No abstract

6‐Amino‐2‐thioxotetrahydropyrimidine‐5‐carbonitrile derivative 2 was synthesized in a good yield via refluxing a mixture of arylidene 1 and thiourea in a highly basic sodium ethoxide solution. Subsequently, the synthesized pyrimidine‐2‐thione derivative 2 was allowed to interact with diversified nucleophiles and electrophiles under various reaction conditions in order to have a feasible access to further new and assorted fused heterocycles. Finally, the biological activity of the newly synthesized fused pyrimidines was screened in vitro against four different Gram‐positive and Gram‐negative bacterial strains. All the developed heterocycles were adequately characterized utilizing 1H‐NMR, 13C‐NMR, Fourier transform infrared, elemental analysis, and electrospray ionization–mass spectrum and tested for their antibacterial activity.

Die Cyclohexanderivate (I) und (IIIa) entstehen durch Grignard‐ Reaktionen auf dem angegebenen Weg.

Several new pyridones, pyrazolo [ 1,5-a]pyrimidines and pyrazolo [ 1,5-b]oxazines were prepared from the cyanoacetohydrazide derivatives 1 , l l and the cinnamonitrile derivatives 2a-c. The considerable biological activities of both pyridones and pyrazoles have stimulated enormous interest in the synthesis and chemistry of this class of compounds'.'). As a part of a medicinal chemistry program3.') in our laboratories, the syntheses of several pyridones, pyrazolo[l,5-a]pyrimidines and pyrazoto[ 13-bloxazines were required.In conjugation of this work, we report here on the reaction of cyanoacethydrazide (1) with the cinnamonitrile derivatives 2 a c . Thus, it has been found that 1 reacts with benzylidenemalononitrile (2a) to yield an 1:l adduct. Several isomeric cyclic and acyclic structures seemed possible for the reaction product. Acyclic structures 3 and 4 were readily eliminated based on the 'H-NMR spectrum of the product which revealed only one singlet proton at 6 = 5.6 ppm. Acyclic structures 3 and 4 should have revealed multiplets for more

Several new pyridones, pyrans, pyrazolo [4,3-b]pyrans and isoxazolo [4,3-b]pyrans were prepared from the chalcones 2a,b and activated methylene compounds. The biological activity of pyrazole and pyridine derivatives is well established and attempts have been made earlier to obtain more active and less toxic pyrazole and pyridine derivatives'"). In continuation of our medicinal chemistry project for development of new procedures for the synthesis of pyridines, pyrans, pyrazolo [4,3-b]pyrans and isoxazolo[4,3-b]pyrans we report, here, the possible utility of cyanoacetanilide (1) for the synthesis of azoles and azolines. Aktivierte Nitrile in der heterocyelisehenThus, it has been found that 1 reacted with the appropriate aldehyde to yield the chalcones 2a,b. On the other hand, the pyridone derivatives 3a,b, 4,s and 6a,b have been isolated from the reaction of 2a,b with malononitrile, ethyl cyanoacetate, w-cyanoacetophenone and cyanoacetanilide, resp. The structures of the pyridones 3a,b, 4 5 and 6a,b have been confirmed from spectral data. The reaction is assumed to proceed via addition to the activated double bond followed by cyclisation of the intermediately formed Michael adducts (cf. Chart 1).Similarly, 2b reacted with ethyl acetoacetate and acetylacetone under the same conditions to yield the pyran derivatives 7 and 8, resp.In a similar manner, we report here a new procedure for the synthesis of the pyrazolo [4,3-b]pyran 10 via the reaction of the a-functional cinnamonitrile derivative 2b with 2-pyrazolin-5-ones. The synthesised compounds are interesting in biological activity studies. Thus, it has been found that the a-cyanocinnamonitrile derivative 2b reacts with 1,3-dimethy1-2-pyrazolin-5-one (9) to yield an 1:l adduct. Four possible structures were considered (cf. structures lO-W, Chart2). Structures 12 and 13 were readily excluded based on 'H-NMR spectra which revealed the absence of signals for pyrazole H-4. However, spectral data seemed of little help in discriminating structures 10 and 11. Structure 10 could be established for the reaction product based on the identity of the 03654233/83/101M)822 $ M.50/0 8 Verlag