References
- 1969–1971 . Purdue University . David Ross Research Fellow
- 1967–1969 .
- Hercules, Inc. Fellow . 1967–1968 .
- Cook and Hewett4 reported that the stannic chloride catalyzed condensation of phenylacetyl chloride and cyclohexene gave phenylacetylcyclohexene and no tricyclic ketone. Gutsche and Johnson5 using aluminum chloride in refluxing carbon disulfide obtained a 10% yield of crystalline product formulated as a “keto-hydrophenanthrene”. The negative results and poor yields reported by these investigators apparently discouraged further use of this Friedel-Crafts type sequence in the synthesis of hydrophenanthrene derivatives. We have repeated Cook's work (using SnCl4 in CS2) and have confirmed the absence of tricyclic ketones in the reaction products. We have also reproduced Gutsche and Johnson's results, however, the crystalline “ketone” does not appear to be a hydrophenanthrene derivative and is currently under investigation. We find that the condensation of the aluminum chloride complex of phenylacetyl chloride with cyclohexene affords a mixture of cis and trans-ketohydrophenanth-renes in 50–55% yield. Similarly, phenylacetyl chloride condenses with methylcyclohexene using stannic chloride or the aluminum chloride complex in methylene chloride to yield a mixture of 5α and 5β-19,20-nor-podocarpa-8,11,13-triene-6-ones in 60–65% yield
- Cook , J. W. and Hewett , C. L. 1933 . J. Chem. Soc. , : 1098
- Gutsche , C. D. and Johnson , W. S. 1946 . J. Am. Chem. Soc. , 68 : 2239
- Burckhalter , J. H. and Campbell , J. R. 1961 . J. Org. Chem. , 26 : 4342 For other intermolecular-intramolecular Friedel-Crafts alkylations see: W. A. Smit, A. V. Semenovsky, V. F. Kucherov, T. N. Chernova, M. Z. Krimer, Tetrahedron Letters, 3101 (1971)
- Braudt , C. W. and Neubauer , L. G. 1939 . J. Chem. Soc. , : 1031 F. D. King, B. J. King and J. G. Topliss, J. Chem. Soc., 573 (1957), R. Rao and K. Raman, Tetrahedron, 4, 294 (1958)
- Bredenbery , J. B. and Gripenberg , J. 1956 . Acta. Chem. Scand. , 10 : 1511 D. Nasipuri and M. Guha, J. Chem. Soc., 4248 (1962)
- 1,3,3-Trimethylcyclohexene (2) was obtained from thermal decarboxy-lation of 3-carboxy-2,4,4-trimethylcyclohexene which was prepared by acid catalyzed cyclization of geranic acid
- A variety of Lewis acids can be used in promoting the reaction formulated in Equation 1, however, in this instance, aluminun chloride, stannic chloride, titanium tetrachloride and zinc chloride isomerize 1 to 1,5,5-trimethylcyclohexene which then condenses to give hydrophenanthrene derivatives with the gem-dimethyls at C2. Use of a freshly filtered solution of complex 2 appears to avoid or at least minimize the isomerization of olefin 1 thus permitting the formation and isolation of the desired ketone 3
- Fetizon , M. and Moreau , G. 1965 . Bull. Soc. Chim. France , : 3479
- We express our gratitude to Professor E. Wenkert, Indiana University, for a sample of (+) ferruginol
- Mahapatra , S. N. and Dodson , R. M. 1963 . Chem. and Ind. , : 253
- Kondo , Y. , Ikenoue , T. and Takemoto , T. 1963 . Chem. Pharm Bull. , 11 : 678