Adamantanes alkylation

Tseng, C.C., Handa, I., Abdel-Sayed, A.N.. and Bauer, L., V-[(Aryl substituted adamantane)alkyl]-2-mercaptoacetamidines, their corresponding disulfides and 5-phosphorothioates, Tetrahedron, 44, 1893, 1988. 

Tnfluoroacetic anhydnde in a mixture with sulfuric acid is an efficient reagent for the sulfonylation of aromatic compounds [44] The reaction of benzene with this system in nitromethane at room temperature gives diphenyl sulfone in 61% yield Alkyl and alkoxy benzenes under similar conditions form the corresponding diaryl sulfones in almost quantitative yield, whereas yields of sulfones from deactivated arenes such as chlorobenzene are substantially lower [44] The same reagent (tnfluoroacetic anhydride-sulfunc acid) reacts with adamantane and its derivatives with formation of isomeric adamantanols, adamantanones, and cyclic sultones [45]... 

Enamine addition to an unsaturated ester, followed by an intramolecular alkylation, provided a facile synthesis of an adamantane bis-/3-ketoester 674). Michael addition of pyrrolidinocycloheptene to other acrylic esters 668) and of other enamines to acrylic acids 675), a chloroacrylonitrile 676), and an unsaturated cyanocarboxamide (577) were reported. 

Haloalkynes (R—C=C—X) react with ArSnBu3 and Cul to give R—C= C—Ar. Acetylene reacts with two equivalents of iodobenzene, in the presence of a palladium catalyst and Cul, to give 1,2-diphenylethyne. 1-Trialkylsilyl alkynes react with 1-haloalkynes, in the presence of a CuCl catalyst, to give diynes and with aryl triflates to give 1-aryl alkynes. Alkynes couple with alkyl halides in the presence of Sml2/Sm. Alkynes react with hypervalent iodine compounds " and with reactive alkanes such as adamantane in the presence of AIBN. ... 

It was mentioned above that even alkanes undergo Wagner-Meerwein rearrangements if treated with Lewis acids and a small amount of initiator. An interesting application of this reaction is the conversion of tricyclic molecules to adamantane and its derivatives. It has been found that all tricyclic alkanes containing 10 carbons are converted to adamantane by treatment with a Lewis acid such as AICI3. If the substrate contains more than 10 carbons, alkyl-substituted adamantanes are produced. The lUPAC name for these reactions is Schleyer adamantization. Two examples are... 

Naturally occurring adamantane is generally accompanied by small amounts of alkylated adamantane 2-methyl- 1-ethyl- and probably 1-methyl- 1,3-dimethyl- adamantane and others [3], Diamantane, triamantane, and their alkyl-substituted compounds are also present in certain petroleum crude oils. Their concentrations in cmde oils are generally lower than that of adamantane and its alkyl-substituted compounds. 

Pioneering work on the desulphonylation of jS-ketosulphones was carried out by Corey and Chaykovsky - . This reaction was part of a sequence which could be used in the synthesis of ketones, as shown in equation (53). The main thrust of this work was in the use of sulphoxides, but Corey did stress the merits of both sulphones and sulphonamides for different applications of this type of reaction. The method soon found application by Stetter and Hesse for the synthesis of 3-methyl-2,4-dioxa-adamantane , and by House and Larson in an ingenious synthesis of intermediates directed towards the gibberellin skeleton, and also for more standard applications . Other applications of the method have also been madealthough it does suffer from certain limitations in that further alkylation of an a-alkyl- -ketosulphone is a very sluggish, inefficient process. Kurth and O Brien have proposed an alternative, one-pot sequence of reactions (equation 54), carried out at — 78 to — 50°, with yields better than 50%. The major difference between the two routes is that the one-pot process uses the desulphonylation step to generate the enolate anion, whereas in the Corey-House procedure, the desulphonylation with aluminium amalgam is a separate, non-productive step. 

Secondary Alkyl Alcohols. Treatment of secondary alkyl alcohols with tri-fluoroacetic acid and organosilicon hydrides results only in the formation of the trifluoroacetate esters no reduction is reported to occur.1,2 Reduction of secondary alkyl alcohols does take place when very strong Lewis acids such as boron trifluoride126 129 or aluminum chloride136,146 are used. For example, treatment of a dichlo-romethane solution of 2-adamantanol and triethy lsilane (1.3 equivalents) with boron trifluoride gas at room temperature for 15 minutes gives upon workup a 98% yield of the hydrocarbon adamantane along with fluorotriethylsilane (Eq. 10).129... 

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... 

Oxygen-centered phosphanides are accessible by hydrolysis of the phospha-nides as shown for the oxygen-centered phosphanide 73 of the formula [Sr40- P(SiMe2Prl)2 6] with an Sr4P6 adamantane-like structure as shown in Eq. (7) [74], The strontium atoms are coordinatively saturated by agostic interactions to the silicon-bonded alkyl substituents. 

Insertion occurs at the respective a-position of the alkyl substituent. Using a 3 1 ratio of CHBr, to substrate. With a trace of l-(2,2-dichloroethoxy)adamantane.d 1- and 4-isomers in a 1.7 1 ratio. + 2,5-bis(dichloromethyl) derivatives (40%). > Insertion into the tertiary CH. 

The reagents RuCl3/Na(Br03) /aq. M Naj(C03) and RuCl3/K3(S30j)/aq. M KOH oxidised activated primary alkyl halides RX to carboxylic acids and secondary alkyl halides to ketones, e.g. 1-bromophenylethane to acetophenone [213]. Stoicheiometrically fran -Ba[Ru(OH)2(0)3]/CF3COOH/(bpy)/CH3Cl3 oxidised alkanes (e.g. cyclohexane, adamantane, n-hexane, ethane) to ketones or acids, perhaps via Ru (0) (bpy)(CF C(O)O) [550]. 

In ahnlicher Weise lassen sich Adamantan und seine Alkyl-Derivate aminieren3,4. 

Furthermore, di- and polychlorination are much less prevalent. Dicarboxylic acids are predominantly chlorinated in the middle of the chain,99 and adamantane and bicy-clo[2.2.2]octane at the bridgeheads100 by this procedure. The reasons for the high to - 1 specificity are not clearly understood.101 Alkyl bromides can be regioselectively chlorinated... 

Tricyclic molecules having 10 carbon atoms are converted to adamantane with Lewis acids. Additional carbon atoms become alkyl appendages ... 

The reaction of adamantane with lower alkenes (ethylene, propylene, and butylenes) in the presence of superacids [CF3SO3H or CF3SO3H—B(0S02CF3)3] shows the involvement of both alkylations.34 In the predominant reaction the 1-adamantyl cation formed through protolytic C—H bond ionization of adamantane adamanty-... 

This process is called direct a alkylation. Even the formation of ferf-butyladaman-tane was observed in the superacid-catalyzed alkylation of adamantane with isobutylene necessitating a highly crowded, unfavorable tertiary-tertiary interaction. This provides further evidence for the a-alkylation reaction, as adamantylation of isobutylene with any subsequent isomerization does not lead to this isomer. 

---