Intramolecular free radical functionalisation of the methyl group of 5′-deoxyadenosine

Abstract

Formation (2 methods) of a free radical at the 8-position of 5′-deoxy-2′,3′-O-isopropylideneadenosine causes cyclisation with the 5′-methyl group to give, in yields of up to 80%, 5′-deoxy-2′,3′-O-isopropylidene-5′,8-cycloadenosine, identical with the product formed from the 5′-radical by cyclisation with the 8-position. The reactions provide an in vitro analogy for the functionalisation of the methyl group of 5′-deoxyadenosine postulated as a step in the mechanism of many enzymic coenzyme B₁₂-controlled rearrangement reactions.