An Asymmetric Total Synthesis of D-Homo Steroids Involving a Lewis Acid Directed Diels-Alder Reaction

References

• Hajos , Z. G. and Parrish , D. R. 1974 . J. Org. Chem. , 39 : 1615 Z. G. Hajos and D. R. Parrish, W. German Patent 2,102,623 (Hoffmann-La Roche) (July 29, 1971) Chem. Abstr., 75, 129414r (1971)
   Web of Science ®Google Scholar
• Eder , U. , Sauer , G. and Wiechert , R. 1971 . Angew. Chem., Int. Ed. Engl. , 10 : 496
   Web of Science ®Google Scholar
• Cohen , N. 1976 . Acc. Chem. Res. , 9 : 412 and references cited therein. See also
   Web of Science ®Google Scholar
• Gutzwiller , J. , Meier , W. and Fürst , A. 1977 . Helv. Chim. Acta , 60 : 2258
   PubMed Web of Science ®Google Scholar
• Pandit , U. K. and Bieräugel , H. 1976 . Rec, Trav, Chim. Pays-Bas , 95 : 223
   Google Scholar
• Eder , U. , Haffer , G. , Neef , G. , Sauer , G. , Seeger , A. and Wiechert , R. 1977 . Chem. Ber. , 110 : 3161
   Google Scholar
• Neef , G. , Eder , U. , Haffer , G. , Sauer , G. , Wiechert , R. and Schönholzer , P. 1977 . ibid. , 110 : 3377
   Google Scholar
• Hajos , Z. G. and Parrish , D. R. 1974 . J. Org. Chem. , 39 : 1612
   Web of Science ®Google Scholar
• Ruppert , J. , Eder , U. and Wiechert , R. 1973 . Chem. Ber. , 106 : 3636 See for an approach related to the present work
   Google Scholar
• Prelog , V. and Acklin , W. 1956 . Helv. Chim. Acta , 39 : 748
   Web of Science ®Google Scholar
• Gutzwiller , J. , Buchschacher , P. and Fürst , A. 1977 . Synthesis , 2b : 167 We are grateful to these authors for providing us with details of their work prior to publication and for samples of
   Google Scholar
• Akhrem , Cf. A. A. and Titov , Y. A. 1970 . “ 2 ” . In Total Steroid Synthesis New York : Plenum Press . Cha
   Google Scholar
• Dickinson , R. A. , Kubela , R. , MacAlpine , G. A. , Stojanac , Z. and Valenta , Z. 1972 . Can. J. Chem. , 50 : 2377
   Web of Science ®Google Scholar
• Stojanac , Z. , Dickinson , R. A. , Stojanac , N. , Woznow , R. J. and Valenta , Z. 1975 . ibid. , 53 : 616
   Google Scholar
• Nazarov , I. and Gurvich , I. A. 1955 . Zh. Obshch. Khim. , 25 : 956 The racemic modification of this material has been reported previously
   Google Scholar
• 1972 . The structure of (pm)-9 has been confirmed by its conversion into (pm)-5α-pregnane-3,20-dione:U. S. Patent No. 3,920,748 (Hoffmann-La Roche), June 12, Chem. Abstr., 84, p 122144e (1976)
   Google Scholar
• Doyle , Cf. M. P. , Williams , S. B. and McOsker , C. C. 1977 . Synthesis , : 717 in which it is stated,“Attempts to employ boron trifluoride as a catalyst for the dehydration of alcohols have not been successful”
   Google Scholar
• The use of tetrahydrofuran is essential. Attempted dehydration in pure benzene led to polymerization
   Google Scholar
• Since both the dehydration of 5 and subsequent Diels-Alder reaction are Lewis acid catalyzed, a one step procedure was investigated (racemic series) in which the dehydration was carried out in the presence of quinone 8. Although this process did, in fact, lead to (pm)-9, the yield was low due to the formation of by-products at the elevated temperature required for the dehydration
   Google Scholar
• Izumi , Y. 1971 . Angew. Chem., Int. Ed. Engl. , 10 : 871
   Web of Science ®Google Scholar