Vinylene carbonate synthesis

Enandoselecdve total synthesis of andhingal agent Sch-38516 is reported. Stereocontrolled carbohydrate synthesis is based on the 1,3-dipolar cycloaddidon of chiral nkrone to vinylene carbonate, as shovm in Eq. 8.53. ... 

Scheme 40 Synthesis of furanose-fused y-butyrolactones by photocycloaddition of vinylene carbonate to substituted butenolides...

The known adduct (385) of furan and vinylene carbonate, previously used for the synthesis of some cyclitols,256,257 has been transformed into DL-ribose derivatives. After hydroxylation of 385 and subsequent formation of the isopropylidene derivative, the carbonate group was removed by treatment with barium hydroxide, and the resulting diol was cleaved by oxidation with permanganate. Dicarboxyl-ic acid 386 gave, upon treatment with acetic anhydride, cyclic anhydride 387. The reaction of 387 with azidotrimethylsilane produced... 

Ethenediyl carbonate (l,3-dioxol-2-one vinylene carbonate, 417) is a readily available,270 versatile synthon having pronounced dienophilic properties.270-275 Diels-Alder adducts of 417 with 1,4-di-acetoxy-1,3-butadiene and furan were selectively converted into cy-clitols,256 257-275 and also served as precursors of DL-ribose derivatives258 (see Section IV, 2). Another possibility of applying 417 as an equivalent of a 1,2-dihydroxyethane unit has been demonstrated in a synthesis of racemic apiose. Photochemical cycloaddition of 417 to 1,3-diace-toxy-2-propanone (418) gave the oxetane derivative 419, which, on alkaline hydrolysis, afforded DL-apiose (420) in 23% yield.1... 

A synthesis of the well-known natural products, the inositols, begins with a Diels-Alder reaction between furan and vinylene carbonate (73JOC117). Both the exo and endo oxabicyclo[2.2.1]hept-5-ene-2,3-diol carbonate adducts were obtained. fraus-Hydroxyla-tion of the endo adduct via the epoxide (33) afforded D-l,4-anhydroinositol (34). Hydrolysis of this compound with acetic acid and a small amount of sulfuric acid yielded alio- (35) and myo-inositol (36 Scheme 7). 

The classical diene synthesis has been used for building the six-membered ring in the preparation of a/to-inositol by Criegee and Becher.36 trans, trans-Diacetoxybutadiene (XVI) and vinylene carbonate (XVII) condensed at 205-210° to an addition product (XVIII). Hydroxylation of this compound by osmium tetroxide, followed by hydrolysis, gave aWo-inositol the bulky osmium tetroxide approaches from the unhindered side of the molecule and the other possible product of the hydroxylation, m-inositol, is not formed.4 trans-Hydroxy 1 ation of XVIII would give epi-inositol. 

Several new variations of methods for preparation of indoles by Pd-mediated cyclization were reported. Vinylene carbonate was found to be a satisfactory C2-C3 precursor for synthesis of N-acylindolin-2-ols and A-acylindoles from o-iodoacetanilides under Heck conditions. <95H(41)1627>... 

The ability of furan to undergo both the forward and reverse Diels-Alder reaction has been used to synthesize 1,3-dioxoles, and the reaction appears to have wide applicability. In Scheme 42 the synthesis of 2-phenyl-l,3-dioxole is shown. The key to the process is the dialcohol (119), which is obtained from vinylene carbonate as shown. The dialcohol (119) has the potential of serving as an intermediate for a variety of 2-substituted 1,3-dioxolanes (73JA7161). 

When ethylene carbonate is monochlorinated, the chloroethylene carbonate thus obtained is the starting material for the synthesis of vinylene carbonate which is used in radical polymerization to yield high-molecular weight polymers and copolymers or in Diels-Alder cycloadditions [Scheme 174 ] (Ref. 227). 

Periodate cleavage of an oxabicyclic diol was also a key step in the synthesis of citreoviral from the Diels-Alder adduct of 2,4-dimethylfuran and vinylene carbonate [136]. 

Nitrogen-containing heterocyclic enone systems also reacted with allene to give (2 + 2)-cycloadducts, as was shown in alkaloid synthesis.178 As the keystep in the synthesis of an annotinine derivative, allene was added to 157 and the adduct 158 was obtained in quantitative yield. Various uracils have been modified by photochemical (2 + 2)-cycloaddition with olefins, e.g., vinylene carbonate,17,18° vinyl ethers, vinyl acetates, and (cetene acetals yielded 159.181 Very recently the photochemical addition of cyanoethylenes to 2-pyridones has been observed to yield mixtures of tetrahydroazocin-2-ones (160) and (2 + 2)-cycloadducts (161).182... 

Annulation of heterocycles with a cyclobutene ring has been achieved by photochemical (2 + 2)-cycloaddition with acetylenes. Both maleic anhydride and N-substituted maleimides yielded 3-oxa- or 3-aza-bicyclo[3.2.0l-hept-6-ene-2,4-diones (167).,89,9° Vinylene carbonates also entered into a cycloaddition reaction with acetylenes to afford 168, which has been employed as starting material for the synthesis of cyclo-butadiene(tricarbonyl)iron or cyclobutenedione.19,-193 3,4-Dihydro-2/f-pyran and 5-methyl-2,3-dihydrofuran reacted with diphenylacetylene to... 

Bulk polymerization of vinylene carbonate (VCA) initiated by 60Co y-rays was studied at 30°-110°C at a constant dose rate of 1 - 105 rad/hr. An overall activation energy of 5.0 kcal/mole and a maximum reaction rate of 1 10 3 mole/l-sec were obtained. As has been reported, purification of the monomer is a crucial point because inhibiting impurities are formed during the synthesis. From experiments with chlorine-substituted ethylene and vinylene carbonates, we tentatively conclude that, in addition to mono- and dichloroethylene carbonate, dichloro-vinylene carbonate is mainly responsible for the inhibition. The copolymerization behavior of VC A with some chlorine-substituted olefins was studied. Chlorotrifluoroethylene (CTFE) is an especially suitable comonomer the reactivity ratios found were rVCA = 0.42 and rCXFE = 0.48. 

Generally, 1,2-disubstituted ethylene derivatives have only a small tendency for radical homopolymerization. An exception is vinylene carbonate (VCA) which can be easily polymerized by chemical as well as radiation initiation. However, the reaction is strongly affected by traces of impurities formed during the synthesis. Inhibition experiments are discussed with regard to the nature of the inhibiting impurities. The copolymerization behavior of VCA with some halo-substituted olefins was studied with chlorotrifluoroethylene (CTFE), a statistical copolymer with a slight tendency for alternation was obtained. 

Field and Schaefgen (5) demonstrated that a high molecular weight poly (vinylene carbonate) (PVCA) was obtained if the first step of the synthesis, photochlorination of ethylene carbonate, was carried out in CC14 instead of bulk reaction and if the monomer was distilled from NaBH4 shortly before polymerization. On the other hand, bulk chlorination led invariably to poor quality VCA. 

We attribute the observed inhibition to dichlorovinylene carbonate. There are good arguments for this assumption the photochlorination of ethylene carbonate is not restricted to monosubstitution, but it leads to a whole spectrum of chlorinated products. Separation by rectification is difficult since the chlorine-substituted derivatives of ethylene and vinylene carbonate show a marked anomaly of boiling points (I). One byproduct of the chlorination reaction is trichloroethylene carbonate which, in spite of careful distillation, remains in traces with the monochloro compound and is dehydrohalogenated in the second step of the synthesis to give dichlorovinylene carbonate. 

Exploration of the template controlled free-radical oligomerization of other activated olefins began with standard monomers utilized in bulk polymer synthesis and the template 63. Vinyl acetate and acrylonitrile led only to uncontrolled polymerization, while vinylene carbonate did not react under the standard experimental conditions. More exotic monomers, such as vinyl trifluoroacetate and rert-butyl acrylate, were also unsuccessful. Only methyl acrylate polymerization was arrested by template 64 to provide the macrocyclized product 96 in modest yield as a mixture of five diastereomers (Scheme 8-25). Subsequent studies with the more effective thiophenyl-bearing template 63 at lower temperatures improved this yield to 35%. The diastereomer distribution was reminiscent of the methyl methacrylate-derived product, although no stereochemical assignments were made in this case either. 

The dienophilic properties of vinylene carbonate (1,3-dioxol-2-one, 6) have been repeatedly exploited for the synthesis of cyclic polyols. Recently a number of ribofuranose derivatives have been synthesized starting from 6. The known adduct 7, obtained from 6 and furan, was c/r-hydroxylated, and after acetonation was hydrolyzed with base and cleaved with permanganate to give the dicarboxylic acid 8. The corresponding anhydride 9 gave, on treatment with trimethylsilyl azide, the isocyanate 10, which in turn was converted into the carbonate 11 on addition of methanol. The monoester 12, obtained in the reaction of anhydride 9 with isopropanol, was effectively resolved into enantiomers by the use of brucine or (/ )-l-(2-naphthyl)ethylamine. ... 

A -methylpyrrolidine to a number of ketones. When these intermediates are generated in the presence of (57 )-5-menthyloxyfuran-2[5il/]-one addition takes place to the double bond of the furanone. The adducts obtained from the addition of vinylene carbonate to such homochiral furanones have been used in a new stereoselective synthesis of butyrolactones of lyxofuranose. ... 

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