b–j), in which R = –SMe, –SPh, –SiPr, –SiMe₃, –SePh, –SnBu₃, –B(OH)₂, –Me, –I] with a thiazoline ring in the ferrocene backbone using as key intermediate a ferrocenyl Fischer carbene complex were synthesized. The capability of the 2-thiazoline moiety as an ortho-directed metalation group was demonstrated by subsequent quenching of lithium intermediate with several electrophiles, proving to be an excellent method for synthesizing bidentate ligands. The catalytic scope of the [N,S] ligand 5b as the corresponding palladium complex 5b-PdCl₂22 in a microwave-promoted Heck reaction was also tested. Results obtained showed better catalytic activity of 5b-PdCl₂22 compared to other catalytic systems based on a [N,S] ferrocenyl ligand.