Oxepins synthesis

Tribenzo[6,d/]thiepin synthesis, 7, 587 Tribenzoxepins resolution, 7, 14 Tribenz[6,4/ oxepins synthesis, 7, 581... 

Dibenz[6,/]oxepin, 10,11-dihydro-applications, 7, 590 Dibenz[c,e]oxepin, dihydro-conformational interchange, 7, 549 Dibenz[6,/]oxepinylpiperazine, 10,11-dihydro-properties, 7, 590 Dibenz[6,g]oxocin synthesis, 7, 669... 

Oxepin, 2-acetoxy-2,3,4,5-tetrahydro-thermal reactions, 7, 559 Oxepin, 3-chloro-synthesis, 3, 725 Oxepin, 2,3-dihydro-cycloaddition reactions, 7, 563 nucleophilic reactions, 7, 562 reduction, 7, 563 Oxepin, 2,5-dihydro-synthesis, 7, 578, 580 Oxepin, 4,5-dihydro-formation, 7, 579 reduction, 7, 563 synthesis, 7, 579 Oxepin, 2,7-dimethyl-NMR, 7, 552... 

Oxepin, 4-ethoxycarbonyl-2,3,6,7-tetrahydro-synthesis, 7, 578 Oxepin, 2-methyl-enthalpy of isomerization, 7, 555 Oxepin, 2,3,4,5-tetrahydro-reduction, 7, 563 synthesis, 7, 578 Oxepin, 2,3,4,7-tetrahydro-synthesis, 7, 578 Oxepin, 2,3,6,7-tetrahydro-oxidation, 7, 563 reduction, 7, 563 Oxepin-2,6-dicarboxylic acid stability, 7, 565 Oxepinium ions synthesis, 7, 559 Oxepins, 7, 547-592 antiaromaticity, 4, 535 applications, 7, 590-591 aromatization, 7, 566 bond lengths and angles, 7, 550, 551 cycloaddition reactions, 7, 27, 569 deoxygenation, 7, 570 dipole moment, 7, 553 disubstituted synthesis, 7, 584... 

H-Pyran, 2-alkoxy-4-methyl-2,3-dihydro-conformation, 3, 630 4H-Pyran, 2-amino-IR spectra, 3, 593 synthesis, 3, 758 4H-Pyran, 4-benzylidene-synthesis, 3, 762 4H-Pyran, 2,3-dihydro-halogenation, 3, 723 hydroboration, 3, 723 oxepines from, 3, 725 oxidation, 3, 724 reactions, with acids, 3, 723 with carbenes, 3, 725 4H-Pyran, 5,6-dihydro-synthesis, 2, 91 4H-Pyran, 2,6-diphenyl-hydrogenation, 3, 777 4H-Pyran, 6-ethyl-3-vinyl-2,3-dihydro-reactions, with acids, 3, 723 4H-Pyran, 2-methoxy-synthesis, 3, 762 4H-Pyran, 2,4,4,6-tetramethyl-IR spectra, 3, 593 4H-Pyran, 2,4,6-triphenyl-IR spectra, 3, 593... 

The same procedure was applied to the synthesis of pacharin (1,6-dihydroxy-8-methoxy-7-methyldibenz[if),/]oxepin), a constituent of the heartwood of Bauhinia racemosa Lamk.61... 

Under photochemical conditions, 12-oxatricyclo[7.2.1.02,8]dodeca-2(8),3,6,10-tetraen-5-one gives 8//-cyclohept[c/]oxepin-8-one in good yield.147 This reaction has been applied to the synthesis of a number of 2- and 2,4-substituted 8//-cyclohept[rf]oxepin-8-ones 17 147,148... 

Another application of this method is the synthesis of 5,10-epoxy[10]annulene (7) from 2,3.6,7-tetrabromo-4a,8a-epoxydecahydronaphthalene.152-154 The byproduct is 1-benzoxepin (8). The 5,10-cpoxyannulcnc (7) incorporates the oxepin structure. The annulene can be converted to 1-benzoxepin by proton catalysis.153154... 

Ring enlargement via an insertion of a carbene generated in the a-position to the ring is an established method and has also been applied to the synthesis of oxepins. The ()3-allylpalladium chloride catalyzed decomposition of substituted ethyl diazo(4/7-pyran-4-yl)acetates in benzene at room temperature gives ethyl oxepin-4-carboxylates 1 in excellent yield.190 The ester function can be replaced by the phosphonate group and other P = 0-functions (see Houben-Weyl,... 

Treatment of the 1,2-oxazines 52 with carbon monoxide at 1000 psi in the presence of cobalt carbonyl brings about insertion of carbon monoxide to form the 1,3-oxazepines S3 <96TL2713>. A convenient route to P-lactams fused to oxepines is made available by alkene metathesis. Thus reaction of 4-acetoxyazetidin-2-one with ally alcohol in the presence of zinc acetate, followed by iV-allylation of the nitrogen affords the derivative 54 which cyclises by RCM to form the oxazepinone 55 <96CC2231>. The same communication describes a similar synthesis of 1,3-dioxepines. 

Kurakawa, M., Sato, F., Masuda, Y., Yoshida, T., Ochi, Y., Zushi, K., Fujiwara, L, Naruto, S., Uno, H. and Mat-sumoto, J. (1991). Synthesis and biological activity of Il-(4-(cinnamyl)-l-piperazinyl)-6,l l-dihydrodibenz[6,e] oxepin derivatives, potential agents for the treatment of cerebrovascular diseases. Chem. Pharm. Bull. 39, 2564-2573. 

Oxepin is in equilibrium with benzene oxide by a [3,3]-sigmatropic shift. Advantage has been taken of this equilibrium to develop a short synthesis of barrelene. Outline a way that this could be done. 

Hydride and 1,2-alkyl shifts represent the most common rearrangement reactions of carbenes and carbenoids. They may be of minor importance compared to inter-molecular or other intramolecular processes, but may also become the preferred reaction modes. Some recent examples for the latter situation are collected in Table 23 (Entries 1-10, 15 1,2-hydride shifts Entries 11-15 1,2-alkyl shifts). Particularly noteworthy is the synthesis of thiepins and oxepins (Entry 11) utilizing such rearrangements, as well as the transformations a-diazo-p-hydroxyester - P-ketoester (Entries 6, 7) and a-diazo-p-hydroxyketone -> P-diketone (Entry 8) which all occur under very mild conditions and generally in high yield. 

For the synthesis ofthiepins and oxepins, [(ri3-C3Hs)PdCl]2-catalyzed decomposition of 4-diazomethyl-4-methyl-4/f-thiopyrans 387) or -pyrans38] ) is the method of choice. Purely thermal decomposition of the former diazo compounds would require higher temperatures and thus would cause extrusion of sulfur from the primarily formed thiepin, yielding a benzene derivative. 

An example illustrating the synthesis of condensed oxepins by the cobalt-catalyzed reaction of bistrimethylsilylacetylene with a hexa-l,5-diyne derivative is shown in Scheme 175.234 This type of process has been discussed earlier in the context of pyran synthesis (see Scheme 158 in Section V,B,2). 

The single crystal X-ray structure of the enantiopure tetrahydro oxepin-2-one 61, a mimic of steroidal androgens, has been reported <06ZN(B)111>. A new procedure has been described for the synthesis of substituted furano-fused oxepines based on expoxidation of strained fused cyclobutenes followed by thermal rearrangement <06OL5183>. 

Ueda et al. reported the synthesis of the novel diazepines (82 X = NMe) and oxepines (82 X = O) starting from the pyrimidin-3,5-dione 81 <00JHC1269>. 

The examples shown in Scheme 5 demonstrate the potential utility of these stereoselective alkylation technologies in synthesis. Thus, preparation of rac-14 through catalytic RCM of rac-13 (85% yield) and subsequent Zr-catalyzed resolution of the resulting racemic TBS-protected oxepin affords (S)-23 after silyl group deprotection. Diastereoselective alkylation with nBuMgBr affords (S)-24... 

The availability of oxepins that bear a side chain containing a Lewis basic oxygen atom (entry 2, Table 6.4) has further important implications in enantioselective synthesis. The derived alcohol, benzyl ether, or methoxyethoxymethyl (MEM) ethers, in which resident Lewis basic heteroatoms are less sterically hindered, readily undergo diastereoselective uncatalyzed alkylation reactions when treated with a variety of Grignard reagents [17]. The examples shown below (Scheme 6.7) demonstrate the excellent synthetic potential of these stereoselective alkylations. 

Van Boom and co-workers published an expeditious route to chiral oxepines with monosaccharide derivatives as precursors. The synthesis was accomplished by treatment of 210 with alkoxyallenes 8 under Rutjes s optimized reaction conditions (Scheme 8.50) [121]. 

A related dienediol-phenol rearrangement which can occur by different pathways was reported as a new method for synthesis of the oxepine system180. Protonation of the starting diol 344 produces a cation 345 which can follow normal dienone-phenol rearrangement (path a) when the substituents R2 = Me, Ph and R1 = t-Bu are eliminated in the step 346 — 347. However, when R1 = t-Bu and R2 is a substituted phenyl which decreases the nucleophility, the cationoid intermediate 345 cyclizes to the oxonium ion 348 (path b) which then undergoes deprotonation to give the oxepine 349 (equation 124)180. 

Among the valence-bond isomerisations leading to heterocyclic systems, the synthesis of derivatives of azepine (22) and oxepin (28) have been specially successful (Scheme 6.13) [32]. 

Kiyama, R., Honma, T., Hayashi, K., Ogawa, M., Hara, M., Fujimoto, M., and Fujishita, T. Angiotensin II receptor antagonists. Design, synthesis, and in vitro evaluation of dibenzo[a,d]cycloheptene and dibenzo[b,f oxepin derivatives. 

The synthesis of cyclic ethers 137 was achieved by a Fischer indole synthesis starting from cyclic keto arylhydrazones generated in situ from 4-(hydroxy-methylene)-3,4-dihydrobenzo[ 7]oxepin-5(2H)-one 136 and the corresponding diazonium salt (Equation (20), 1993JHC1481). 

The synthesis of these rings involves annulation of the furan ring onto the preformed benzoxepine core or intramolecular oxepine C-C bond formation of the furan precursors. Thus, 2-methyldibenzo[ 7,/]furo[2,3-d]oxepines 148 (R = H, Cl)... 

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