Studies on quinones. VIII. The application of michael adducts from 2-hydroxy-1,4-naphthoquinones for the preparation of dihydronaphthopyrandiones

Dihydronaphthopyran-5,10-diones 7,13, 16 and their corresponding dihydronaphthopyran-5,6-diones 8, 14,17 have been obtained starting from Michael adducts of 2-hydroxy- and 2-hydroxy-7-methoxy-1,4-naph-thoquinone ( 1, 9 ). An efficient synthesis of hydroxyhydrolapachol ( 4 ) employing 2-hydroxy-3-(3-oxobutyl)-1,4-naphthoquinone ( 5 ) is described.     

Studies on quinones

Phenanthro[1, 2-c][1, 2, 5]oxadiazole-10, 11-dione (phenanthrene quinone furazan, I), like anthraquinone furazan, is capable of adding nucleophilic agents to carbon atom 4 of the carbon skeleton or to the oxygen of the carbonyl group. Thus, its reactions with thiophenol and benzenesulfinic acid, with subsequent oxidation lead, respectively, to the substituted quinones II and IV, the latter of which is converted by the action of benzenesulfinic acid into the benzenesulfonic ester V.For part IX, see [1]     

Studies on quinones

Anthra[1,2-c][1,2,5]oxadiazole-6,11-dione (I) was added to benzenesulfinic acid and thiophenol with the formation of 4-phenyl-sulfonyl- and 4-phenylmercapto-substituted hydroquinones, which on oxidation were converted into the corresponding quinones III and VII. 4-Phenylsulfonylanthra[1,2-c][1,2,5]oxadiazole-6,11-dione (III), in turn, reacted readily with benzenesulfinic acid, adding a molecule of the latter to the carbonyl oxygen atom and was converted into the O-benzenesulfonic monoester [6] (IV). Using compounds IV and hydroxynaphtho[1,2-c][1,2,5]oxadiazole (XId) the capability of the nitrogen atom of the furazan ring of participating in the formation of intramolecular hydrogen bonds was shown.     

Studies on quinones

Anthra[1,2-c]-1,2,5-oxadiazole-6,11-dione (I) readily reacts with ammonia and primary and secondary amines, being converted with a yield of about 80–83% into the corresponding 4-amino derivatives of antnra[1,2-c]-1,2,5-oxadiazole-6,11-dione(III).For part VI, see [1].     

Synthesis of optically active michael adducts via chiral enamines

Chiral enamines, obtained bySchiff base condensation from 1,3-dicarbonyl compounds and (R)-(+)-1-phenylethylamine, were found to undergo diastereoselectiveMichael reactions with ,-unsaturated carbonyl compounds. After removal of the chiral auxiliary (R)-(+)-1-phenylethylamine by hydrolysis, theMichael adducts were isolated in 59–95% optical yield.

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Synthese von optisch aktiven Michaeladdukten via chirale Enamine

Zusammenfassung Chirale Enamine, durchSchiffbasenkondensation aus 1,3-Dicarbonylverbindungen und (R)-(+)-1-Phenylethylamin erhalten, gehen mit ,-ungesättigten Carbonylverbindungen diastereoselektiveMichaelreaktionen ein. Nach hydrolytischer Abspaltung des chiralen Hilfsstoffs (R)-(+)-1-Phenylethylamin werden dieMichaeladdukte in 59–95% optischer Ausbeute isoliert.

     

17O NMR studies on polycyclic quinones,hydroxyquinones and related cyclic ketones: Models for anthracycline intercalators

The ¹⁷O chemical shifts for six cyclic ketones which serve as models for quinones, viz. cyclohex-2-enone (1), α-tetralone (2), anthrone (3), 4H-pyran-4-one (4), 1-benzopyran-4(4H)-one (5), xanth-9-enone (6), and for six quinones, viz. benzoquinone, naphthoquinone, anthraquinone, 2,5-dihydroxybenzoquinone 5,8-dihydroxynaphthoquinone and 1,4-dihydroxyanthraquinone, were measured in toluene at 90°C. A shielding effect of approximately 50 ppm per fused benzene ring was noted for the quinones and related carbocyclic ketones; however, the analogous series of heterocyclic fused ring ketones 4–6 showed only a slight fused-ring effect on the carbonyl chemical shift. A single ¹⁷O resonance was observed for 2,5-dihydroxybenzoquinone (358 ppm) and 5,8-dihydroxynaphthoquinone (283 ppm), indicating rapid proton exchange between the oxygen atoms of these compounds. However, 1,4-dihydroxyanthraquinone gave two discrete ¹⁷O signals at 441 and 87 ppm, indicating that in this case proton exchange between oxygen atoms is slow.     

Studies on quinones. Part 25. Synthetic approaches to 6,9-dioxygenated-benzazepinones

The Schmidt and Beckmann rearrangement of 3,4-dihydro-4,4-dimethyl-1(2H)-naphthalenones bearing oxygenated groups at the 5,8-positions, and some of their oximes are reported. Depending upon the structure of the substrates and the reaction conditions 4,5-dihydro-3H-naphth[1,8-cd]isoxazol, benzazepin-2-one and 5,6-dihydro-7H-tetrazolo[1,5-a][2]benzazepine derivatives were generated.     

Studies on quinones. Part 23. Synthesis of azepinones fused to quinone systems

The Diels-Alder reactions of 3,4-dihydro-5H-1-benzazepine-2,6,9-trione 1 with butadiene, cyclopentadiene, 1-(E)-trimethylsiloxybutadiene 4 , and methacrolein dimethylhydrazone are described. Cycloaddition with the unsymmetrical dienes 4 and 18 occurs regiospecifically affording 5 and 19 respectively. The structure of 5 was established through naphthazepine 13 by comparison of its ¹H nmr with model compounds. The probable course of cycloaddition with 1-azadiene 18 is analyzed considering the polarization of azadiene 18 and the behavior of quinone 1 in the reaction with 4 . Michael addition of quinone 1 with isobutenylmorpholine 23 which afforded exclusively the cyclic O,N-acetal 24 or 25 and its convertion to benzepinquinone 26 or 27 is also reported.     

Studies on C-glycosides: XII. Stereoselective synthesis of C-aryl glucosides

2,3,4,6-Tetra-O-benzyl-D-glucopyranose 1-α-(p-nitrobenzoate) reacted with aryl ethers in the presence of Lewis acid to give β-anomers stereoselectively in high yield, but reaction with 1,3-ditrimethylsilyloxybenzene gave α-anomer using BF₃·Et₂O and β-anomer using anhydrous AlCl₃ as catalyst.     

Synthesis of tetracyclic hydroxyquinones by cycloaddition reactions with dienols.

Cycloaddition of naphthazarin and derivatives to dienols, generated thermnally from benzocyclobuenol or by irradiation of 2-methylbenzaldehyde or 2-methylacetophenone, leads to tetracyclic systems related to those present in anthracycline and tetracycline antibiotics.     

Studies on polymers from cyclic dienes. XII. Cationic polymerization of spiro[2,4]hepta-4,6-diene

Polymerizations of spiro[2,4]hepta-4,6-diene were carried out with cationic initiators and Ziegler-type catalysts. This monomer polymerized very rapidly with a variety of cationic initiators, and low monomer and initiator concentrations had to be employed in order to avoid formation of crosslinked polymers. The polymer contained 1,2 and 1,4 addition units, and there was no indication of the opening of the cyclopropyl ring in the monomer unit. The following relationship was obtained: [η] = 4.5 × 10^?8M?_n^1.71. The exponential coefficient of this equation is much greater than those typical of vinyl polymers, suggesting that the polymer chain is very stiff. The polymer showed much enhanced resistance to autoxidation as compared with polycyclopentadiene, and its softening point was above 200°C. These interesting physical and chemical properties of the monomer and the polymer can be associated with their spiro structures.