Br. Babu et Dv. Ramana, NOVEL SYNTHESIS OF TETRACYCLIC HETEROGONANE RING-SYSTEMS, Phosphorus, sulfur and silicon and the related elements, 74(1-4), 1993, pp. 463-464
Total synthesis of tetracyclic heterogonane ring systems(1,2 & 3) were
achieved from 1-oxo-4-thia-1,2,3,4-tetrahydrophenanthrene(4) and its
oxa analogue(5).