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Sulphur containing heterocycles

Sections on the synthesis of sulphur-containing heterocycles have [Pg.479]

The use of lasers in photochemistry is far from common, but Bertaina et al. have found that pulsing a mixture of Sq and cyclo- [Pg.479]

Whether this hails the start of a general method depends on whether the yield (c. 1%) can be improved and the scope extended further studies are underway. In a more familiar vein the intramolecular variant of the previously reported [2+2] photocycloaddition of olefins to thioamides has been published where the alkenyl thio- [Pg.479]

The thiol group has not seen regular use as a terminating group in polyene cyclization, but now Saito et al. have shown that it behaves quite satisfactorily giving tetrahydrothlophene annulated [Pg.479]

The McMurray coupling of ketones has proved to be a very useful method of carbocyclic synthesis and this has now been extended to the synthesis of sulphur heterocycles. Thus treatment of the diketo-sulphides (97) with low-valent Ti (from TiCl and Zn) at low [Pg.482]

Most methods for the synthesis of thiirans use epoxides as the starting materials but yields are generally low. Takido et al have described a new approach to this conversion using [Pg.565]

Thiocarbonyl ylide addition to olefins features as the most popular approach to tetrahydrothiophenes published this year. The parent thiocarbonyl ylide (59) can be generated from chloromethyl trimethylsilylmethyl sulphide with caesium fluoride, and the ylide [Pg.565]

Intramolecular Diels-Alder reaction of the vinyl sulphide diene (62) furnishes the corresponding fused ring tetrahydrothiophene as a mixture of the four possible diastereoisomers, where the major isomers (63) and (64) arise from the stereocontrol exerted by the silyloxy substituent.50 [Pg.565]

The unmasking of 1,3-dithianes by electrolytic oxidation, to generate ketones, has been developed into a synthesis of 1,2-dithiolene 1-oxides. The method requires controlled [Pg.565]

The synthesis of heterocycles containing more than one sulphur 64 [Pg.568]


Examples of the formation of sulphur containing heterocycles by similar transformations are quite rare. The palladium catalysed ring closure of S-propargyl-2-iodophenylmercaptane in the presence of formic acid and an amine-base, analogously to phenols and anilines, led to the formation of the partially reduced benzothiophene skeleton, bearing a 3-methylydene function (3.32.),40... [Pg.41]

Fuchigami et al. have also studied the anodic fluorination of sulphur-containing heterocycles. [Pg.206]

C18 Reversed phases are not necessarily limited to polycyclic and halogenated (or nitrated) hydrocarbons, but can be used for a number of oxygen-, nitrogen- and sulphur- containing heterocyclic compounds in a similar way to that used in reversed-phase chromatography. In this context, ref. 185 describes the separation of compounds of this category. A plethora of similar separations can be found in the Section devoted... [Pg.358]

Unlike our initial imine disconnection which is restricted to nitrogen heterocycles (with one or two specific exceptions such as pyrylium salts, see Chapter 9), the heteroatom in the enamine or enamine-like disconnection could be divalent. Therefore this disconnection is also applicable to oxygen-and sulphur-containing heterocycles, typified by 1.24 and 1.25. [Pg.5]

Project A involves the synthesis of novel biologically active materials for testing in the preservation of the latex used in the manufacture of paint. From past experience, it is known that the chemicals that are likely to be active in this environment will be those based on heterocycles containing sulphur. Therefore for this Project the particular Skill Requirement is the ability to design and synthesise sulphur-containing heterocycles that will show bioactivity in this industrial outlet. The two people who will be required for this task are available in the cur-... [Pg.17]

Sulphur, or sulphur-containing heterocyclics induce the formation of cokes of small sized optical texture (22) Mochida et al. (75) examined the carbonization behaviour, in the presence of aluminium chlorides, of diphenyl sulphide, thioxanthene and thianthrene,... [Pg.25]

A number of examples of photocycloaddition to sulphur-containing heterocycles have been reported. 2,3-Dichlorobenzo(b]thiophene (226) undergoes [ 2 + 2] benzophenone-sensitized photoaddition to vinyl bromide to give the stereoisomeric adducts (227). A potentially more useful cycloaddition has been described for 4-methoxy-l-thiocoumarin (228) which with isobutene, for example, affords the adduct (229). The structures assigned to adducts of... [Pg.426]

The sulphur-containing heterocycles (38) both undergo preferential reactions at the phosphorus atom with primary and secondary amines (including silylamines). It is interesting to note that the monoamino-derivatives were obtained on reaction with ammonia, whereas only diaraino-derivatives can be obtained from a similar reaction with NaPsCIg (c/. ref. 61). By contrast, (38 ... [Pg.198]

In general, Lawesson s reagent (and, in principle, other dithioxophosphorane dimers) is a powerful agent for simple thiations at both carbonyl and phosphoryl functions, for the preparation of sulphur- and of phosphorus-sulphur-containing heterocyclic compounds (these last being fundamentally derivatives of 4-methoxyphenylphosphono(di, tri)thioic acids and for the coupling of acids and amides, particularly in peptide synthesis. [Pg.480]

MO Calculations.—An increasing interest in theoretical calculations on sulphur-containing heterocycles can be noted. Dewar has used his... [Pg.361]

The interaction of enamines with sulphur in conjunction with carbon disulphide, isocyanates, or isothiocyanates results in the production of sulphur-containing heterocyclics. Cyanamide has now been shown to participate in this reaction. Treatment of enamines of type (24) with sulphur and cyanamide at room temperature in ethanol produces a range of 2-aminothiazoles (27) in 30—70% yield no catalyst is required. Initial formation of the thiolated intermediate (25) is probably followed by addition of cyanamide, yielding (26) elimination of amine finally produces the observed thiazoles (27). Since AW-dialkylcyanamides do not undergo this reaction, cyanamide may react as the tautomeric carbodi-imide. An actual example of the reaction employing the enamine derived from cyclohexanone and morpholine is also shown [(28) - (29)]. ... [Pg.590]

Another important sulphur-containing heterocyclic ring is that of 6 8-dithio- -octanoic acid otherwise known as thioctic or a-lipoic acid. [Pg.47]

Certain hydroboration reactions which are slow under normal conditions due to their heterogeneous nature proceed much faster under the effects of ultrasound. Several acyclic and cyclic trienes have been hydroborated with borane or triethylamineborane in THF and the stereochemistry of the products investigated. A systematic study of the hydroboration of representative heterocyclic olefins with four different reagents has been undertaken in order to establish optimum conditions for the reactions. This study has been followed by an investigation into the relative rates of reaction of 9-BBN with oxygen and sulphur containing heterocyclic olefins. ... [Pg.24]

Two novel nitrogen-sulphur-containing heterocycles [Le. (384) and (385)] have been described this... [Pg.363]

Sulphur-containing Heterocycles Three- and Four-membered Rings Five-, Six-, and Seven-membered Rings... [Pg.486]

Oxygen and Sulphur-containing Heterocycles.—Dittmer and Nelsen have improved the yield of the known benzo[/>]thiete-1,1-dioxide (281) which was prepared in six steps from (280) thermolysis of (281) gave the sultine (282). Improved... [Pg.265]


See other pages where Sulphur containing heterocycles is mentioned: [Pg.76]    [Pg.92]    [Pg.373]    [Pg.142]    [Pg.196]    [Pg.58]    [Pg.615]    [Pg.565]    [Pg.758]    [Pg.348]    [Pg.348]    [Pg.349]    [Pg.350]    [Pg.351]    [Pg.352]    [Pg.353]    [Pg.479]    [Pg.195]    [Pg.10]    [Pg.301]    [Pg.392]    [Pg.346]    [Pg.348]    [Pg.6]    [Pg.388]    [Pg.220]    [Pg.277]   
See also in sourсe #XX -- [ Pg.345 ]

See also in sourсe #XX -- [ Pg.58 ]




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Heterocycles Containing Nitrogen, Oxygen, and Sulphur

Heterocycles containing

Heterocycles containing One Sulphur Atom

Heterocycles containing Two Sulphur Atoms

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