Studies in the Rearrangement of Spiranes : Part III-Synthesis of 1 ,2,3,4- Tetrahydronaphthalene 2,2-Spiro-(2' ,3 '-dimethylcyclopentane) and its 7-Methyl Derivative and their Rearrangement on Catalytic Dehydrogenation1

Department of Chemistry, Presidency College, Calcutta-12 Manuscript received 17 October 1973; accepted 1 March 1974 The spiranes 1, 2, 3, 4-tetrahydronaphthalene-2,2-spiro-(2',3'-dimethyl cyclopentane) (II, R = H) and its 7-methyl derivative (II, R = CH3) have been synthesised. When heated with 10% Pd-C, they underwent rearrangement yielding 1,2-dimethyl- and 1,2,6-trimethylphenanthrene respectively. The spiranes have been prepared by the AlCl3 -catalysed condensation of the anhydride of 2,3-dimethylcyclopentzane-1-carboxyl-acetic acid (ill) with benzene and toluene. The resulting keto-acids on catalytic reduction under mild pressure followed by cyclisation and reduction afforded the desired spiranes