Phenanthroindolizidines and related compounds

A new synthesis of the racemic forms of four methoxy substituted phenanthroindolizidines has been accomplished. The structures of two of the synthetic products, the tetramethoxy substituted bases (i)- tylocrebrine (xxxild) and (1)- tylophorine (xxxilc), were confirmed by direct comparison with the naturally occurring alkaloids whilst the spectroscopic data and physical constants of the trimethoxy base (xxxilb) were in agreement with those published for (-)-antofine and (-)-antofine. The fourth synthetic base, the dimethoxy substituted phenanthroindolizidine (XXXlla), was new and its proposed structure was confirmed by standard analytical and spectroscopic methods.