Maerocyelic polyether sulfide syntheses. The preparation of thia-crown-3,4, and 5 compounds

Macrocyelic polyether sulfides have been prepared by reacting an oligoethylene glycol dichloride with a dithiol or sodium sulfide in ethanol. The trivial naming system for these compounds is an extension of the trivial crown nomenclature (5). A thia prefix is used to show that sulfur atoms have replaced ether oxygen atoms in the polyether ring. The following new compounds were prepared: 1-thia-(15-crown-5) (II) 1,4-dithia-(15-crown-5) (III) 1,7-dithia-(15-crown-5) (IV) 1,4-dithia-(12-crown-4) (VII) 1,4,7-trithia-(12-crown-4) (VIII) 1-thia-(9-crown-3) (IX) and 1,4-dithia-(9-crown-3) (X). Four other previously reported maerocyelic polyether sulfides were also prepared. The symmetry of the nmr spectra of these compounds gives added evidence for the proposed ring structures.     

Macrocyclic sulfide syntheses: A review

The syntheses of various macrocyclic sulfides are reviewed. Tables containing information on hundreds of compounds are included. The types of cyclic compounds reviewed include: macrocyclic aliphatic dithioethers, macrocyclic mercaptals and mercaptoles, macrocyclic polysulfides, dithiacyclophanes, tris-bridged polythiacyclophanes, dithia[2,6]pyridinophanes, thiophene macrocycles, and macrocyclic polyether sulfides.     

Asymmetric first total syntheses and assignment of absolute configuration of oxazinin-5, oxazinin-6 and preoxazinin-7

Asymmetric first total syntheses of the unprecedented toxins oxazinin-5, oxazinin-6 and preoxazinin-7 have been achieved from a common key intermediate 18, derived from a regiocontrolled Sharpless asymmetric aminohydroxylation and oxa-Michael reaction, which in addition to confirming the structure also established the absolute configuration of the natural products. On the way an expeditious synthesis of a metabolite bursatellin was completed in 8 steps.     

含氟芳杂环化合物的研究 7:含氟氮、硫杂二苯并王冠化合物的合成

本文研究了苯环上含强吸电子基的间硝基对氯三氟甲苯1与一些含氮、氧、硫的亲核试剂作用,经桥接、还原、关环,分别合成了含氟氮杂、硫杂王冠化合10牧11;还得到含氟三氮杂庚环化合物9,并对其生成机理进行了探讨,各步产率都较高.     

3-Substituted pyridines. preparation of 3, 5-dimethylpyridine4-phenyldipyridine,and syntheses based on it

3, 5-Dimethyl-4-phenylpyridine is prepared by catalytic dehydrogenation and N-demethylation of 1, 3, 5-trimethyl-4-phenyl-Δ³-piperidine. Oxidation of the former gives 4-phenylpyridine-3, 5-dicarboxylic acid and the dimethyl ester and bis(diethylamide) of the acid are prepared. The same acid is used to prepare 4-phenylpyridine, methyl 2-azafluorenone-4-carboxylate, and also a compound assumed to be 6,14 dioxo3-azatetracyclo[9. 2. 1. 0^{5, 13}. O^7,12]tetradeca-2, 4, 7, 9, 11, 13-hexaene.     

Rapid microwave-assisted preparation of binary and ternary transition metal sulfide compounds

Transition metal chalcogenides are of interest for energy applications, including energy generation in photoelectrochemical cells and as electrodes for next-generation electrochemical energy storage. Synthetic routes for such chalcogenides typically involve extended heating at elevated temperatures for multiple weeks. We demonstrate here the feasibility of rapidly preparing select sulfide compounds in a matter of minutes, rather than weeks, using microwave-assisted heating in domestic microwaves. We report the preparations of phase pure FeS₂, CoS₂, and solid solutions thereof from the elements with only 40 min of heating. Conventional furnace and rapid microwave preparations of CuTi₂S₄ both result in a majority of the targeted phase, even with the significantly shorter heating time of 40 min for microwave methods relative to 12 days using a conventional furnace. The preparations we describe for these compounds can be extended to related structures and chemistries and thus enable rapid screening of the properties and performance of various compositions of interest for electronic, optical, and electrochemical applications.     

The preparation and some reactions of 2, 3, 5, 6-tetrachlorophenylmagnesium chloride

The reaction of pentachlorobenzene with metallic magnesium in THF at 10–15°C gives after hydrolysis 1, 2, 4, 5-tetrachlorobenzene (76%) and pentachlorobenzene (8%); after trimethylsilylation, 1, 2, 4, 5-tetrachloro-3-(trimethylsilyl)benzene (74%), pentachloro(trimethylsilyl)benzene (8%) and 1, 2, 4, 5-tetrachlorobenzene (6%); after iodination, 1, 2, 4, 5-tetrachloroiodobenzene (44%), pentachloroiodobenzene (12%) and 1, 2, 4, 5-tetrachlorobenzene (9%); and finally after carbonation, 2, 3, 5, 6-tetrachlorobenzoic acid (58%). These products indicate that in the Grignard reaction a mixture of largely 2, 3, 5, 6-tetrachlorophenylmagnesium chloride and some pentachlorophenylmagnesium chloride is formed. The formation pentachlorophenylmagnesium chloride is explained on the basis of metal—hydrogen exchange reaction between 2, 3, 5, 6-tetrachlorophenylmagnesium chloride and the unreacted pentachlorobenzene.     

Laser Raman studies on compounds 7.O4O.7 and 7.O5O.7

Laser Raman studies on two compounds of the α,ω-bis(4-alkylanilinebenzylidene -4′-oxy)alkane series were carried out in the spectral regions 1140–1220 and 1550–1650 cm^-1 as a function of temperature. Compounds 7.O4O.7 and 7.O5O.7, exhibit SmA and SmF phases. The structural differences between these liquid crystal dimers, having either an odd or an even number of carbon atoms in the spacer, are remarkably existent in the room temperature Raman spectra. The results are rationalized on the basis of the tendency of these compounds to exhibit bent shapes, and how this manifests in the odd-even effect at the molecular level assuming a semi-rigid core region of the dimeric molecule. It is found that the behaviour of the odd spacer dimer (7.O5O.7) agrees with the molecular model, whereas the even spacer dimer (7.O4O.7) behaves in a similar fashion to monomeric compounds such as the nO.m. compounds. In both cases, dynamic changes around the C=N bond have a profound effect both on the molecular shape in the different phases and on phase behaviour.     

Benzomorphan related compounds. XVII . Oxidative cyclization of N-arylethyl-6, 7-benzomorphans

The synthesis of two new bridged polycyclic systems (I and II), possessing a rigid N-arylethylbenzomorphan structure, by mercuric acetate cyclization of the corresponding seco derivatives (IV and VI, respectively) is described. The relative configuration of these compounds and the preferred indolo[2, 3-a]- or benzo[a]quin-olizidine conformation is assigned.     

High yield syntheses of stable, singly bonded Pd2(6+) compounds

A general method for the syntheses of dipalladium compounds having a singly bonded Pd26+ core and the formula R,S-cis-Pd2(C6H4PPh2)2(O2CR)2Cl2 is described. When the alkyl group in the carboxylate ligands is an electron donating group, the compounds are stable and the yields high. The Pd-Pd distances for the diamagnetic compounds with R = CF3 and CMe3 are 2.5434(4) and 2.5241(9) A, respectively. Calculations at the DFT level suggest that the electronic configuration is sigma2pi4delta2delta*2pi*4. These represent rare examples of palladium(III) compounds.     

Improved syntheses of 6-hydroxy-5-methoxy- and 5-hydroxy-6-methoxyindoles and their O-acetates,analogs of natural eumelanin precursors

Improved routes for syntheses of gram quantities of the isomeric 5,6-acetoxymethoxyindoles, and milligram amounts of the 5,6-hydroxymethoxyindoles, have been developed. They depend on regiospecific nitration of the benzyl ethers of vanillin and isovanillin as the first steps. Improved condensations of 4,5-acetoxymethoxy-2-nitrobenzaldehydes with nitromethane gave 4,5-acetoxymethoxy-2,β-dinitrostyrenes as the key intermediates to all four indoles.     

六核钴原子簇化学 3: 一些含Co~6八面体簇骼的原子簇化合物的合成、结构和电化学性质

(R~8P)~4-nCoX~n(R=Ph,Et 等;X=C,B=1,2)与Na~E~x(E=S,Se;X=1,2)在DMF或DMF/乙醇介质中反应得到了一系列六核钴的原子簇化合物Co~6(μ~3-E)~8(PR~3)~6.这些化合物含有正规的或畸变的Co~6八面簇骼.化合物可以用I~2氧化生成正一价的簇合物而不改变簇骼的几何构型,反达来,正一价的簇合物也可以被苊烯钠还生成中性的簇合物.本文还研究了这些化合物的电化学性质并提出了氧化还原反应的电子传递过程.     

Stereocontrolled syntheses of carbocyclic C-nucleosides and related compounds.

Carbocyclic 9-deazapurine nucleosides (1-4), a spiranic pyrimidone carbocyclic compound (5), and an unusual carbocyclic isonucleoside (6) were prepared as enantiomerically pure compounds via the key intermediates 10 and 21 from 1,4-gamma-ribonolactone. The key intermediate 10 was prepared by stereoselective reduction with Bu3SnH and then converted to carbocyclic C-ribonucleosides 1, 3, and 4. 2',3'-Didehydro-2',3'-dideoxycarbocyclic 9-deazainosine (2) was prepared from a 2',3'-dimesylate 17 by treatment with Li2Te followed by an acidic deprotection. The key bicyclic intermediate 21 was prepared from a diol 20 by an intramolecular cyclization using CHI3-Ph3P-imidazole and converted to the spiranic compound 5 and an olefinic nucleoside 6 by the construction of the heterocyclic moiety followed by deprotection.     

1,N6-Etheno-7-deaza-2,8-diazaadenosine: syntheses, properties and conversion to 7-deaza-2,8-diazaadenosine

1,N6-Etheno-7-deaza-2,8-diazaadenosine (4) was synthesized from 8-aza-7-deazaadenosine (6) in 64% overall yield. The starting material 6 was obtained by the direct glycosylation of 8-aza-7-deazaadenine (7) with 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-d-ribofuranose (8) (NO2 CH3, BF3 x Et2O; 77% yield). Compound 4 was transformed into 7-deaza-2,8-diazaadenosine (5). The fluorescence of compound 4 shows an emission maximum at 531 nm (phosphate buffer; pH 7.0), which is bathochromically shifted compared to 1,N(6)-etheno-2-azaadenosine (3a) (495 nm). A conformational analysis was performed in the solid state and in solution.     

N-Alkylated 4, 5, 6, 7-tetrafluoroindoles

The electrochemical reduction of 2-nitro-1-pentafluorophenylalkanols in the presence of carbonyl compounds has given hydrochlorides of secondary amino alcohols which, in the form of the free bases, have been converted by heating in dimethylformamide into N-substituted derivatives of 4, 5, 6, 7-tetrafluoroindole and its homologs.     

Synthetic studies on arene-olefin cycloadditions-VIII. Total syntheses of (±)-silphiperfol-6-ene, (±)-7 α H-silphiperfol-5-ene and (±)-7 β H-silphiperfol-5-ene

Total syntheses of (±)-silphiperfol-6-ene, (±)-7 α H-silphiperfol-5-ene and (±)-7 β H-silphiperfol-5-ene are described in which a new element of stereoinduction in arene-olefin meta cycloadditions was tested and a new method for cycloadduct transformation was developed.     

Crystal structures of two isostructural compounds: a second polymorph of dipotassium hydrogen citrate,K2HC6H5O7, and potassium rubidium hydrogen citrate,KRbHC6H5O7

The crystal structures of a new polymorph of dipotassium hydrogen citrate, 2K⁺·HC₆H₅O₇^2?, and potassium rubidium hydrogen citrate, K⁺·Rb⁺·HC₆H₅O₇^2?, have been solved and refined using laboratory powder X‐ray diffraction and optimized using density functional techniques. In the new polymorph of the dipotassium salt, KO₇ and KO₈ coordination polyhedra share corners and edges to form a three‐dimensional framework with channels parallel to the a axis and [111]. The hydrophobic methylene groups face each other in the channels. The un‐ionized carboxylic acid group forms a strong charge‐assisted hydrogen bond to the central ionized carboxylate group. The hydroxy group forms an intermolecular hydrogen bond to a different central carboxylate group. In the potassium rubidium salt, the K⁺ and Rb⁺ cations are disordered over two sites, in approximately 0.72:0.28 and 0.28:0.72 ratios. KO₈ and RbO₉ coordination polyhedra share corners and edges to form a three‐dimensional framework with channels parallel to the a axis. The un‐ionized carboxylic acid group forms a strong charge‐assisted hydrogen bond to an ionized carboxylate group. The hydroxy group forms an intermolecular hydrogen bond to the central carboxylate group. Density functional theory (DFT) calculations on the ordered cation structures suggest that interchange of K⁺ and Rb⁺ at the two cation sites changes the energy insignificantly.