Norbornene, amination

A dry 250-ml flask was charged with 80 ml of THF, pyridine (9.7 g), and norbornene amine (12.3 g) and then cooled to 0°C, treated with trifluoromethanesulfonylchloride (16.9 g) and stirred 4 hours. The mixture was filtered and the THF evaporated. The residue was dissolved in diethyl ether and washed with 3.5% hydrochloric acid, followed by water until a pH of 7 was obtained. Diethyl ether mixture was dried using Na2S04 and concentrated, and an oily material was isolated. 

Kiji and co-workers [87] investigated the composition and microstructure of alternating olefin-carbon monoxide copolymers and their derivatives including ethylene-styrene-carbon monoxide alternating polymer, norbornene-amine copolymer and polymers modified with phosphorus pentasulfide or phosphorus pentoxide or primary amines. 

Allyl methylcarbonate reacts with norbornene following a ruthenium-catalyzed carbonylative cyclization under carbon monoxide pressure to give cyclopentenone derivatives 12 (Scheme 4).32 Catalyst loading, amine and CO pressure have been optimized to give the cyclopentenone compound in 80% yield and a total control of the stereoselectivity (exo 100%). Aromatic or bidentate amines inhibit the reaction certainly by a too strong interaction with ruthenium. A plausible mechanism is proposed. Stereoselective CM-carboruthenation of norbornene with allyl-ruthenium complex 13 followed by carbon monoxide insertion generates an acylruthenium intermediate 15. Intramolecular carboruthenation and /3-hydride elimination of 16 afford the -olefin 17. Isomerization of the double bond under experimental conditions allows formation of the cyclopentenone derivative 12. 

A variety of catalytically active five-coordinate tungsten oxo and imido alkylidene complexes also have been prepared that contain some donor amine or pyridine linked either to the imido ligand or to a phenyl ligand bound to the metal (A, Scheme 2) [101-105]. Such species show metathesis activity (e.g., ROMP of norbornene),but there does not appear to be any proof that the integrity of the initiator is maintained. 

The living character of the ring opening metathesis polymerization described earlier in this review enables a simple preparation of functionalized norbornene-based monoliths. Adding one more in situ derivatization step that involves functional norborn-2-ene and 7-oxanorborn-2-ene monomers that react with the surface-bound initiator, the pores were provided with a number of typical functional groups such as carboxylic acid, tertiary amine, and cyclodextrin [58,59]. 

However, the chemical shift for a o-bound M-aryl bond appears at high frequency, often between 130 and 180 ppm. Both the cydometallated nitroso-amine compound 65 [63-65] and the Pd(ii)(Duphos) complex 66 (an intermediate in the enantioselective hydroarylation of norbornene) [66] represent typical examples. 

In some thermolysis reactions, amines (90 and 91) have been characterized.108,111,112,457 When R1 = CH2OH and R2 = H in Scheme 164, the aziridine undergoes spontaneous rearrangement (Scheme 166).125 An endo-triazoline adduct from norbornene yields a polymer as the principal... 

The isomerization of 5-vinyl-2-norbornene to 5-ethylidene-2-norbornene has been performed using a catalytic system consisting of an alkali metal hydride and an amine. The activity of the alkali metal hydride increased with increasing size of the alkali metal KH > NaH > LiH. Among the various amines tested, only aliphatic 1,2-diamines exhibited the activity for the isomerization. Electron paramagnetic resonance (EPR) and UV-visible spectroscopic experiments on the active species suggest that the isomerization of 5-vinyl-2-norbornene proceeds through a radical mechanism.167... 

Among the carbonylative cycloaddition reactions, the Pauson-Khand (P-K) reaction, in which an alkyne, an alkene, and carbon monoxide are condensed in a formal [2+2+1] cycloaddition to form cyclopentenones, has attracted considerable attention [3]. Significant progress in this reaction has been made in this decade. In the past, a stoichiometric amount of Co2(CO)8 was used as the source of CO. Various additive promoters, such as amines, amine N-oxides, phosphanes, ethers, and sulfides, have been developed thus far for a stoichiometric P-K reaction to proceed under milder reaction conditions. Other transition-metal carbonyl complexes, such as Fe(CO)4(acetone), W(CO)5(tetrahydrofuran), W(CO)5F, Cp2Mo2(CO)4, where Cp is cyclopentadienyl, and Mo(CO)6, are also used as the source of CO in place of Co2(CO)8. There has been significant interest in developing catalytic variants of the P-K reaction. Rautenstrauch et al. [4] reported the first catalytic P-K reaction in which alkenes are limited to reactive alkenes, such as ethylene and norbornene. Since 1994 when Jeong et al. [5] reported the first catalytic intramolecular P-K reaction, most attention has been focused on the modification of the cobalt catalytic system [3]. Recently, other transition-metal complexes, such as Ti [6], Rh [7], and Ir complexes [8], have been found to be active for intramolecular P-K reactions. 

This precedents prompted several groups to develop reaction protocols that lead exclusively to the reduced products (the reductive PKR), in order to use them in synthesis. Thus, Becker obtained diazabicyclooctanones like 208 from amines (207) as the only reaction product when they used DSAC conditions under an inert atmosphere. The nitrogen atmosphere was essential as in air they obtained mixtures of the cyclopentanones and the cyclopentenones. This group has used this methodology for the synthesis of azaadamantanes like 209 as part of the structure of certain antagonists (Scheme 59) [ 182-184], Addition of TFA to the reaction favors the formation of reduced products. A series of alkynes produced cyclopentanones as the major product when reacted with norbornene, Co2(CO)8 and TFA. The authors think TFA reacts with the cobalt complex 210, prior to the reductive elimination that gives the final product 211 (Scheme 60) [185]. 

A different catalytic cycle for alkene hydroamination is initiated by the oxidative addition of the N-H bond to the metal, followed by insertion of the alkene into the metal-nitrogen bond and reductive elimination to form the amine. The oxidative addition of unactivated N-H bonds to platinum(O) complexes is thermodynamically unfavorable, so the catalytic cycle cannot be completed17, but the successful iridium(I)-catalyzed amination of norbornene with aniline has been reported18. 

The diastereoselective addition of aniline to norbornene was accomplished using a catalytic amount of iridium(I). As the intermediate azametallacyclobutane 2 could be isolated its stereochemistry was determined by X-ray analysis both iridium and nitrogen occupy the exo position41. However, the scope of the amination method, with respect to the nature of the amine and the structure of the alkene, was not determined. Conversely, the analogous rhodium(I)-cat-alyzed reactions of norbornene and aromatic amines gave mixtures of hydroamination and hydroarylation products106. 

A soln of iV-hydroxy-5-norbornene-2,3-dicarboximide (17.9 g, 100 mmol) and A,iV-dimethylaniline (12 g, 95 mmol) in THF/benzene (1 3, 100 mL) was added dropwise to a soln of COCI2 (9.9 g, 100 mmol) in benzene (50 mL) at 0-5 °C. The amine hydrochloride was filtered off, and the soln was concentrated. The residue was dissolved in CH2CI2 (50 mL), and a trace of bis(5-norbornene-2,3-dicarboximido) carbonate was removed by filtration. The solvent was removed and the residue triturated with Et20 (50mL) to give 5-norbomene-23-dicarboximido chloroformate 5deld 20.5 g (85%) mp 98-100 °C. 

Recently, Schmitz has reported aminations of weak nucleophiles such as alkenes to produce aziridines directly. Although simple aliphatic olefins do not react, styrene, indene, acrylonitrile, and norbornene were converted to aziridines. The reaction of 3-ethyl-3-methyloxaziridine with diphenylcyclopropenone may be a reaction of this type. ... 

ButG5H3, G9H6) have been synthesized either by the standard salt metathesis or the amine elimination procedure. These compounds are used as pre-catalysts for norbornene homopolymerization and ethylene-norbornene co-poly-merization. The influence of the catalyst symmetry and structure on the activity, norbornene incorporation, and polymer and co-polymer microstructure has been studied.706... 

When norbornadiene is allowed to react under the influence of a nickel catalyst in amine, 5-tolyl-2-norbornene 93 is formed [113]. After dimerization of norbornadiene, (3-carbon elimination occurs to open the norbornane ring of 92. An analogous cleavage of a norbornane ring was observed in the palladium-catalyzed reaction of bromobenzene with norbornene [114]. 

Earher mechanistic studies by Milstein on a achiral Ir catalyst system indicated that the iridium catalyzed norbornene hydroamination involves amine activation as a key step in the catalytic cycle [27] rather than alkene activation, which is observed for most other late transition metal catalyzed hydroamination reactions [28]. Thus, the iridium catalyzed hydroamination of norbornene with aniline is initiated by an oxidative addition of aniline to the metal center, followed by insertion of the strained olefin into the iridium amido bond (Scheme 11.4). Subsequent reductive elimina tion completes the catalytic cycle and gives the hydroamination product 11. Unfor tunately, this catalyst system seems to be limited to highly strained olefins. 

Ketones are also produced from amines by oxidation with KMn04 supported on copper(II) sulfate pentahydrate in dichloromethane. Bridged alkenes such as norbornene are cleaved with the same reagent. This method is an alternative to ozonolysis. ... 

Al-Badri and co-workers [55] studied the effect of fine-tuning the cationic parameter of synthetic mimics of antimicrobial peptides (SMAMP) on haemolytic and antibacterial activities. A category of novel norbornene monomers that carry one, two or three Boc-protected amine-functionalities was synthesised (Figure 3.8). ROMP of the monomers, followed by deprotection of the amine groups led to cationic antimicrobial polynorbornenes that carry one, two and three charges per monomer repeat unit. It was observed that enhancing the number of amine groups on the most hydrophobic polymer effectively decreased its haemolytic activity. 

The use of both LIU and HIU has been shown to increase the efficiency of the P-K reaction, which involves the formation of cyclopentenone from the annulation of a cobalt alkynyl carbonyl complex and an alkene. The use of low-power ultrasound, as for example, from a cleaning bath, although capable of producing intramolecular P-K reactions, generated relatively low cyclization yields. The motivation for the use of high intensity came from its ability, as previously described, to effectively decarbonylate metal carbonyl and substituted metal carbonyl complexes. Indeed, HIU produced by a classic horn-type sonicator has been shown to be capable of facile annulation of norbornene and norbornadiene in under 10 min in the presence of a trimethylamine or trimethylamine N-oxidc dihydrate (TMANO) promoter, with the latter promoter producing cleaner product mixtures. This methodology also proved effective in the enhancement of the P-K reaction with less strained alkenes such as 2,5-dihydrofuran and cyclopentene, as well as the less reactive alkenes -fluorostyrene and cycloheptene. The mechanism has been postulated to involve decarbo-nylation of the cobalt carbonyl alkyne, followed by coordination by the amine to the vacant coordination sites on the cobalt. 

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