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US 4,225,722 AGranted
Process for the production of 2-(1H-tetrazol-5-yl)-9-hydroxy-1-oxo-1H-naphtho-(2,1-b) pyran and intermediates therefor
AssigneeWarner-Lambert Company
InventorsDavid T. Connor, Patricia A. Young, Maximilian Von Strandtmann
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Abstract
This invention relates to Compounds of formula II: ##STR1## wherein Y is formyl, carboxylic acid, acrylic acid, cyano or tetrazolo; X is hydrogen, lower alkanoyl or lower alkyl, and their non-toxic, pharmaceutically acceptable salts are disclosed. These compounds are useful in the prevention of allergic and asthamatic reactions.
Claims4
A process for preparing a compound of the formula 9:
- ##STR12## which comprises the steps of:
- (A) dissolving a compound of the formula 1:
- ##STR13## in a sufficient amount of acetic anhydride to form a solution, adding boron trifluoride etherate and refluxing for at least 4 hours to obtain a compound of the formula 2:
- ##STR14## (B) after isolation, reacting compound 2 with hydrochloric acid to obtain a compound of the formula 4:
- ##STR15## (C) after isolation, treating Compound 4 with a Vilsmeier reagent prepared from phosphorous oxychloride and dimethylformamide, followed by hydrolysis to obtain compound 5:
- ##STR16## (D) after isolation, refluxing Compound 5 with hydroxylamine hydrochloride and sodium formate in formic acid to obtain Compound 8:
- ##STR17## (E) after isolation, adding aluminum chloride to a suspension of Compound 8 and sodium azide in tetrahydrofuran, refluxing for from about 16 to about 30 hours and acidifying to obtain Compound 9.
4 more elements
Dependencies are inferred from the claim text.