2,5 norbomadiene

The intermolecular insertion of alkenes into rr-allylpalladium is unknown, except with norbomadiene(476]. On the other hand, the intramolecular insertion of alkene group in 766 into 7r-allylpalladium proceeds smoothly to give the... 

Cyclization. Constmction of ben2otrifluorides from aHphatic feedstocks represents a new technique with economic potential. For example, l,l,l-trichloro-2,2,2-trifluoroethane [354-58-5] and dimethyl itaconate [617-52-7] form 4-methoxy-6-trifluoromethyl-2JT-pyran-2-one [101640-70-4] which is converted to methyl 3-(trifluoromethyi)ben2oate [2557-13-3] ixh. acetjdene or norbomadiene (125). 

The reaction is about 50% faster in ethoxyethanol than in decane. Calculate the activation parameters at 150°C. Although precisely comparable data are not available, for the gas-phase isomerization of norbomadiene is 50kcal/mol. Draw a sketch... 

The oxidation of norhomadiene by i-butyl perbenzoate and Cu(I) leads to 1-t-butoxynorbomadiene. Similarly, oxidation with dibenzoyl peroxide and CuBr leads to 7-benzyloxynorbomadiene. In both cases, when a 2-monodeuterated sample of norbomadiene is used, the deuterium is found distributed at all seven carbons in the product. Provide a mechanism which could account for this result. In what w s does this mechanism differ from the general mechanism discussed on pp. 724-725 ... 

Early work established that S4N4 forms di-adducts with alkenes such as norbornene or norbomadiene. Subsequently, structural and spectroscopic studies established that cycloaddition occurs in a 1,3-S,S"-fashion. The regiochemistry of addition can be rationalized in frontier orbital terms the interaction of the alkene HOMO with the low-lying LUMO of S4N4 exerts kinetic control. Consistently, only electron-rich alkenes add to S4N4. 

Chemistry of conjugated heterocycles built from furan pyrrole, or thiophene ring fused with bicyclic (norbomadiene, bomene, or azanorbomene) skeletons 98YGK192. 

Abbreviations aapy, 2-acetamidopyridine Aik, alkyl AN, acetoniuile Ar, aryl Bu, butyl cod, 1,5-cyclooctadiene COE, cyclooctene COT, cyclooctatetraene Cp, cyclopentadienyl Cp , penta-methylcyclopentadienyl Cy, cyclohexyl DME, 1,2-dimethoxyethane DME, dimethylformamide DMSO, dimethyl sulfoxide dmpe, dimethylphosphinoethane dppe, diphenylphosphinoethane dppm, diphenylphosphinomethane dppp, diphenylphosphinopropane Et, ethyl Ec, feirocenyl ind, inda-zolyl Me, methyl Mes, mesitylene nb, norbomene orbicyclo[2.2.1]heptene nbd, 2,5-norbomadiene OTf, uiflate Ph, phenyl PPN, bis(triphenylphosphoranylidene)ammonium Pi , propyl py, pyridine pz, pyrazolate pz, substituted pyi azolate pz , 3,5-dimethylpyrazolate quin, quinolin-8-olate solv, solvent tfb, teti afluorobenzobaiTelene THE, tetrahydrofuran THT, tetrahydrothiophene tmeda, teti amethylethylenediamine Tol, tolyl Tp, HB(C3H3N2)3 Tp , HB(3,5-Me2C3HN2)3 Tp, substituted hydrotiis(pyrazol-l-yl)borate Ts, tosyl tz, 1,2,4-triazolate Vin, vinyl. 

Nitric oxide, 80 Nitrogen, 79 correlation with CO, 39 Nitromethane, 219 Nitrosome thane, 149 Nonbondmg orbitals, 5, 9, 28 Norbomadiene, 282... 

Table 1.5 Ni(COD)2/PPh3 catalyzed /zo/wo-Diels-Alder reactions of 2-carboxyethyl-norbomadiene with electron-deficient dienophiles...

When irradiated in stronger acid (FHSO3) at —60°, the tropylium ion is seen to isomerize cleanly to the norbomadien-7-yl cation (7) (Childs and Taguchi, 1970 Hogeveen and Gaasbeek, 1970). The ion 7 has been shown to be photochemically stable (Cabell and Hogeveen, 1972). However, it is known to revert to the tropylium ion thermally at temperatures above 45° (Lustgarten et al., 1967). 

In 15-58, we used the principle of conservation of orbital symmetry to explain why certain reactions take place readily and others do not. The orbital symmetry principle can also explain why certain molecules are stable though highly strained. For example, quadricyclane and hexamethylprismane are thermodynamically much less stable (because much more strained) than their corresponding isomeric dienes, norbomadiene and hexamethylbicyclo[2.2.0]hexadiene (108). Yet the... 

Norbomadiene A-Bromosuccinimide A-Chlorosuccinimide A-Iodosuccinimide Raney nickel... 

As discussed in connection with the facial selectivities of 7-methylidenenorbom-ane 46 and bicyclo[2.2.2]octene 48, the components of the molecules, i.e., n functionality and two interacting o orbitals at the two P positions, are the same, but the connectivity of these fragments, i.e., the topology of the n systems, is different (A and B, Fig. 9). A similar situation was found in the case of spiro[cyclopentane-l,9 -fluorene] 68 [96, 97] and 11-isopropylidenedibenzo-norbomadienes 71 (see 3.4.1 and 3.4.2) [123]. In these systems, the n faces of the olefins are subject to unsymmetrization due to the difference of the interacting orbitals at the P positions. In principle, consistent facial selectivities were observed in these systems. 

Recently, a Pd/Cu-catalyzed three-component coupling reaction of aryl halides, norbomadiene, and alkynols was reported to generate 2,3-disubstituted norbomenes in high yields in the presence of aqueous NaOH and a phase-transfer catalyst in toluene at 100°C (Eq. 3.39).151... 

Dehydrobenzene or benzyne 158 can be trapped by all manner of species. 1,2-Dehydro-o-carborane 159 has been shown to undergo many of the same reactions as its two-dimensional relative, 1,2-dehydrobenzene. Although dehydroaromatic molecules can be formed in a variety of ways, synthetic pathways to 1,2-dehydro-o-carborane are quite limited. An effective procedure reported so far78 first forms the dianion by deprotonation of o-carborane with 2 equiv. of butyllithium. Precipitated dilithium carborane is then treated with 1 equiv. of bromine at 0°C to form the soluble bromo anion 160. Thermolysis of 160 with anthracene, furan, and thiophene as substrates leads to the adducts 161-164.79 80 1,2-Dehydro-o-carborane reacts with norbomadiene to give both homo 2+4 and 2+2 addition, leading to three products 165-167, in a 7 1 ratio79. An acyclic diene, 2,3-dimethyl-... 

Tetranitromethane adds across various non-conjugated dienes to give cyclic products. The products with norbomadiene and cycloocta-1,5-diene are subject to spontaneous violent decomposition. 

Tung CH, Zhang LP, Li Y et al (1997) Intramolecular long-distance electron transfer and triplet energy transfer. Photophysical and photochemical studies on a norbomadiene-steroid-benzidine system. J Am Chem Soc 119 5348-5354... 

Experimentally, this reaction sequence was observed with hydrogen 70) or a substituted octenyl group721 in position 7 of the norbomadiene. In the calculations a methyl group was used as marker, to show the course of the rearrangement. 

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