A General Method for the Preparation of 6-Hydroxy-4-Alkyl-Hexanals

6-Hydroxy-4-alkylhexanals are important intermediates in the synthesis of juvenile hormones and their analogs. We wish to report an economic route to these compounds which starts essentially with an easily accessible p-substituted phenol. Catalytic hydrogenation of the phenol is known ¹ to give, depending on the reaction conditions, either the corresponding cyclohexanone or the cyclohexanol. The latter is easily oxidized to the ketone. The cyclohexanone is then subjected     

Transformations of 4,5-Substituted (4S,5S)-2,2-Dimethyl-1,3-dioxolanes

(4S,5S)-4,5-Bis(hydroxymethyl)-2,2-dimethyl-1,3-dioxolane treated with trifluoromethanesulfonyl chloride in pyridine undergoes tandem substitution of one hydroxy group by a triflate group, and the other by pyridinium moiety. In neutral solvents the (4S,5S)-4,5-bis(hydroxymethyl)-2,2-dimethyl-1,3-dioxolane dilithium salt reacts with trifluoromethanesulfonyl chloride affording both triflates and chlorides and also suffers a cleavage of the dioxolane ring followed by transformations of acyclic products. A triflate cationic complex rhodium cyclooctadiene (4S,5S)-2,3-dihydroxy-1,4-bis(dimethylamino)-2,3-O-isopropylidenebutane was prepared and used as catalyst for hydrogenation of -acetamidocinnamic and itaconic acids.     

A convenient Synthesis of 6-Substituted-2,2-Dimethyl-2H-1-Benzopyrans

Various 2,2-dimethyl-6-functional-2H-1-benzopyrans were prepared via a halogen-metal exchange reaction followed by treatment with electrophiles. These 6-functionalized chromenes are important synthetic intermediates for preparation of benzopyran-based potassium channel openers.     

A General Method for the Preparation of 4-Acyl-Cyclohex-3-Enones and Their Derivatives

The metal-ammonia reduction of methoxylated aromatic compounds (the Birch reduction), followed by the acid catalysed hydrolysis of the resultant methoxycyclohexadienes, provides a convenient route to cyclohexenones but suffers from the limitation that oxygen atoms are hydrogenolysed completely from the benzylic position. This has been attributed¹ to the dianion produced by the addition of two electrons undergoing rapid cleavage to the benzylic anion and an oxide anion. It has been shown that the introduction of electron-releasing substituents such as methoxyl² or methyl³ into the 4-position of the ring gives some retention of oxygen in benzyl alcohol derivatives. However, an attempt⁴ to maintain the oxidation level of a carbonyl group by protecting 4-methoxyacetophenone as its dioxolane derivative (1) was unsuccessful since reduction gave (2) as the major product. This result has been confirmed but it would appear that the use of this particular protecting group was an unfortunate choice.     

Study of Nitrogen- and Sulfur-Containing Heterocycles. 57. Synthesis and Conversion of 4′-Substituted 5-(5-Amino-6-Pyrimidylthio)-2,2-Dimethyl-4,6-Dioxo-1,3-Dioxanes

By reaction of 4-substituted 5-amino-6-mercaptopyrimidines with 5-bromo-2,2-dimethyl-4,6-dioxo-1,3-dioxane, we have obtained 4′-substituted 5-(5-amino-6-pyrimidylthio)-2,2-dimethyl-4,6-dioxo-1,3-dioxanes. We have studied diazotization of these compounds by isoamyl nitrite. In the case of 4′-methoxy- and 4′-dimethylamino-substituted derivatives, we have obtained derivatives of novel heterocyclic systems: pyrimido[5,4-e][1,3,4]thiadiazine and pyrimido[5,4-e][1,3,4]thiadiazine-7-spiro-5′-1,3-dioxane, and in the case of the 4′-isopropylamino-substituted derivative we obtained 4-isopropyl-7-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-ylidene)-1,2,3-triazolo[5,4-d]pyrimidin-7-ylidene.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 613–623, April, 2005.     

Synthesis of Benzopyran Derivatives,XIV: New Procedure for the Preparation of 2,2-Dimethyl-2H-chromenes

2,2-Dimethyl-4-methoxychromans (1–12) have been converted into 2,2-dimethyl-2H-chromenes (13–24) in acidic media.     

Na2S2O4-Mediated Cyclocondensations of 2,2'-Disulfanediyldianilines with Aldehydes: A Facile and Inexpensive Method for the Synthesis of 2-Substituted Benzothiazoles

A facile and inexpensive method for the synthesis of 2‐substituted benzothiazoles has been developed by Na₂S₂O₄‐mediated cyclocondensations of 2,2′‐disulfanediyldianilines with aldehydes. In the presence of Na₂S₂O₄ and 4 Å molecular sieves, a variety of 2‐substituted benzothiazoles were obtained from the reaction of 2,2′‐disulfanediyldianilines with aldehydes in moderate to high yields.     

A Practical General Method for the Preparation of Long Acenes

The field of long acenes, the narrowest of the zig-zag graphene nanoribbons, has been an area of significant interest in the past decade because of its potential applications in organic electronics, spintronics and plasmonics. However the low solubility and high reactivity of these compounds has so far hindered their preparation on large scales. We report here a concise strategy for the synthesis of higher acenes through Diels–Alder condensation of arynes with a protected tetraene ketone. After deprotection by cleavage of the ketal, the obtained monoketone precursors cleanly yield the corresponding acenes through quantitative cheletropic thermal decarbonylation in the solid state, at moderate temperatures of 155 to 205 °C. This approach allows the preparation of heptacene, benzo[a]hexacene, cis- and trans-dibenzopentacene and offers a valuable new method for the synthesis of even larger acenes.     

A Preparative Method for Blocking of Ketone Group in 2,2-Dimethyl-3-(2-Oxopropyl)-Cis-Cyclopropaneacetaldehyde

An efficient three-step procedure for protection of ketone group in 2,2-dimethyl-3-/2-oxopropyl/-cis-cyclopropaneacet-aldehyde 1 is described.     

An Improved One-Pot Method for the Preparation of 2-Substituted 1H-Perimidines

2-substituted 1H-perimidines are readily prepared, in high yields, by refluxing a mixture of sodium pyrosulfite, an aldehyde, and 1, 8-diaminonaphthalene in aqueous ethanol or N, N-dimethylformamide. The method is of wide applicability except from araldehydes bearing a strong electron-withdrawing group (-CN, -NO₂).     

Synthesis and Some Transformations of (2,2-Dimethyl-4-propyltetrahydro-2H-pyran-4-yl)acetonitrile

Russian Journal of General Chemistry - Removal of the ethoxycarbonyl group in ethyl cyano-(2,2-dimethyl-4-propyltetrahydro-2H-pyran-4 -yl)acetate afforded the corresponding...     

Synthesis, Crystal Structure and Antiproliferative Activity of 2,2-Dimethyl-4-oxochroman-3-ylmorpholine-4-carbodithioate

The crystal structure of the new title compound 2,2-dimethyl-4-oxochroman-3-ylmorpholine-4-carbodithioate(C16H19NO3S2,Mr = 337.44) has been prepared and determined by single-crystal X-ray diffraction.The crystal is of triclinic,space group P1 with a = 9.5518(7),b = 9.7172(7),c = 11.0220(8),α = 67.08(1),β = 74.66(1),= 61.31(1)°,V = 822.72(10)3,Z = 2,Dc = 1.362 g/cm3,F(000) = 356,μ = 0.092 mm-1,MoKa radiation(λ = 0.71073),R = 0.0515 and wR = 0.1389 for 2623 observed reflections with I > 2(I).X-ray diffraction analysis reveals that the chroman ring adopts a half-chair conformation while the morpholine ring shows a chair conformation.Intramolecular and intermolecular C-H···S and C-H···O hydrogen bonds together with π-π interations are found in the structure.The result of MTT assay shows the title compound displays good antiproliferative activity against two human cancer cell lines.     

Improved Method for the Preparation of 1,1-Dimethyl-3-arylureas Using Chlorocarbonylsulfenyl Chloride

A convenient procedure for preparing some arylureas having herbicidal properties is reported. The method has two steps: (1) reaction of arylamine with chlorocarbonylsulfenyl chloride in the presence of nonpolar solvent to produce aryl carbonylsulfenyl chloride and (2) reaction with dimethylamine in a two-phase reaction catalysed by phase-transfer catalyst to produce the corresponding aryl ureas.     

A Simple Strategy for the Preparation of 6-Substituted 3H-Benzoxazol-2-ones and 3H-Benzothiazol-2-ones

The double metallation of 6-bromo-3H-benzothiazol-2-one and 6-bromo-3H-benzoxazol-2-one with methyl magnesium bromide and alkyllithium bases is described. Alkylation with a variety of electrophiles occurs at the 6-position of the heterocycles in good yields.      

A Novel and Efficient Synthesis of 6-Alkyl-7-alkyloxy-2,2-dimethyl-Chromans

A series of 6-alkyI-7-alkyloxy-2,2-dimethyl-chroman was prepared via a novel pathway from the corresponding 7-alkyloxy-2,2-dimethyl-4-chromanones.     

一种高效的双烯酮替代物——2,2-二甲基-1,3-二噁环己-4-烯-6-酮类化合物的合成

2,2-二甲基-1,3-二噁环己-4-烯-6-酮类化合物2可以代替双烯酮, 定量地和亲核试剂发生反应, 并且本身安全无毒, 化学性质稳定, 成本低廉, 是一类高效的双烯酮替代物. 本文对2的合成方法进行了研究, 采用简便易行的方法成功地合成了一系列双烯酮的替代物.     

2,3-Dimethyl-7-methoxy-6-aminoindole in the synthesis of linear pyrroloquinolines

The possibility of using 2,3-dimethyl-7-methoxy-6-aminoindole for the production of pyrroloquinolines was studied. It was established that the methoxy group at position 7 activates the closure of the pyridine ring with the formation of linearly fused pyrroloquinolines in the Combe reaction, under the conditions of the Vilsmeier reaction and of the thermal cyclization of aminocrotonate, and in the high-temperature cyclization of aminomethylenemalonate.M. E. Evsev'ev Mordvinian State Pedagogical Institute, Saransk. M. V. Lomonosov Moscow State University, Moscow. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 75–79, January, 1997.     

7,7-二甲基-2-对溴苯基-4-苯基-5-氧代-1,4,5,6,7,8-六氢化-6H-喹啉的合成及晶体结构

标题化合物C23H22BrNO是由1-(4-溴苯基)-3-苯基-2-丙烯-1-酮与5,5-二甲基-1, 3-环己二酮在N, N-二甲基甲酰胺(DMF)中在NH4OAc催化下反应而得。结构通过单晶X-射线衍射分析确定,其晶体属于单斜晶系,空间群C2/C, a = 19.678(4),b = 13.571(2),c = 17.311(3) 牛琤 = 118.74(1),Mr = 408.33, V = 4055(1) ?,Dc = 1.338 g/cm3, Z = 8, m (MoKa) = 2.038 mm-1, F(000) = 1680, R = 0.0539,wR = 0.1369。X-衍射分析表明,六元环C(10)C(13)C(16)C(17)采用半椅式构象:原子C(10),C(11),C(12),C(16)和C(17)在同一个平面内,而原子C(13)远离平面为0.3282 牛闷矫嬗?个苯环的夹角分别为41.09, 81.97,2个苯环的夹角为75.87。另外在晶体结构中,存在1个分子间氢键。