Ruthenium-catalyzed ring-closing metathesis on alkene-tethered Fischer carbene complexes

2398-2405Alkene-terminated tethers have been assembled around a Fischer carbene moiety by C-alkylation of the α-carbon or N-alkylation of amino carbene complexes by a phase-transfer catalyzed procedure developed in this laboratory. Small or medium-sized, pendant, fused or spirocyclic rings have then been formed by ring-closing metathesis involving such substrates in good to excellent yields. By engaging one of the allyl tethers of a diallylamino group as a ligand for the metal center, it is possible to dictate the direction of cyclization by metathesis