4-Hydroxy-5-phenylpyrido[3,2,1-jk]carbazol-6-ones (4, 5), which were obtained from carbazoles 1 and malonates 2 or 3, were converted to reactive intermediates such as 4-chlorides 9 or 4-tosylates 10, which gave in turn 4-azido-5-phenyl derivatives 11. 5-Alkyl-4-azides 11 were not obtained in this manner; however a new one-pot azidation reaction was developed starting from 4-hydroxy derivatives 4 which gave azides 11 in good yields. 4-Azido-5-phenyl derivative 11f cyclized on thermolysis to the indole 12. The thermal behaviour of the azides 11 was studied by thermoanalytical methods (DSC).J. Heterocyclic Chem., 42, 85 (2005).Pyrido[3,2,1-jk]carbazol-6-one is part of the heterocyclic skeleton of many natural products (e.g., strychnos alkaloids such as strychninolones and brucinolones [2], picrasidin Q [3] and olivacine alkaloids [4]). It possesses the biologically interesting combination of indole and 2-pyridone structures. Moreover, some derivatives have found interest in pharmacological [5] or in dye chemistry [6]. Our interest is focused to 4-hydroxy-5-substituted pyrido[3,2,1-jk]carbazol-6-ones (4, 5) which possess 2 reactive positions: the hydroxy group at C-4, which can be substituted by various nucleophiles, and the CH-acidic proton at C-5, which reacts with a large number of electrophiles. In this contribution we want to report an improved synthesis of 4-hydroxy-5-substituted pyrido-[3,2,1-jk]carbazol-6-ones, the acetylation, tosylation and the nucleophilic exchange of the hydroxy groups.The synthesis of some 4-hydroxy-5-substituted pyrido[3,2,1-jk]carbazol-6-ones 4 is described in the literature in a few cases either by thermal condensation of malonates 2 with carbazole 1a at about 300 °C with moderate yields [7], or by thermal condensation of dichlorophenylmalonates with carbazole 1 at 260 °C with good yields [8]. We adopted the cyclocondensation methods of malonates with 1,3-dinucleophiles earlier described for quinolones and related compounds [9] for the synthesis of 4-hydroxy-5-substituted pyrido[3,2,1-jk]carbazol-6-ones 4 and 5. The first reaction step leads in a condensation reaction at about 200 °C to the monoanilides of the carbazole 1a with the malonates 2; the end of this reaction step can be easily observed by the end of ethanol evolution; further thermolysis at higher temperatures (300-350 °C) gives, by elimination of the second equivalent of ethanol, an intermediate α-oxo ketene which attacks in an electrophilic reaction the ortho-position of the aromatic ring to cyclize to the pyrido[3,2,1-jk]carbazol-6-ones 4. The yields of this reaction type are within 60-90% except with the octadecyl malonate 2j; in this case only 24% of 4j was obtained. It was also possible to carry out this reaction in one step without interruption when a 1:1 mixture of the malonate and the carbazole 1a was heated for 12 hours in refluxing diphenyl ether solution which limits the thermolysis temperature to 253 °C. The yields are within 60-80% comparable to the stepwise reaction; the workup however is easier and the purit...

Pyrido[3,2,1‐jk]carbazoles 1, synthesized from carbazoles and alkyl‐ or arylmalonates, gave regioselective electrophilic substitution reactions at position 5 such as chlorination to 5‐chloro derivatives 2, nitration to 5‐nitro compounds 3, or hydroxylation to 5‐hydroxy derivatives 4. 5‐Hydroxy compounds 4 gave on treatment with strong bases ring contraction to 5, 6 or the ring opening product 7. Exchange of the chloro group in 2 with azide or amines gave the corresponding azides 8 and the 5‐amino derivatives 9 and 10. Alkylation of 1 with benzyl chloride or allyl bromide resulted in the formation of 5‐C‐alkylated products 11 together with 4‐alkyloxy derivatives 12. J. Heterocyclic Chem., 48, 1039 (2011).

Amination of 4‐hydroxypyridocarbazolones 1 with aniline or benzylamine gave in good yields 4‐amines 3. With piperidine in a sealed tube from 4‐hydroxy‐ or 4‐chloro‐5‐alkylpyridocarbazolones 1 or 4 ring opened 1‐acylcarbazoles 5 were obtained. Only 4‐hydroxy‐5‐phenyl‐pyridocarbazolone 1d gave 4‐amines 6. Reduction of 4‐azidopyridocarbazolones 7 either by catalytic hydrogenation or in a 2‐step synthesis via phosphazenes 8 gave 4‐aminopyridocarbazolones 9. Amines 9 were also obtained from benzylamines 3 by catalytic debenzylation. A one step amination of 4‐hydroxy‐5‐phenylpyridocarbazolone 1d via debenzylation to 9d was observed by reaction with benzylammonium chloride. At elevated temperatures the highly fused 6,13b‐diazaindeno[1,2,3‐hi]chrysenone 10 was formed from 1d.

4-Chloro-or 4-tosyloxyquinolines 1 and 10 react with CH-acidic compounds such as malonates 2a,b, ethyl cyanoacetate (2c), malononitrile (2d), ethyl acetoacetate (2e), acetylacetone (2f) or dimedone (2g) under mild conditions and good yields to quinolin-4-yl substituted derivatives 3-8 and 11. With 3-phenylsulfonylquinolones 1i-k a redox reaction to 2-hydroxy-2-quinolin-4-yl-malonates 9 was observed. Amination of 3-nitroquinolinyl malonate 3f leads to malonester-amides 13 and 14. J. Heterocyclic Chem., 43, 117 (2006).Recently we could show that 3-nitroquinolin-4-yl-malonates, obtained from 4-chloro-3-nitroquinolones and malonates, give in thermal reactions either quinolinylacetates or a ringclosure reaction to isoxazolo [3,4-c] and substitution with halo-hetaryl compounds, however the latter one with poor results [2]. In this work we report on a study about the introduction of 4-quinolinyl substituents at the CH-acidic carbon of various CH-acidic compounds. Moreover, the influence of substituents in position 3 of the quinoline nucleus on this reaction was studied.The reaction of ethyl-or methyl malonates 2a,b as CHacidic compounds with various 4-chloro-or 4-tosyloxy-2-quinolones 1b-g in dimethylformamide and potassium carbonate as the base, was investigated and found to give good to excellent yields of 4-quinolinyl substituted malonates 3a-j. It was reported recently that similar 3-nitroquinolones give such malonates of type 3 only in poor yields (8-37%) at reaction temperatures of about 100 °C using sodium hydride as the base [2]. It is likely that these reaction conditions favor already the decomposition reactions we have described earlier in a few examples [1]; however, with our mild reaction conditions 3-nitroquinolinyl-malonates 3e-j were obtained in yields of 66-95%. Quinolones 1 having other electron-withdrawing groups in 3-position reacted too in excellent yields to the corresponding malonates 3: in this manner, 4-chloro-3-cyanoquinolone 1b gave with malonates 2a,b in 85-86% yield the corresponding quinolinyl-malonates 3a,b; 3-acetylquinolones 1c,d with 4-tosyloxy substituents as leaving group gave with diethyl malonate (2a) in 66-69% yield the corresponding quinolinyl-malonates 3c,d.When ethyl cyanoacetate (2c) was used as CH-acidic compound the 3-nitroquinolones 1e-g gave in excellent yields and short reaction times (3 hours compared with up to 20 hours in the malonate series [1]) the quinolinylcyanoacetates 4a-c. Malononitrile (2d) reacted with 3-nitroquinolone 1e to give a very labile compound that decomposed on work-up. Attempts to purify and identify the follow-up product were unsuccessful, but it seems from spectral data (e.g. mass of 239) that a reaction of one cyano group with the 3-nitro group of the quinolone has taken place. When the 3,4-dichloroquinolone 1h was reacted with malononitrile (2d), the expected quinolinyl-

XV) possessing two reactive positions, i.e. the hydroxy group at C-4 and the CH-acidic proton at C-5, are subjected to acetylation, tosylation as well as to nucleophilic exchange of the hydroxy groups. Cyclocondensation methods are adopted for these compounds improving their syntheses. In these reactions the first step consists of a condensation reaction, followed by thermolysis, cf. (I)→(IX). This reaction can also be carried out in one step by heating the carbazole with the malonate in diphenyl ether, cf. (I)→(III), making the work-up easier and the purity of the products better. The synthesis of the desired 5-alkylated azide derivatives from the corresponding precursors, e.g. (VI), is impossible. However, a new one-pot synthesis provides the targets, e.g. (VII), in low to moderate yields, but with excellent purity. On cyclization, (XII) affords the highly fused indolopyridocarbazolone (XIII), a hitherto unknown heterocyclic system. -(DANG, H. V.; KNOBLOCH, B.; HABIB, N. S.; KAPPE, T.; STADLBAUER*, W.; J. Heterocycl. Chem. 42 (2005) 1, 85-91; Dep. Chem., Karl-Franzens-Univ., A-8010 Graz, Austria; Eng.) -H. Hoennerscheid 28-158 2005 Fused pyridine derivatives