氧化剂存在下吡啶叶立德与1,4,4a,8a-四氢-1,4-桥亚甲基萘-5,8-二酮的反应

在[(Py)4Co(HCrO₄)₂]存在下,吡啶叶立德、喹啉叶立德或异喹啉叶立德分别和1,4,4a,8a-四氢-1,4-桥亚甲基萘-5,8-二酮反应,一步法合成了中氮茚类多环化合物(1a～1c,2a～2b,3).该方法原料易得,反应条件容易控制,为合成这类化合物提供了新方法.     

Diels-Alder Reactions of 5,8-Ethano-5,8-dihydro-1,4-naphthoquinone with Cyclic Dienes

Diels-Alder cycloadditions of 1,3-cyclohexadiene and cyclopentadiene to π -facially dissymmetric 5,8-ethano-5,8-dihydro-1,4-naphtboquinone (1) were examined. The stereochemical outcome of the reactions, determined by a combination of chemical and spectral methods, indicates that addition of cyclic dienes to 1 occurs preferentially at the face syn to the etheno-bridge of 1. Cycloadducts 7a/7b and 8a/8b obtained from Diels-Alder reactions of 1 with cyclopentadiene and 1,3-cyclohexadiene undergo [2+2]-photocyclization to give caged compounds 9a/9b and 10a/10b , respectively. Stereoselective reduction of the enedione double bond in 7a/7b and 8a/8b with aqueous TiCl₃ in acetone affords cis-bis-bicyclic ring-fused 1,4-cyclo-hexadiones 11a/11b , and 12a/12b , respectively.     

Studies of Diastereoselectivity in Diels-Alder Reactions of (S)S-4a,5,8,8a-Tetrahydro-5,8-methane-2-(p-tolylsulfinyl)-1,4-naphtho- quinones with Cyclopentadiene

The title compounds 6 and 7 have proved to be adequate rigid models to evaluate the ability of the sulfinyl group to control the diastereoselectivity of the [4 + 2] cycloadditions of cyclopentadiene on the ene-dione moiety. The results of thermal and Lewis acid-catalyzed reactions allowed us to establish that both reactivity and endo/exo selectivity were modulated by the presence of the sulfinyl group, the endo-anti-endo or the exo-anti-endo bisadducts being obtained as major products depending on experimental conditions. The role of the association between the SOTol group and several Lewis acids (BF(3).OEt(2), Eu(fod)(3), ZnBr(2)), which shifted the conformational equilibrium around the C-S bond, was used to explain the stereochemical course of the cycloadditions mainly controlled by steric factors. The synthesis of the exo-anti-endo bisadduct 5 was described for the first time.     

Synthesis of cis- and trans-5,8-dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone

Cis- and trans-5,8-dihydroxy-5,6,7,8-tetrahydro-1,4-naphthoquinone (1a, 1b) were for the first time synthesized from 5,8-dihydroxy-1,4-naphthoquinone (naphthazazine) (6) as a starting material and racemic triol (3) was first synthesized from 7. The configuration of 1a was determined by X-ray analysis.     

One-Pot Synthesis of 2,3,4,4a,10,10a-Hexahydro-1H-phenoxazines

Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of 2,3,4,4a,10,10a-hexahydro-1H-phenoxazines by reductive cyclization of 2-(2-nitrophenoxy)cyclohexan-1-ones...     

Antioxidant activity of 5,8-dihydroxy-1,4-dihydro-1,4-methanonaphthalene

5,8-dihydroxy-1,4-dihydro-1,4-methanonaphthalene (DDMN), a substituted phenol, is synthesized by reduction of a cyclic dione, 1,4,4a,8a-tetrahydro-endo-1,4-methano-naphtha-5,8-dione (THMND). Pulse radiolysis technique has been employed to understand the nature of transient species formed on reaction of radiolytic species of water radiolysis with DDMN.^•OH radicals were observed to react with DDMN with a bimolecular rate constant of 1.5×10¹⁰ dm³ mol⁻¹ s⁻¹. Inhibition of radiation induced lipid-peroxidation by DDMN was studied in rat liver microsomes by assessing the formation of thiobarbituric acid reactive substances (TBARS). It was found to be strongly inhibitory. The results suggest that DDMN has very good antioxidant activity and may possibly emerge as a good radio-protector.     

Synthesis and properties of water-soluble 5,8-dihydroxy-1,4-naphthoquinone thioglucosides structurally related to echinochrome

Acetylated hydroxynaphthazarin di- and trithioglucosides structurally related to echinochrome were synthesized. Their deacetylation by the action of sodium methoxide in methanol and the effect of hydroxy groups on this process were studied. Water-soluble echinochrome thioglucosides were synthesized for the first time.     

A Simple Procedure for Preparing Annulated p-Benzoquinones. Improved Synthesis of 1,4-Dihydro-1,4-methanonaphthalene-5,8-dione

A simple and efficient two-step, one-pot synthesis of substituted 1,4-dihydro-1,4-methanonaphthalene-5,8-diones is reported. This synthesis, which utilizes readily available starting materials and inexpensive reagents, can be used to prepare 1a-1c in 70–90% overall yield. This procedure was extended successfully to prepare a more highly complex annulated p-benzoquinone i.e., 8.     

Periphery-modified crown ethers. Synthesis of bis-5,8-dimethoxy-1,4-methanonaphthalene-fused crown ethers

The easily accessible and multi-functionalized 5,8-dimethoxy-6,7-dihydroxy methyl-1,4-dihydro-1,4-methanonaphthalene (1) has been utilized as the basic building material to synthesize the symmetric bis-methanonaphthalene-fused crown ethers 14a-d (BMN-16-crown-4, BMN-22-crown-6, BMN-28-crown-8, and BMN-34-crown-10), that are constructed based on the connection between the α,β-bis-benzylic carbon atoms of diol 1 and oligoethylene glycols (9a-d) via two synthetic routes keyed upon the method of Williamson ether synthesis.     

1,4,4a,10b-Tetrahydro-N,N-dimethyl-4-phenanthridinamines and 1,4,4a,5,6,10b-hexahydro-N,N-dimethyl-4-phenanthridinamines

Synthetic procedures to prepare the title compounds are described. Diels-Alder cycloaddition of β-nitrostyrene derivatives 5 to N,N-dimethyl-1,3-butadien-1-amine, 6 , gave 5-aryl-N,N-dimethyl-6-nitro-2-cyclohexen-1-amines 7. Reduction of 7 with zinc in acetic acid gave the diamino derivatives 8 . Schotten-Baumann acylation of 8 gave amides 9 . Treatment of 8 with alkyl isocyanates gave the aminourea derivatives 10 . Bischler-Napieralski cyclodehydration procudure of 9 and 10 gave 1,4,4a,10b-tetrahydrophenanthridinamines 3 and N⁶-alkyl-1,4,4a,10b-tetrahydro-N⁴,N⁴-dimethyl-4,6-phenanthridinediamines 11 , respectively. Condensation of diamines 8 with aryl aldehydes under azeotropic conditions gave imines 12 which on treatment with acids yielded 6-aryl-1,4,4a,5,6,10b-hexahydro-N,N-dimethyl-4-phenanthridinamines 4 . The stereochemistry of these materials is assigned from the proton magnetic resonance studies.     

Synthesen von cis- und trans-1,2,3,4,4a, 10a-Hexahydro-1,4-benzodioxino[2,3-c]-pyridinen

Cis- and trans-1,2,3,4,4a,10a-hexahydro-1,4-benzodioxino[2,3-c]pyridines have been synthetised and their structures established by NMR.-spectroscopy.     

Research on 1,4-naphthoquinone and quinoline-5,8-quinone

A mixture of isomeric amino chloro derivatives, the structures of which were confirmed by alternative syntheses, is formed in the animation of 6,7-dichloroquinoline-5,8-quinone.     

Synthesis of water-soluble N-Acetyl-L-cysteine conjugates of naphtazarin (5,8-Dihydroxy-1,4-naphthoquinone) derivatives

Base-catalytic condensation of N-acetyl-L-cysteine with substituted naphthazarins was first obtained a series of mono-, di-, tri- and tetra-substituted S-aminoacid naphthazarin conjugates bearing alkyl (hydroxy) groups. It was shown that three- and tetra-N-acetyl-L-cysteine naphthazarin derivatives are readily soluble in water.