Nitrobenzene → 7-fluoro-5H-indeno[1,2-b]pyridin 5,5-thiazolidine

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Reaction Steps

The process typically involves the addition of 1.1 molar equivalents of the enamine to 1 molar equivalent of bromopropylamine hydrobromide in dimethylformamide at elevated temperature until the exothermic reaction is initiated wherein the temperature is kept at 90°-120° C. for several hours. The product is isolated by a combination of acidification and ether washing followed by basification and ether extractions. Evaporation yields the tetrahydroimine product such as: ##STR60## The tetrahydroimine product is aromatized in xylene and nitrobenzene and 10% palladium on charcoal according to Parcell and Hauch, ibid. The resulting product, e.g., 7-fluoro-5H-indeno[1,2-b]pyridine (which may be further derivatized according to Method V) is derivatized according to Methods II and IV to yield the corresponding spiro-derivatives such as spiro-(7-fluoro-5H-indeno[1,2-b]pyridin-5,5-thiazolidine)-2',4'-dione; spiro-(7-fluoro-5H-inden[1,2-b]pyridin-5,5'-(oxazolidine-2',4'-dione and spiro-(7-fluoro-5H-indeno[1,2-b]pyridin-5,3'-succinimide. Oxidation (Method VII) of 5H-indeno[1,2-b]pyridine or its derivatives according to the method of Sprinzak, J. Amer. Chem. Soc., 80, 5449 (1958) yields the corresponding 5-one or ketone derivative, which may be further derivatized according to Method V. When reacted in accordance with Method I, the ketone will yield a spiro-hydantoin derivative such as spiro-(7-fluoro-5H-indeno[1,2-b]pyridin-5,5'-imidazolidine)-2',5'-dione. Any of the aforementioned spiro derivatives may be further derivatized, e.g., nitrated, in accordance with Method VI. See Examples XVIII, XI and XII.

Provenance & Evidence