Conformational Analysis of Furyl- and Thienylhydroxymethyl Radicals

Article abstract of DOI:10.1021/jo00048a033

Low-temperature photolysis of ArCH2OH derivatives (Ar = 2- and 3-furyl and -thienyl) in the presence of Bu^tOOBu^t yields the corresponding ArCHOH radicals which can be observed by means of EPR spectroscopy.Each radical displays E and Z rotational conformers due to restricted Ar-C_α rotation.The study of ArCHOMe radicals, as well as of 2-furyl- and 2-thienylhydroxymethyl radicals having a methyl group in position 3 of the ring, allowed us to identify the most stable of the two conformers.The temperature dependence of the α_OH hfs constant (assigned by deuterium substitution) has been interpreted on the basis of an averaging of ab initio α_OH hfs constant over the rotation about the C_α-O bond which also allowed us to obtain an estimate of the corresponding rotation barrier.