The Photoisomerization of 1,2,3,4,5-Pentamethyl-5-vinyl-1,3-cyclopentadiene

The title compound 1 is shown to give, both upon direct irradiation at 254 nm and upon acetophenone-sensitized photolysis at 300 nm, the syn-vinyl-pentamethylhousene 5 , which spontaneously rearranges in a [3,3]0sigmatropic process to give the bicyclo[3.2.0]heptadiene skeleton 2 . Based on the photochemical behaviour of selectively deuterated starting material, the suggestion is made that the direct photolysis produces the vinylhousene skeleton by a classic electrocyclization, whereas the sensitized reaction reaches the same target via a di-π-methane rearrangement. The bicyclo[3.2.0]heptadiene derivative 2 give pentamethylhomoprismane 3 upon prolonged irradiation at 254 nm.     

The Synthesis of Ethyl 5-Vinyl-2-Quinuclidine Carboxylate

The synthesis of the minor indolic cinchona alkaloid, cinchonexine (1), from ethyl-5-vinyl-2-quinuclidine carboxylate (2) was reported in 1958¹ but the preparation of 2 was not described until several years later². No further reports on this problem have since appeared. Since 2 was previously obtained in very poor yield from the Beckmann rearrangement of quininene oxine² a more direct approach to its preparation was initiated in order to complete the total synthesis of cinchonexine from synthetically available precursors. Maroquinine (3a) which not only has been prepared in both racemic ³ and optically active^3b forms but is also readily available from quinine⁴ was selected as the starting material fro this synthetic sequence.     

5-甲基-7-甲氧基异黄酮的合成

5-甲基-7-甲氧基异黄酮的合成;二羟基甲基脱氧安息香; 甲基甲氧基异黄酮; 二羟基甲苯; 有机合成     

Structure and Conformational Analysis of 5-Methyl-2,2-diphenyl-1,3-dioxane

Russian Journal of Organic Chemistry - The structure of 5-methyl-2,2-diphenyl-1,3-dioxane has been studied by1H and 13C NMR spectroscopy and X-ray analysis. Its molecules in crystal, as well as in...     

1,3-Dipolar Cycloaddition of 5-Substituted-1-Methyl-3-Oxidopyridiniums

5-Methoxy- and 5-dimethylamino-1-methyl-3-oxidopyridiniums were shown to give the 1,3-dipolar cycloadducts widely with methyl acrylate, acrylonitrile, N-phenylmaleimide, styrene, phenylacetylene, cyclopentadiene, cyclopentene, diethyl azodicarboxylate and singlet oxygen.     

"一锅法"合成5-甲基-4-甲酰基-己腈

以异戊醛,吗啉和丙烯腈为原料,用一锅法合成了5-甲基-4-甲酰基-己腈.通过正交试验确定了最佳的反应条件异戊醛0.1 mol,n(异戊醛)n(吗啉)n(丙烯腈)＝1.01.21.4;溶剂[V(甲醇)V(水)＝182]200 mL·mol-1(以烯胺计),于70 ℃反应15 h(第2步),产率96.06%,产物易分离和纯化.     

Characteristics of the Synthesis of Substituted and Condensed 2-Methyl-1,3-diazoles

Condensation of aliphatic and carbocyclic α-bromo ketones with thioacetamide in ethanol usually leads to substituted or condensed 2-methyl-1,3-thiazoles. However in a number of cases the required compounds are only obtained in pyridine. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, 1244–1249, August, 2005.     

Synthesis and Stereochemistry of Substituted 1,3-Dioxa-2-silacyclohexanes: VII. Synthesis and Stereochemistry of Substituted 2-Vinyl-2-methyl-1,3-dioxa-2-silacyclohexanes

The stereochemistry of substituted 2-vinyl-2-methyl-1,3-dioxa-2-silacyclohexanes was studied by ^1Hand ^13C NMR spectroscopy. The configurational and conformational assignment of a mixture of 2-vinyl-2,4-dimethyl-1,3-dioxa-2-silacyclohexane diastereomers with various ratios of the cis and trans forms was made. The molecules of both conformers occur chiefly in the chair conformartion with equatorial location of the methyl group at the C⁴ atom. The experimental data were confirmed by AM1 and MM+ optimization of the molecular geometry.     

Oxidative Transformation of 1,3-Cyclopentadiene in a System CuBr2-Ethylene Glycol

Oxidation of 1,3-cyclopentadiene with copper(II) bromide in dimethylformamide containing ethylene glycol resulted in 1,4-dioxabicyclo-6-nonene. The kinetic parameters of the oxidation reaction were studied. In contrast to oxidation of acyclic dienes at cyclopentadiene oxidation its interaction with one molecule of CuBr₂ is an irreversible and limiting stage.     

Synthesis of 2-Methyl-5-nitroimidazol-1-yl-acetaldehyde

Pure 2-methyl-5-nitroimidazol-1-yl-acetaldehyde was synthesized by modified Swern oxidation. This compound can be utilized as reaction intermediate in the synthesis of bioreductive agents (e.g., hypoxic cell radiosensitizers, antibiotics against anaerobic organisms).     

4-甲基-5-硝基-1,2,3-连三唑的合成

以丙二酸二乙酯为原料,经水解、硝化得到关键中间体偕二硝基乙酸乙酯(2);2与乙醛、叠氮化钠缩合环化得到4-甲基-5-硝基-1,2,3-连三唑(3)。3的结构经NMR,IR和元素分析表征。初步探讨了硝化反应的反应历程,并对制备2的合成进行了工艺改进,发现以NaNO2-98%HNO3为硝化试剂的新方法,2的收率达62.1%,纯度93.1%。     

5-甲基-3-硝甲基己酸乙酯的合成

以异戊醛和膦酰乙酸三乙酯为原料,1,8-二氮杂二环［5,4,0］十一碳-7-烯(DBU)为催化剂,碘化钠为磷酸酯碳负离子稳定助剂,经Horner-Wadsworth Emmons反应合成了5-甲基-2-己烯酸乙酯(3),收率90%;仍以DBU为催化剂,3与硝基甲烷经Michael加成反应合成5-甲基-3-硝甲基己酸乙酯,收率98%,两步总收率88.2%,其结构经¹H NMR和IR确证。     

5-甲基-2(1H)吡啶酮的合成

以5-甲基-2-氨基吡啶为起始原料,通过重氮盐水解反应,合成了5-甲基-2(1H)吡啶酮,并对其合成工艺进行了研究,其结构经IR确证。     

On the Preparation of 4-Hydroxymethyl-5-Methyl-1,3-Dioxol-2-One

A practical and efficient conversion of 4-bromomethyl-5-methyl-1, 3-dioxol-2-one 1 into the corresponding carbinol 2, a useful building block for the preparation of prodrugs, is reported.     

4-甲基-5-卤代-2-噻吩甲醛和2,4-二甲基-5-卤代噻吩的合成

以3-甲基噻吩为原料,经过卤代反应、Vilsmeier甲酰化反应和Wollf L-Kishner-Huang minion反应合成了4-甲基-5-卤代-2-噻吩甲醛和2,4-二甲基-5-卤代噻吩,其结构经NMR,IR,MS和元素分析确证.     

Synthesis of 5-alkenyl-1,3-dioxanes

Cyclic acetals containing alkenyl groups were obtained from 5-methyl-5-acyl-1,3-dioxane. The 1,3-dioxane fragment does not interfere in reduction of the carbonyl group, nor in participation of the carbonyl group in Wittig and Grignard reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 37–39, January, 1991.