New air-stable ruthenium olefin metathesis precatalysts derived from bisphenol S

Synthesis and screening of catalytic activity of novel mono- and diruthenium carbene complexes 7a and 7b prepared from inexpensive Bisphenol S via Claisen rearrangement–isomerisation route is described. These catalysts constitute an excellent tool for ring-closing metathesis by combining high stability with increased catalytic activity as compared with the parent Hoveyda–Grubbs catalyst.