Heterocyclic Spiro-naphthalenones. Part II. Synthesis and reactions of some spiro [tetrahydrofuran-2,1′-(2′H-naphthalene)]-2′,5-diones and Spiro [tetrahydrofuran-2,2′-(1′H-naphthalene)]-1′,5-diones |
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Authors: | Daniel Berney Karlheinz Schuh |
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Abstract: | The spiro-lactone 3 was obtained by N-bromosuccinimide (NBS) oxidation of the carboxylate 2 at ? 20°. When 2 was oxidized at 10° the spiro-lactone 4 was the main product. Compound 4 was rearranged with triethylamine to the spiro-lactone 9 whereas the stereoisomeric spiro-lactones 14 and 15 were obtained by NBS oxidation of the carboxylate 13 . The ketones 3, 4, 9, 14 and 15 were reduced with NaBH4 to the corresponding alcohols 5, 6, 10, 16 and 18 respectively; these were hydrogenated to the alcohols 7, 8, 11 and 20 . The allylic alcohols 5 and 6 gave the benzochromanone 1 when heated in polyphosphoric acid whereas the benzochromanones 12 and 21 were obtained from the alcohols 10 and 16 respectively. |
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