A Convenient Route to 5,6-Diphenyl-5,6-dihydro-uracils

Diphenylcyclopropenone(1) reacts with a variety of thiopseudoureas to eventually afford dihydrouracils     

Synthese von 5,6-Epimino-5,6-dihydro-β-jonon

Synthesis of 5,6-Ephnino-5,6-dihydro-β-ionone In order to synthesize the title compound 5 the 2-azidoalcohols 3 and 4 were treated with various nucleophilic phosphorus compounds. It was found that the course of the reaction depends strongly upon the kind of nucleophilic phosphorus derivative used.     

Preparation of enantiomerically pure 5,6-dihydroxy-isobenzofuranones and 5,6-dihydroxy-4,7-methano-isobenzofuranones

Summary Optically pure available lactones1 and5 were diastereoselectively oxidised tocis-diols2 and6 by KMnO₄ and to epoxides3 and7 by 3-chloroperoxybenzoic acid. Epoxide3 was cleaved totrans-diol4, whereas hydrolysis of7 afforded tricyclic carboxylic acid8. Optic ally puredihydroxylactones2,4, and6 are valuable models for structure determination of the antimicrobial garlic component garlicin.

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Synthese enantiomerenreiner 5,6-Dihydroxy-isobenzofuranone und 5,6-Dihydroxy-4,7-methano-isobenzofuranone

Zusammenfassung Die in enatiomerenreiner Form verfügbaren Lactone1 und5 wurden durch diastereoselektive Oxidation mit KMnO₄ zu dencis-Diolen2 und6 bzw. mit 3-Chlorperoxybenzoesäure zu den Epoxiden3 und7 umgesetzt. Das Epoxid3 liefert bei der Hydrolyse dastrans-Diol4, während aus7 die tricyclische Carbonsäure8 entsteht. Die optisch reinen Dihydroxylactone2,4 und6 können als Vergleichssubstanzen zur Strukturaufklärung des antimikrobiellen Knoblauchinhaltsstoffes Garlicin dienen.

     

5,6-二甲氧基吲哚的合成

利用商业可购买的3,4-二甲氧基苯甲醛为原料,与叠氮乙酸乙酯缩合得到叠氮基肉桂酸甲酯;再经过分子内环化获得5,6-二甲氧基吲哚甲酸酯,通过水解获得5,6-二甲氧基吲哚-2-甲酸,经过脱羧后合成5,6-二甲氧基吲哚,产品总收率为49%。探讨了浓度,反应温度,反应时间三种参数对该路线中环化反应收率的影响。该合成路线具有原料简单、路线短,可操作性强,合成效率高等优点。所有化合物均采用IR,NMR,MS等多种谱学技术进行了结构表征。     

5,6-didehydro-10-methylbenzocyclooctene

Treatment of 5-bromo-10-methylbenzocyclooctene (11) with potassium tert-butoxide gave 5-methyl-9-tert-butoxybenzocyclooctene (14), presumably via 5,6-didehydro-10-methylbenzocyclooctene (13). The cyclic acetylene (13) could be trapped by reaction with 1,3-diphenylisobenzofuran to give the adduct (15).     

Interaction between Non-Conjugated Chromophores: 5,6-Dimethylidene-exo-2-norborneol, 5,6-Dimethylidene-exo,exo-2,3-norbornanediol and 5,6-Dimethylidene-2-norbornanone

Preparation of the title compounds 11 , 12 and 13 is described. Preliminary kinetic results indicate that the hydroxyl substituents in 11 and 12 have a very small retardation effect on the Diels-Alder reactivity of 2,3-dimethylidene-norbornane. The keto group in 13 exerts a larger retardation effect, although it is much smaller than the retardation effect introduced by an exo-5,6-epoxide ring in 2,3-dimethylidene-norbornane.     

Synthesis of 5,6-carbonyldioxyindole,a melanogenic cyclic carbonate ester of 5,6-dihydroxyindole

5,6-Carbonyldioxyindole ( 4 ), a melanogenic derivative of 5,6-dihydroxyindole ( 1 ), was synthesized by a procedure starting with 3,4-methylenedioxycinnamic acid ( 5 ). Compound 4 is a stable crystalline solid which is readily hydrolyzed to 1 , a key intermediate on the biosynthetic pathway from tyrosine to melanin.     

Spectrophotometric determination of the apparent ionization exponents of 5,6-dihydrouracil and 5,6-dihydrothymine

The spectrophotometric determination of the apparent ionization exponents of 5,6-dihydrouracil (DHU) and 5,6-dihydrothymine (DHT) is described. The values of pK′_α at 37°C and ionic strength of 0.16 are 11.42 for DHU and 11.57 for DHT.     

A heterocyclic arene oxide. 5,6-Diphenylbenz[c]acridine 5,6-oxide

The first synthesis of a benz[c]acridine 5,6-oxide is described. Treatment of 5,6-benz[c]-acridinequinone with phenylmagnesium bromide results in the formation of a trans-diol, which gives the title compound upon dehydration with dimethylformamide dimethylacetal. In sulfuric acid, the epoxide rearranges mainly into 6,6-diphenyl-5-benz[c]acridone.     

Thermal Rearrangement of 5,6-Epimino-5,6-dihydro-β-ionone and Derivatives

Thermolysis of 5,6-epimino-5,6-dihydro-β-ionone ( 1 ) and its N-methyl derivative ( 2 ) leads to their monocyclic isomers 6 and 10 , respectively, presumably due to a direct [1,5]-H shift; on prolonged heating, these isomers are converted easily into pyrrole derivatives. In contrast, the thermoisomer 12 resulting from 5,6-(N-methoxycarbonyl)epimino-5,6-dihydro-β-ionone ( 3 ) by the same mechanism, does not undergo further ring transformation, but equilibrates with its more stable tautomer 13 .