Diels-Alder Reactions of Cycloalkenones. 8. A One-Step Preparation of 4,4-Dimethyl-1-Octalones, Useful Intermediates in Terpene Synthesis

References and Notes

• Fringuelli , F. , Pizzo , F. , Taticchi , A. , Wenkert , E. , Pizzo , F. , Taticchi , A. , Halls , T. D. J. , Wenkert , E. , Minuti , L. , Pizzo , F. , Taticchi , A. , Halls , T. D. J. , Wenkert , E. , Pizzo , F. , Taticchi , A. , Wenkert , E. , Pizzo , F. , Taticchi , A. , Ferreira , V. F. , Michelotti , E. L. , Porter , B. , Wenkert , E. , Fringuelli , F. , Minuti , L. , Pizzo , F. , Porter , B. , Taticchi , A. , Wenkert , E. , Fringuelli , F. , Halls , T. D. J. , Pizzo , F. , Porter , B. , Taticchi , A. , Tourris , A. P. , Wenkert , E. , Fringuelli , F. , Pizzo , F. , Porter , B. , Taticchi , A. and Wenkert , E. Ibid. , in press
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• Complete structure analyses mainly by 13C NMR spectroscopy and satisfactory elemental analyses were obtained for all new substances
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• Gc analyses were performed on a Hewlett-Packard 5880-A Chromatograph with a 25 m 0.2 mm diameter SE-30 bonded phase capillary column, an “on-column“ injection system and hydrogen as the carrier gas
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• It is noteworthy that insertion of one more double bond into the enones 1, i.e. the use of 4,4–dimethyl-2,5-cyclohexadienones in the acid–catalyzed reactions with isoprene reintroduces high regioselectivity, albeit leading to adducts of structure type 4.1c
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• Wenkert , E. and Naemura , K. 1973 . Synth. Commun. , : 45 For an earlier synthesis of the himachalenes, utilizing an intramolecular version of the acid–catalyzed Diels-Alder reaction
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