16804-85-6Relevant articles and documents
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Nelson,W.L. et al.
, p. 3433 - 3436 (1970)
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A New Approach to Asymmetric Synthesis of Polycycles on the Basis of o-Quinodimethane Generation
Ito, Yoshihiko,Amino, Yusuke,Nakatsuka, Masashi,Saegusa, Takeo
, p. 1586 - 1590 (2007/10/02)
The fluoride anion induced 1,4-elimination of 2-phenyl>-3,3-dimethyloxazolidinium salts generates (E,E)-α-alkyl-α'--o-quinodimethane intermediates, which are trapped stereoselectively with dienophiles to give polycycles.Intramolecular cyclization of 2-phenyl>-3,3-dimethyl-4-(R)-methyl-5(R)-phenyloxazolidinium triflate at 0 deg C produces a 3:1 diastereoisomeric mixture of 6--trans-octahydrophenanthrene, which is converted by hydrogenolysis on Pd/C to trans-octahydrophenanthrene with D +46.6 deg (50percent ee).Similarly, intramolecular cyclization of 2-phenyl>-3,3-dimethyl-4(S)-methoxymethyl-5(S)-phenyloxazolidinium triflate produces, after hydrogenolysis on Pd/C, trans-octahydrophenanthrene with D -51.1 deg (55percent ee).The enantioselection in the cycloaddition with o-quinodimethane intermediate may be accounted for on the basis of ?-stacking interaction in the Diels-Alder transition state.
