References
- Diels-Alder Reactions of Cycloalkenones 21
- Minuti , L. , Radics , L. , Taticchi , A. , Venturini , L. and Wenkert , E. 1990 . J. Org. Chem. , 55 : 4261
- Taticchi , A. and Fringuelli , F. 1971 . J. Chem. Soc. (C) , : 297
- Grimshaw , J. , Grimshaw , J. T. and Juneja , H. R. 1972 . J. Chem. Soc. Perkin I , : 50
- Hobbs , P. D. and Magnus , P. D. 1973 . J. Chem. Soc. Perkin I , : 2879
- Since (+)-β-pinene can be prepared starting from commerical (+)-β-pinene6, apoverbenone is available in both (+) and (-) forms
- Andrianome , M. and Delmond , B. 1985 . J. Chem. Soc. Chem. Commun. , : 1203
- Kato , M. , Vogler , B. and Tooyama , Y. 1990 . Chem. Lett. , : 131
- Angell , E. C. , Fringuelli , F. , Minuti , L. , Pizzo , F. , Taticchi , A. and Wenkert , E. 1986 . J. Org. Chem. , 51 : 5177
- Das , J. D. , Valenta , Z. , Liu , H. J. and Ngooi , T. K. 1984 . Can J. Chem. , 62 : 481
- Fringuelli , F. , Taticchi , A. and Wenkert , E. 1990 . Org. Prep. Proc. Int. , 22 : 131
- All formulae are depicted in their correct absolute configuration
- A previous paper12 showed that when cycloalkenones and (E)-1-methoxy-1, 3-butadiene interacted under the influence of strong Lewis acids, resinous materials were produced and only traces of adducts were detected. Consequently the cycloadditions with this diene must be performed either under thermal conditions or in the presence of mild catalysts
- The predominant elimination of methanol from anti-exo adduct 5b was shown as follows: i) treatment of pure samples of antiexo 5b and anti-endo 6b adducts under thermal reaction conditions showed that both of them afforded dienone 9, but ketone 5b eliminated easier than isomer 6b; d) over time the concentration decrease of adducts 5b and 6b was commensurate with concentration increase of dienone 9, as shown by g. c. monitoring. Furthermore both ketones 5b and 6b eliminated methanol easily by treatment with ethanolic sodium ethoxide solution. Elimination of methanol had been previously observed under acid conditions12. The predominant elimination from anti-exo adduct 5b seems to be surprising; an explanation, but probably not the whole reason, is that it depends on the half boat conformation of the ring and the thermal reaction conditions
- Fringuelli , F. , Minuti , L. , Radics , L. , Taticchi , A. and Wenkert , E. 1988 . J. Org. Chem. , 53 : 4607
- Fringuelli , F. and Taticchi , A. 1990 . “Dienes in the Diels-Alder Reaction” , New York : Wiley .
- Sauer , J. and Sustmann , R. 1980 . Angew. Chem. Int. Ed. Engl. , 19 : 779
- Ginsburg , D. 1983 . Tetrahedron , 39 : 2095
- Thomas , A. G. , Di Giorgio , R. and Guntern , O. 1989 . Helv. Chim. Acta , 72 : 767
- The letters A and B are used to distinguish sterically different hydrogens of the methylene groups. In the case of hydrogens at C-11 the letter B indicates the hydrogen atom oriented towards cyclohexenone ring
- Fringuelli , F. , Pizzo , F. , Taticchi , A. and Wenkert , E. 1983 . J. Org. Chem. , 48 : 2802