The thorpe-ingold effect in the synthesis of tetrahydro-furans and pyrans by competitive cyclisation with phenylthio migration
摘要:
In cyclisations of triols with two tethered hydroxyl nucleophiles (giving ethers by acid-catalysed phenylthio migration) a gem-dimethyl group in the carbon chain bearing one of the OH groups favours cyclisation of that chain whether the new ring is five- or six-membered and whether the cyclisation is exo or endo in the Baldwin sense.