A ROMP-derived, polymer-supported chiral Schrock catalyst for enantioselective ring-closing olefin metathesis

A permanently polymer-immobilised version of Schrockʹs molybdenum catalyst was realised via polymerisation of chiral 5,5ʹ-bis(norborn-5-ene-2-ylmethyleneoxymethyl)-3,3-di-tert-butyl-6,6ʹ-dimethylbiphen-2,2ʹ-diol followed by reaction with the catalyst precursor Mo(N-2,6-i-Pr2C6H3)(CHCMe2Ph)(OSO2CF3)2(CH3OCH2CH2OCH3); using this 5-, 6- and 7-membered heterocycles were synthesised via ring-closing metathesis (RCM) from (pro-)chiral substrates in high yields and ee with short reaction times; the catalyst shows low loss of molybdenum during RCM, and was easily separated and recycled.