Adamantane ferf-butylation

The reaction of tetrachlorodisilane with chalcogenation reagents is one of the synthetic methods to bis-nor-adamantane or double-decker type compounds. When a solution of di-terf-butyltetrachlorodisilane 66 in THF is refluxed together with one equivalent of lithium sulfide or stirred with lithium selenide at room temperature, the tetra(ferf-butylsilicon)pentachalcogenides 67 and 68, respectively, are formed (Scheme 18)6. Each pentachalcogenide exhibits one resonance of a ferf-butyl group in the H and 13C NMR spectra. Most likely, the bis-nor-adamantane derivatives 69 and 70 are initially formed. Insertion of a sulfur or selenium atom into one of the two strained Si—Si bonds would then lead to the observed products. 

Superacid-catalyzed alkylation of adamantane with lower alkenes (ethene, propene, isomeric butenes) has been investigated by Olah et al.151 in triflic acid and triflic acid-B(0S02CF3)3. Only trace amounts of 1 -ferf-butyladamantane (37) were detected in alkylation with 1- and 2-butenes, whereas isobutylene gave consistently relatively good yield of 37. Since isomerization of isomeric 1-butyladamantane under identical conditions did not give even traces of 37, its formation can be accounted for by (r-alkylation, that is, through the insertion of the ferf-butyl cation into the C—H bond (Scheme 5.22). This reaction is similar to that between ferf-butyl cation and isobutane to form 2,2,3,3-tetramethylbutane discussed above (Scheme 5.21). In either case, the pentacoordinate carbocation intermedate, which may also lead to hydride transfer, does not attain a linear geometry, despite the unfavorable steric interactions. 

If 14 or more carbons are present, the product may be diamantane or a substituted diamantane. " These reactions are successful because of the high thermodynamic stability of adamantane, diamantane, and similar diamond-like molecules. The most stable of a set of C H isomers (called the stabilomer) will be the end product if the reaction reaches equilibrium. Best yields are obtained by the use of sludge catalysts (i.e., a mixture of AIX3 and ferf-butyl bromide or iec-butyl bromide).Though it is certain that these adamantane-forming reactions take place by nucleophilic 1,2-shifts, the exact pathways are not easy to unravel... 

To the best of our knowledge, there is only one example in the literature of a photoaddition reaction influenced by CD and involving two different molecules, that is, the photocycloaddition of 5-X-adamantan-2-ones (X = F, Cl, Br, OH, phenyl, ferf-butyl) with fumaronitrile (Scheme 31) [319]. The reaction performed in p-CD aqueous solution led to a remarkable change in product distribution with respect to that found in isotropic solvent. The syn/anti ratio of the frans-oxetane formed was reversed (Table 23). The effect was maximum with the bulkier substituents and was not observed on addition of a- and y-CD. The rationale is that deep inclusion in the P-CD... 

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