2-bromoadamantane

The apocamphyl structure is particularly rigid, and bridgehead caibocationa become accessible in more flexible structures. The relative solvolysis rates of the bridgehead bromides 1-bromoadamantane, l-bromobicyclo[2.2.2]octane, and l-bromobicyclo[2.2,l]-... 

A 500-ml flask is equipped with a condenser and a magnetic stirrer and charged with 175 ml of water, 18 ml ofTHF, lOg of potassium carbonate, 6.5 g of silver nitrate, and 10 g of 1-bromoadamantane. The mixture is heated in a boiling water bath for 1 hour with stirring, cooled, and the crystallized 1-adamantanol is collected by filtration. It may be purified by dissolving it in THF and diluting the solution with water. The product has mp 289-290°. 

An alternate procedure has recently been described (5). In a 100-ml flask equipped with a condenser and a magnetic stirrer, 10 g of 1-bromoadamantane is mixed with 15 ml of 0.67 N hydrochloric acid and 13 ml of DMF. The mixture is heated at 105° for... 

The low reactivity of alkyl and/or phenyl substituted organosilanes in reduction processes can be ameliorated in the presence of a catalytic amount of alkanethiols. The reaction mechanism is reported in Scheme 5 and shows that alkyl radicals abstract hydrogen from thiols and the resulting thiyl radical abstracts hydrogen from the silane. This procedure, which was coined polarity-reversal catalysis, has been applied to dehalogenation, deoxygenation, and desulfurization reactions.For example, 1-bromoadamantane is quantitatively reduced with 2 equiv of triethylsilane in the presence of a catalytic amount of ferf-dodecanethiol. 

Vinyl cations also have been invoked as intermediates in the addition of carbonium ions generated in strong acid to acetylene (50-53). Sasaki et al (50) observed 1-adamantyl methyl ketone, 25, as the sole product in the reaction of acetylene with 1-bromoadamantane in concentrated H2SO4 at 5°. Bott (51), on the other hand, reported a mixture consisting of 75% 1-adamantylacetaldehyde,... 

Adamantanol has been prepared by oxidation of adamantane with peroxyacetic acetic" and by hydrolysis of 1-bromoadamantane with silver nitrate s or hydrochloric acid. ... 

Adamantanol is available from the following three suppliers Aldrich Chemical Company, Inc., Fluka AG, Buchs, Switzerland E. Merck, Darmstadt, Germany. It may also be prepared from adamantane by bromination to 1-bromoadamantane and hydrolysis. Adamantane is sold by the same three suppliers. 

Bromoadamantane and 1-bromoadamantane are reduced to adamantane in yields of 84% and 79%, respectively, when treated with triethylsilane and catalytic amounts of aluminum chloride.186 Similar treatment of benzhydryl chloride and exo-2-bromonorbomane gives the related hydrocarbons in yields of 100% and 96%, respectively.186 In contrast, 2-bromo-l-phenylpropane gives only a 43% yield of 1-phenylpropane the remainder consists of Friedel-Crafts alkylation products.186 Some alkyl halides resist reduction by this method, even when forcing conditions are employed. These include p-nitrobenzyl bromide, 3-bromopropanenitrile, and 5-bromopentanenitrile.186... 

Pyrrole fails to undergo a Heck reaction with 1-bromoadamantane [90], However, dihydropyrroles such as 131 and 132 undergo Heck reactions with ease, although the yields are variable [91-93]. Some examples are illustrated below. Since dihydropyrroles can be oxidized to pyrroles with a variety of reagents [94, 95], these Heck reactions of dihydropyrroles should constitute viable routes to pyrroles. 

Good stirring is important for the preparation of highly reactive calcium. A Schlenk tube is better than a flask for the reactor. Excess calcium salt was present during the oxidative addition reaction with 1 -bromoadamantane. 

Amantadine Amantadine, 1-adamantylamine (36.1.3), is synthesized from adamantane, which is first brominated with molecular bromine to make 1-bromoadamantane (36.1.1). Interacting this with acetonitrile in a Ritter reaction conditions gives 1-acetylaminoadaman-tane (36.1.2). Hydrolysis of the last with sodium hydroxide gives amantadine [1-6]. 

The triphase hydrolysis of 1-bromoadamantane with catalysts 50 (n = 1-16) and 51 was studied kinetically 170). The enthalpies of activation (AH ) for the catalyzed reactions were 6-12 kcal/mol lower than for the uncatalyzed reaction. (The free energies of activation were 1-2 kcal/mol lower). This considerable variation in AH was attributed to a much different microenvironment in catalysts 50 and 51 from that in the absence of the catalyst. Thus Regen 170> pictures both the organic phase and the aqueous phase in the polymer matrix, as if homogeneous. Studies using spin-labeled compounds also indicated that catalyst 50 affects the polarity and the motional freedom of the microenvironment171). 

In a 250-mL, round-bottomed flask equipped with magnetic stir bar, 1-bromoadamantane (35.0 g, 0.16 moles) is dissolved in 3,5-dimethylanilinef (92.0 g, 0.75 moles), yielding a clear, pale yellow solution. This is heated under nitrogen for 24-36 h at 140°C to form a thick brown liquid. The reaction is conveniently monitored by GC/MS. The brown liquid is extracted with ether (200 mL), washed with NaOH (100 mL of a 1 M solution), and vacuum distilled to remove excess aniline, leaving a dark brown solid. The solid is extracted into a minimum volume of hot methanol (ca. 160 mL) and cooled until crystallization occurs. The solid is collected on a sintered-glass frit and washed with cold methanol (2 x 20 mL) to afford white crystals. The filtrate is concentrated again to afford second and third crops. Yield 29.0 g (71%). 

Treatment of pyrazole with 1-bromoadamantane affords either 4-(l-adamantyl)pyrazole (94TL183, 94H(37)1623) or 3(5)-(l-adamantyl)pyrazole (94CL2079) depending on the conditions (heating in a sealed tube or heating in a microwave oven). (Other cases of C-alkylation of azoles are in Section 3.4.1.3.10). 

Tin hydrides bearing highly fluorinated substituents (fluorous chemistry) were used in the radical-mediated reduction of 1-bromoadamantane. The reaction was complete within 3 min under 35 W microwave irradiation (Scheme 4.42)68. 

In the adamantyl framework the /-silicon effect was studied by Grob and coworkers96,97. The first-y-trimethylsilyl substituent (cf 245) enhances the solvolysis rate of 1-bromoadamantane 246 by a factor of only 8.6 and the second trimethylsilyl group in... 

Laali et al.234 have developed a method to the highly selective pura-adamantylation of arenes (toluene, ethylbenzene, anisole) with haloadamantanes (1-chloro- and 1-bromoadamantane, l-bromo-3,5,7-trimethyladamantane) and 1-adamantanol promoted by triflic acid in butylmethylimidazolium triflate [BMIM][OTf] ionic liquid. In contrast to reactions mn in 1,2-dichloroethane, little or no adamantane byproduct was detected in [BMIM][OTf. Furthermore, no isomerization of para-tolyladamantane was observed supporting the intramolecular nature of the formation of meta isomers. In competitive experiments with benzene-toluene mixture (1 1 molar ratio), high substrate selectivities were found (kT/kB = 16-17) irrespective of the alkylating agent. This is in sharp contrast to values about unity measured in 1,2-dichloroethane. 

In a similar study, Nafion-H beads, 10% Nafion-H on silica, and 13% Nafion-silica were compared in the adamantylation of toluene with 1-bromoadamantane.239 13% Nafion-silica nanocomposite exhibited the highest activity and showed achangeinthe isomeric ratio of the two alkylated products the para/me ta ratio shifted to lower values in prolonged reaction (Table 5.20). Acidity is known to exert a significant influence on... 

Reaction conditions 5 ml of toluene, 1 mmol of 1-bromoadamantane, 0.2 g of catalyst, 111°C. Initial reaction rate, mmol (gcat min)-1. 

Data for solvolyses of 1 -bromoadamantane (54, X = Br in Scheme 2.19) in ethanol-water in Table 2.3 show that S is approximately independent of solvent composition, but the selectivity is inverse. Why is S < 1 for competing nucleophilic substitutions when ethanol is normally more nucleophilic than water A credible explanation is that the products are formed by front-side collapse of a solvent-separated ion pair (52 in Scheme 2.18) - the caged structure prevents rear-side approach, so attack must occur from the front-side, and the proportion of water in solvent-separated ion pairs must be greater than in the bulk solvent. 

Table 2.3 Product selectivities (Equation 2.11) for solvolyses of 1-bromoadamantane (54, X = ethanol-water at 75°C and 100°C [41 ]. Br) in...

Previously, it has been noted that the solvolysis rates of both 3-methyl-l-bromoadamantane and 3,5-dimethyl-1-bromoadamantane are slower than 1-bromoadamantane itself. This result was felt to be inconsistent with any mechanism which distributed positive charge to all bridgehead positions of the adamantyl cation under solvolysis conditions since the introduction of tertiary resonance contributors (cf. Eq. (49)) should enhance rather than retard solvolysis rates 56,164 ... 

Bromination in the absence of free radical catalysts, for example, gives high yields of 1-bromoadamantane (Eq. (53)) 18s The Koch 189> and Ritter 188> 19°) reactions, which involve the initial generation of the 1-ada.-mantyl cation either by means of hydride transfer to the t-butyl cation or... 

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