Norbomene hydrogenation

Keywords large scale, gas-solid reaction, catalytic hydrogenation, norbomene dicarboxylic anhydride, stereospecific... 

The preference for endo attack in 7,7-dimethylnorbomene is certainly steric in origin, with the 7-methyl substituent shielding the exo direction of approach. The origin of the preferred exo-attack in norbomene is more subject to discussion. A purely steric explanation views the endo hydrogens at C—5 and C—6 as sterically shieldihg the endo approach. There probably is also a major torsional effect Comparison of the exo and endo modes of reproach shows that greater torsional strain develops in the endo mode of... 

A somewhat more complex application of this notion is represented by the CNS stimulant fencamfine (83). Diels-Alder addition of cyclopentadiene and nitrostyrene affords the norbomene derivative, 80. Catalytic hydrogenation reduces both the remaining double bond and the nitro group (81). ° Condensation with acetaldehyde gives the corresponding imine (82) a second reduction step completes the synthesis of fencamfine (83). ... 

In contrast with exo (top) facial selectivity in the additions to norbomene 80 [41], Diels-Alder reaction between isodicyclopentadiene 79 takes place from the bottom [40] (see Scheme 32). To solve this problem, Honk and Brown calculated the transition state of the parent Diels-Alder reaction of butadiene with ethylene [47], They pointed ont that of particular note for isodicyclopentadiene selectivity issue is the 14.9° out-of-plane bending of the hydrogens at C2 and C3 of butadiene. The bending is derived from Cl and C4 pyramidalization and rotation inwardly to achieve overlap of p-orbitals on these carbons with the ethylene termini. To keep the tr-bonding between C1-C2 and C3-C4, the p-orbitals at C2 and C3 rotate inwardly on the side of the diene nearest to ethylene. This is necessarily accompanied by C2 and C3 hydrogen movanent toward the attacking dienophile. They proposed that when norbomene is fused at C2 and C3, the tendency of endo bending of the norbomene framework will be manifested in the preference for bottom attack in Diels-Alder reactions (Schane 38). 

Falck has recently reported dehydrogenative silylation of heteroarenes with triethylsilane (18) [97]. Coupling with the Si-H bond of triethylsilane, rather than the disilane Si-Si bond, in conjunction with the use of norbomene that presumably acts as a hydrogen acceptor, gives good yields with indoles, thiophenes, and furans, under relatively mild condition (80°C). Unlike the reaction shown in Scheme 7, silylation of indole did not require protection of the N-H group. 

Ru(ti -C6H,)(CH3CN),](BF4)2 1-octene, 1-decene, styrene, 1-dodecene, cyclohexene, norbomene.dimethy 1 mateate, cyclohex-1 -ene-2-one, benzylideneacetone H20/benzene 90-110 C, 40 bar Hi Slow hydrogenation of ketones and aldehydes, too. [71]... 

The iridium(l) PCP pincer complexes 1 exhibit remarkable activity in the catalytic dehydrogenation of unfunctionalized alkanes (Scheme 12.1). The H2, which is formally produced during this process, may be transferred to either tert-butyleth-ylene (TBE) or norbomene (NBE) as a sacrificial hydrogen acceptor. For example, complex la converts cyclooctane (COA) to cyclooctene (COE) in the presence of TBE, which in turn is reduced to tert-butylethane (TBA ueo-hexane) [6]. 

Not shown in Table I are several adducts obtained by cycloaddition of the acridizinium ion with 5,6-endo-substituted norbomene derivatives. These adducts each have two (imequally shielded) methylene hydrogen atoms which make simple the NMR analysis of mixtures of syn (8) and anti (9). When the 5,6-endo chain (R) was of the type... 

Nair KP, Week M. Noncovalently functionalized poly(norbomene)s possessing both hydrogen bonding and coulombic interactions. Macromolecules 2007 40 211-219. 

Aryl azides react with olefins to give 1,2,3-A2-triazolines.201-203 Whereas unactivated olefins are sluggish toward aryl azides, strained bicyclic systems, on the contrary, are particularly reactive.204-208 The rate of phenyl azide addition to a series of olefins parallels the heat of hydrogenation (Table Vffl).107 This thermodynamic parameter is a measure for the degree of strain associated with these molecules.200 Bicyclo[2.2.1]hep-tenes, such as norbomene (37), react readily at room temperature, and the addition occurs at the less hindered exo side (39).,06 1°7 210 211 A striking example of the increased... 

With DIOP-Pd(0) or -Ni(0) complexes as catalysts, moderate optical yields of up to 35% have been observed (126). Norbomene is convertible to the exo nitrile with up to 40% ee when a BINAP-Pd(0) complex is used (Scheme 57) (127). Ni(0) complexes of sugar-derived 1,2-diol phosphinites catalyze highly selective asymmetric addition of hydrogen cyanide to vinylarenes (128). This method gives the 2-naphthalene-2-propionitrile precursors of nonsteroid anti-inflammatory agents in up to 85% ee and in high yield. 

Hydrocyanation is also catalyzed by [Pd(PPh3)4] (103) and [Pd P(OPh), 4] (132), again in both cases in the presence of excess ligand.604 Complex (132) is an effective catalyst for the addition of hydrogen cyanide to cyclic monoenes and dienes such as norbomene and norbornadiene 605-606 ethylene also reacted readily. The product obtained from norbornene was the exo isomer (equation 165). When norbornadiene was the substrate, some of the endo product was formed.605... 

Hydroformylation of norbomene proceeds slowly in spite of the expected reactivity of the strained double bond. Racemization of the product aldehyde does not occur under the reaction conditions. The hydroformylation of methyl methacrylate gives only one isomer, which is a useful chiral synthon. Dimethyl itaconate also can be hydroformylated using (12) as the chiral ligand to give aldehyde product in 82% ee accompanied by hydrogenated ester.64... 

Hydrogenation of polymers of substituted norbomenes is frequently a valuable aid to the determination of structural detail and is best carried out using diimide (NH=NH) generated in situ by the decomposition of p-toluenesulphonohydrazide in xylene at 120 °C. This procedure works well and selectively even in the presence of groups such as COOMe and PPh2497. 

By using Josiphos ligands, palladium-catalysed hydrophosphorylation of norbomen-es with hydrogen phosphonates proceeds efficiently to give the corresponding phos-phonates in high enantioselectivities.90... 

Winstein, S. Shatavsky, M. Neighboring carbon and hydrogen. XXI. Anti-7 derivatives of norbomene as homoallylic systems. /. Am. Chem. Soc. 1956, 78, 592-597. 

Acetophenone Hydrogen chloride Magnesium 5-Chloro-2-norbomene Piperidine hydrochloride Formaldehyde ... 

Partially hydrogenated polymers derived from norbomene derivatives, [1], prepared by Miyaki [2] were low in birefringence, high in wavelength dependency birefringence, and excellent in transparency and heat resistance. Additional functionalized norbomene derivatives were prepared by Liaw [3],... 

Anhydrous Fe Cl3 catalyzes the stereospecific epoxidation of norbomene, the demethylation of A, A-dimethylaniline, and the oxidative cleavage of PhCMe(OH)CMe(OH)Ph (and other a-diols) by hydrogen peroxide (Table 11 and Scheme 4). For each class of substrate, the products parallel those that result from their enzymatic oxidation by cytochrome P-450. The close congruence of the prodncts indicates that the reactive oxygen in the Fe Cl3/HOOH model system and in the active form of cytochrome P-450 is essentially the same, with strong electrophilic oxene character (stabilized singlet atomic oxygen). 

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