D. Crich et al., THE CHEMISTRY OF CYCLIC TAUTOMERS OF TRYPTOPHAN - TOTAL SYNTHESIS OF (-(ENT)-PSEUDOPHRYNAMINOL()), Tetrahedron, 51(23), 1995, pp. 6379-6384
A diastereoselective synthesis of the unnatural (+)-enantiomer of the
hexahydropyrroloindole alkaloid (-)-pseudophrynaminol (3), isolated fr
om the skin of the Australian frog Pseudophryne coriacea, from a cycli
c tautomer (1) of L-tryptophan, is described, The CD spectrum of the s
ynthetic 3 is opposite in sign to that of the natural material enablin
g the configuration of the natural product to be established as 3aS,8a
R.