ISSN:
0021-8383
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Pyrylium Compounds. 42. Benzocycloalkenones and Dihydro-2H,7H-1-benzopyranones from 2,4,6-Triarylpyrylium Salts and Cycloalkane-1,2-diones2,4,6-Triarylpyrylium salts 1 react with cycloalkane-1,2-diones 2 in the presence of an appropriate condensing agent to yield benzocycloalkenones 3. Thus, sodium acetate and cyclo-hexane-1,2-dione (2a) lead to the dihydro-2H-naphthalenones 3a-i, whereas with cycloheptane-1,2-dione (2b) and piperidine acetate, triethylamine or sodium acetate the tetrahydro-5H-benzo-cyclohepten-5-ones 3j-r are formed. As shown for the example 3a, j → 4a, b, benzocycloalkenones of type 3 can be converted into phthalazines 4 on heating with hydrazine in ethanol. By reaction of the dione 2a and an equimolar mixture of triethylamine and acetic acid or morpholine acetate with the salts 1 5,6-dihydro-2H,7H-1-benzopyran-8-ones 5 are obtained as a result of a new type of ring transformation. The pyrans 5 can be cleaved with perchloric acid in ethanol to 5,6,7,8-tetrahydro-8-oxo-1-benzopyrylium perchlorates 6. If the pyrans 5 are heated with sodium acetate in ethanol, a conversion to benzocycloalkenones 3 is achieved (cf. 5a → 3a). The structure of the new compounds was established by spectroscopic methods.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.19893310217
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