Some pentose and hexose sugars were converted into unsaturated
ketone derivatives, which themselves served as substrates for 4-exo-trig radical
cyclisation reactions mediated by SmI2. Depending on
the order of addition of reagents, the keto-olefins could also be
made to undergo a surprising tandem 5-endo-trig cyclisation/dimerisation
reaction to a cyclopentane dimer or a cyclobutane monomer.
carbocycles - carbohydrates - radical reactions - samarium - ring closure