5,6-Bis- methylen

The formation of desaurins from ketones, carbon disulfide, and base 1275,1281,1282,1285-1290 believed to involve nucleophilic attack on a thioketene by the dianion of a 1,1-dimercaptoalkene, as shown for the synthesis of 572. Related syntheses involve the use of thiophosgene instead of carbon disulfide and the use of diazoalkanes or phosphonium and sulfonium ylides instead of a ketone and base. Treatment of perfluoroiso-butylene with fluoride ion and elemental sulfur in a dipolar, aprotic solvent ° °° or with sources of anionic sulfur (potassium sulfide, sodium hydrosulfide,potassium thiocyanate,sodium thiosulfate, dithiocarbamate salts, dithiophosphate salts ) give the dimer (573) of bis(trifIuoromethyl)-thioketene. Similarly, other 2,4-bis(methylene)-l,4-dithietanes are obtained by treating 2,2-dichlorovinyl ketones with anionic sulfur re-... 

Salts of 1,1-dimercaptoalkenes can be dimerized to 2,4-bis(methylene)-l,3-dithietanes with the formal loss of hydrogen sulfide by treatment with electrophilic... 

The most common reaction of 2,4-bis-(methylene)-l,3-dithietanes with nucleophiles involves an apparent Michael addition to an electron-deficient double bond followed by ring-opening. Further reactions may ensue depending on the functional groups present. The reactions of 578 have been extensively investigated. Reactions have been reported with ethoxide ion and thiolate ions, ammonia and amines " " - (e.g., the formation of 579), hydra-... 

Although no preparatively useful metal-catalyzed [3-F 2]-cycloaddition reactions involving ketenes have been developed due to the pronounced [2-F2]-cycloaddition reactivity of this substrate vide supra), ketene derivatives, e.g. ketenimines, are much less prone to undergo [2 + 2] cycloadditions, so that [3-1-2] cycloaddition can successfully compete. However, instead of the primarily expected 2,4-bis(methylene)pyrrolidines or a-methylene-d -pyrrolines, substituted pyrroles are formed whenever double-hond isomerization is possible. For example, such a reaction smoothly proceeds with the parent MCP (4) and iV-phenyldiphenylketenimine (19) which provides 2-(diphenylmethyl)-4-methyl-l-phenylpyrrole (20) in 96% yield. 

Selenium Derivatives.—Pyrolysis of 1,2,3-selenadiazoles at 500-600 °C gives 2,4-bis(methylene)-l,3-diselenetans. Treatment of divinyl sulphone with selenium tetrabromide gave a compound that was claimed to be (125). ... 

Diphosphitylation of 2,4-0-methylene-D-glucitol (8) with phosphorus trichloride in dioxane gave 1,3 5,6-bis- 0-(chlorophosphitc) 9 (99.5%). Its amination with diethyla-mine in benzene-diethyl ether afforded the corresponding bis-amidophosphites 10. Their reaction with sulfur afforded three P-diastereomers of cyclic thiophosphate 11 in 24.8, 4.8, and 19.5% yields (Scheme 4) [19],... 

A Cu2+ containing linear polymer [77] exhibiting smectogenic behaviour is obtained by a polycondensation technique (Fig. 27). A homologous set of polycondensates of 4,4 -[l,12 dodecanediyl bisfoxy)] bis benzoic acid with bis[AT-[[2,4 dihydrophenyl]methylene]-alkylamino] Cu(II) exhibits monotropic liquid crystalline behaviour with 4—13 carbon atoms in the alkylamino group [78]. 

The photo-induced electron transfer of l,4-bis(methylene)cyclohexane in acetonitrile-methanol solution with 1,4-dicyanobenzene (DCB) affords two products, both consistent with nucleophilic attack on the radical cation followed by reduction and protonation or by combination with DCB ).63 In the absence of a nucleophile, the product mixture is highly complex, as is the case under electro-oxidative conditions. Under UV irradiation, /nmv-stilbene undergoes dimerization and oxygenation (to benzaldehyde) by a single-electron mechanism in the presence of a sensitizer such as 2,4,6-triphenylpyrilium tetrafluoroborate (TPT).64 This reaction was found to yield a similar product mixture with the sulfur analogue of TPT and their relative merits as well as electrochemical and photophysical properties are discussed. 

At that time, our coatings were made in Towanda with methylene chloride as solvent, but our custom coating was done with butanone and isopropyl alcohol. The samples of TCTM-HABI had good solubility in this solvent pair. When Green precipitated the product from the oxidation of the 2,4-bis(2-chlorophenyl)-5-(3,4-dimethoxyphenyl)imidazole, he made a startling discovery. Some of it went into solution in the ketone solvent, but most did not. What did... 

Fig. 2. Temperature dependent H-NMR spectrum (60 MHz, toluene-dg) of [s-cis-T/ -l,2,5,6-tetramethyl-3,4-bis(methylene)-tricyclo[3.1.0.0 ]hexane]zirconocene (51).

For these complexes, the rate of carbonylation increases rapidly with increasing tr-alkyl character. Thus, (5-cis-butadiene)ZrCp2 (5a) is carbony-lated 2.5 times faster than the zirconocene complex of 1,2,5,6-tetramethyl-3,4-bis(methylene)tricyclo[3.1.0.0 ] hexane (51) (ambient temperature and 1 bar CO pressure) taken as a standard. Introduction of methyl groups at the internal carbon centers C2/C3 of the diene chain increases the carbonylation rate by a factor of 5 with phenyl groups at these positions increasing the rate by a factor of 250 (Table VIII). The organometallic reaction products have yet to be isolated or completely identified. Ultimately, zirconium enolate complexes (20) are probably formed in these... 

C12H9F603Rh Rhodium (4,4, 5-)/3-3,4-Bis-[methylen]-5-dehydro-pentanoyl)-(l, 1,1,5,5,5-hexafluor-2,4-pentadionato)-XIII/9b, 414... 

The rDA cycloieversitHi of a protected butadiene adduct has been applied to the synthesis of unsaturated oxygen heterocycles. The very unstable 2,3-dihydro-2,3-bis(methylene)furan and its 4-methyl derivative have been generated by rDA reaction of 4,5,6,7-tetrahydrobenzofuran and its dimethylated derivative (equation 82). Characterization of these dienes was accomplished by trapping with various dienophiles. This method was extended to a two-step rDA synthesis of tetramethylenetetrahydrofuran as shown in equatirai (83). ... 

Several 3-substituted 2-iminoaryl-4-(bis-trifluoromethyl)methylene-l, 3-thiazetid-ines are water repellant and are used for treating textiles.3-Substituted 2,4-bis-imino-l,3-thiazetidines may have pesticidal activity... 

A simple route to 2,3-bis(methylene)butanedioic esters involves carbonylation of l,4-bis(ethoxycarbonyloxy)-2-butyne. 2-Pyrimidyldiphenylphosphine is a suitable ligand for carbonylation of 1 -alkyne to give 2-substituted acrylic esters. ... 

The parent methylene-bridged resorcarene (II, R = H) was recently obtained by treatment of 2,4-bis(allyloxy)benzyl alcohol with Sc(OTf)3 in acetonitrile, followed by deallylation by ammonium formate and PdCl2(PPh3)2 . 

Double dehydrohalogenations have been used recently in the synthesis of a number of bis(methylene)triangulanes (Table 5). Typically, the starting dihalides are prepared by a sequence of cyclopropanation with chloromethylcarbene and monodehydrochlorination, in which a tetrahydropyranyl ether serves as the source of the bromide or iodide moiety (see Section 5.2.2.1.1.1.). The double elimination is carried out with potassium ier/-butoxide in dimethyl sulfoxide at or near room temperature, and gives low to moderate yields of bis(methyl-ene) products. In some cases mixtures of diastereomers were obtained due to the lack of stereospecificity of the preceding carbene addition to the double bond which consequently led to the presence of a mixture in the starting material. The procedure is illustrated by the synthesis of 1,4-bis(methylene)spiropentane (2). ... 

X = Cl, Br) were treated with potassium tert-butoxide in tetrahydrofuran to give 80% and 40% yield, respectively, of 7,7-dichloro- and 7,7-dibromo-2,3-bis(methylene)bicyclo-[4.1.0]heptane (19, X = Cl, Br). Elimination of the corresponding bis(mesylates) (see Section 5.2.2.3.) gave only low yields of bis(methylene) products. 

A number of dicycloproparenes have been prepared by way of the l-bromo-2-chlorocyclo-propene adducts in moderate to very good yields (Table 10). A special example of this procedure is the synthesis of li/,4/f-dicyclopropa[A,g]naphthalene (18) in 52% yield from the cycloadduct 17 of 1-bromo-2-chlorocyclopropene with 7,7-dichloro-3,4-bis(methylene)bi-cyclo[4.1.0]heptane (16), in which the elimination described in this section is combined with the double elimination of a 1,1-dichlorocyclopropane vide supra). 

A double mesylate elimination using potassium /ert-butoxide in tetrahydrofuran was attempted as a means of preparing 7,7-dichloro-2,3-bis(methylene)bicyclo[4.1.0]heptane (14, X = Cl) and its 7,7-dibromo analog from the corresponding diols. However, only low yields of the dienes... 

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