Pyrano quinolines

Kamal A, Prasad BR, Ramana AV, Babu AH, Reddy KS (2004) FeCl3-NaI mediated reactions of aryl azides with 3,4-dihydro-2 //-pyran a convenient synthesis of pyrano-quinolines. Tetrahedron Lett 45 3507-3509... 

Similar oxidation of the methoxyquinolone LIX gave a water-soluble product, isolated as the perchlorate, which was identified as ( )-0-methylbalfourodinium (LV) perchlorate. When the norquiriolone LX was treated with peroxylauric acid, a mixture of the furo- and pyrano-quinolines LXVI and LXVII was obtained heating of the latter with methyl iodide furnished ( + )-isobalfourodine, while the former similarly gave ( + )-balfourodine (135). 

The intermediate 94 undergoes thennal cyclisation to give the angular pyrano-quinoline 95. 

During the last decade, new alkaloids of this type have been isolated, methods of asymmetric synthesis have been developed, the absolute stereochemistry of a number of alkaloids has been established, and the mechanisms of certain rearrangement reactions of furo- and pyrano-quinoline alkaloids of the group have been studied. Additional pyrano-quinolines of the flindersine type have been discovered, and new methods of synthesis have been developed. Isopropyldihydrofuroquinoline alkaloids without a hydroxy group in the side chain are characteristic components of Lunasia species, but not much new work on this group has appeared recently. 

Flindersine (141) has been known for many years and provides an intriguing exception to the general experience that furo- and pyrano-quinoline alkaloids have a linear arrangement of the three rings. During the... 

CN 9-ethyl-6,9-dihydro-4,6-dioxo-10-propyl-4/i/-pyrano[3,2-g]quinoline-2,8rdicarboxylic acid disodium salt... 

CN 5,6-dihydro-7,8-dimethyl-4,5-dioxo-4//-pyrano[3,2-c]quinoline-2-carboxylic acid 3-methylbutyl ester... 

A one-pot synthesis of pyrano[3,2-c]quinolin-2,5(<5/7)-dione 107 was reported through the condensation reaction of chlorocarbonyl ketenes 108 with 4-hydroxyquinolin-2(l//)-ones 109. This simple procedure was shown to be a convenient synthesis of pharmacologically active compounds in high yields <06S435>. 

JOC6503>, and new pyridazino-psoralens 15 were prepared via a furan ring expansion reaction <05T4805>. The reaction of 3-acetylcoumarins with alloxan followed by NH2NH2 easily produced 3-(2-oxo-2//-chromen-3-yl)-6//,8//-pyrimido[4,5-c]pyridazine-5,7-diones <05JHC1223>. Furano- and pyrano[2,3-c]pyridazines 17 and 18a,b as well as substituted quinolines were conveniently prepared from pyridazinone 16 and vinyl- and allyltriphenyl-phosphonium salts <05HAC56>. 

INAC reactions have also led to enantioselective syntheses of key intermediates in the synthesis of antibiotic l 3-Methylcarbapenem (724), to optically pure derivatives of tetrahydropyrano[2,3] cyclohexane (725a) to novel terahydro-isoxazolo-fused pyrano 2,3-/ quinolines (725b) and to a novel heterocyclic system, isoxazolo[3,4-d]thieno[2,3-b]pyridine (Scheme 2.229) (221). 

The cyclization of N-(8-isopropyl-7-benzopyranyl)aminomethylene-malonate (649) in boiling Dowtherm A for 1 hr afforded pyrano[3,2-g]-quinoline-2,7-decarboxylate (650) in 18% yield (80GEP2943658). 

Pyrano[3,2-/]quinoline-9-carboxylate (915) was obtained in 93% yield by the thermal cyclization of 6-coumarinylaminomethylenemalonate (914) in boiling Dowtherm A for 10 min (67USP3313818). 

Chloroquinolines are reactive groupings due to electron-deficient carbon to which the halogen is attached. This carbon is electron-deficient due to the combined electron-withdrawing effects of the chlorine substituent and the quinoline nitrogen. The electrophilic carbon is thus able to react readily with nucleophiles present in the body. The impact of this grouping on a molecule is illustrated by 6-chloro-4-oxo-10-propyl-4H-pyrano[3,2-g]quinoline-2,8-dicarboxylate (Figure 8.28). In contrast to many related compounds (chromone-carboxylates) lacking the chloroquinoline, 6-chloro-4-oxo-10-propyl-4H-pyrano[3,2-g]quinoline-2,8-dicarboxylate is excreted as a... 

N-Methyl-4-hydroxy-2-quinolone 183 in a three-component reaction gives spiro pyrano[3,2-c]qionoline-2-ones (02MI2), but indolones 213 with 4-hydroxy-6-methyl-2-pyridone 177 react in a complicated way (97BCJ1625). Ethoxycarbonyl-methylene indolone (Z = COOEt) forms pyrans 224, while dicyano analogs (Z = CN) yield substituted quinoline 225 (Scheme 85). 

DMAD get thermally converted to quinolones (66), through a Cope rearrangement. These quinolones give rise to tricyclic heteroaromatic compounds, namely, pyrano[3,4-6]quinoline-l,5-diones (67) and furo-[3,2-c]quinolines (68), depending on the reaction conditions (Scheme... 

Pyrano-fused heterocycles, namely pyrano[3,2-f]quinoline-2,5(6//)-diones, pyrano[3,2-f]benzopyran-2,5(6//)-dione, and pyrano[3,2-f]pyridine-2,5(67T)-diones, have been efficiently prepared by the condensation of 4-hydroxy-2-(l//)-quinolines, 4-hydroxycoumarin, or 4-hydroxy-(17/)-pyridone with a-acetyl-y-butyrolactone or the sodium salt of a-formyl-y-butyro-lactone in the presence of ammonium acetate <1999JHC467>. 

Pyrazino[f]quinoxaline Pyrazino[2,3-g]quinoxaline 4H,6H-Pyrano[3,2-g]chromene Pyrido[3,2-g]quinoline 1 H-Cyclopenta[1,2-b 4,3-b ]dipyridine Diazafluorenes... 

Chemical Name (l,4 -Bipiperidine)-l -carboxylic acid, (4S)-3,4,12,14-tetrahydro-4,ll-diethyl-4-hydroxy-3,4-dioxo-lH-pyrano(3, 4 6,7) indolizino[l,2-b]quinolin-9-yl ester, monohydrochloride... 

Dioxo-10-propyl-4H,6H-pyrano[3,2-]quinoline-2,8-dicarbxylic acid disodium salt was prepared in 8 steps... 

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