A S h o r t S y n t h e s i s o f P y r i d o [ 5 , 6 ] p y r a n o [ 2 , 3 -c ] p y r a z o l -4 ( 1 H ) -o n e s Abstract: An efficient and generally applicable synthesis of various [5,6]pyrano[2,3-c]pyrazol-4(1H)-ones by the reaction of either 1-substituted or 1,3-disubstituted 2-pyrazolin-5-ones with different o-halopyridinecarbonyl chlorides or with 3-chloroquinoline-2-carbonyl chloride, using calcium hydroxide in 1,4-dioxane, is described.In the course of the preparation of pyrazolo[4¢,3¢:5,6]pyrano[2,3-c]pyridin-4(1H)-ones, the intermediate 4-(3-chloroisonicotinoyl)-1H-pyrazol-5-ols did not cyclize spontaneously and thus were transformed into the corresponding tricycles by treatment with NaH in DMF. The N1-unsubstituted title compounds were obtained upon treatment of the corresponding 1-(4-methoxybenzyl) protected congeners with trifluoroacetic acid. Table 4 Selected 13 C-1 H Spin-Coupling Constants (Hz) of 7a-c, 7f, 8a-c, 9a-c, 10a-e, 11f (Solvents as in Table 28a other couplings G. A. Eller et al. PAPER Synthesis 2006, No. 24, 4219-4229 © Thieme Stuttgart · New York 1 H NMR (300 MHz, DMSO-d 6 ): d = 7.67 (m, 3 J

No abstract

Two Pyrano[2,3-c]pyrazol-4-(1H)one Moieties. -The synthesis of the hitherto unknown polyheterocycles (IV) and (VI) is reported. -(ELLER*, G. A.; WIMMER, V.; HOLZER, W.; Chem.

No abstract

No abstract