Protoadamantanes adamantanes

Treatment of (736) with bromine at room temperature surprisingly yields (737) in a markedly exothermic reaction. A mechanism is discussed in which formation of a tertiary cation at C-5 followed by adamantane-protoadamantane-adamantane rearrangement is invoked for the initial stages of the reaction. In a projected synthesis of (738) it was found that Wolff-Kishner reduction of (739) gave only pyrazolone (a common reaction in such reduction of P-keto esters) and more vigorous conditions (NaOMe-MeOH-NHjNHj, sealed autoclave at 220 C) gave 1,3-adamantanedicar-boxylic acid as well as the desired material (738). The mechanism for the conversion of (739) into (738) is not clear, but reaction is dependent on both methoxide and... 

Protoadamantanone is a versatile intermediate for the synthesis of not only protoadamantane derivatives,but also 1,2- and 2,4-disubstituted adamantanes, ° 2-substituted noradamantanes," and 4(5)-substituted 4-homoprotoadamantanes. ... 

Catalysis. The isomerization of cyclopropane to propylene and the rearrangement of protoadamantane to adamantane were studied on HY zeolite and samples of materials A and B. 

The rearrangement of protoadamantane to adamantane was studied on HY zeolite and those samples of materials A and B produced by reaction with TMS at 400°C. The catalysts (0.1 gram) were activated at 600°C for 6 hours in vacuo and were transferred to a flow system where the reaction was carried out at 240° C under N2 at atmospheric pressure. The reaction is totally selective, giving 96.7% and 42.5% conversion to adamantane on HY and the A material, respectively, but only 7.2% conversion on the B material. 

Catalytic and Electron Transfer Properties. The isomerization of cyclopropane on HY zeolites activated at temperatures less than 600° C is attributed to catalysis by Bronsted acid sites (12, 13), and the activation temperature for maximum activity was in the range 300°-400°C (13). On the other hand, rearrangement of protoadamantane to adamantane proceeds by hydride ion abstraction at Lewis acid sites (lfy. Materials B, therefore, appear to have good Bronsted activity (Figure 5) and in view... 

Protoadamantanone is a versatile intermediate for the synthesis of not only protoadamantane derivatives,but also 1,2- and 2,4-disubstituted adamantanes, 2-substituted noradamantanes, and 4(5)-substituted 4-homoprotoadamantanes. 4-Protoadamantanone has been prepared by the nitrous acid deamination of 2-amino-l-adamantanol (77%), by aprotic diazo-tization of endo-7-aminomethylbicyclo[3.3.1]nonan-3-one in benzene with an equivalent amount of acetic acid (67%), and by thermolysis of 1-adamantyl hypohalites followed by base-promoted cyclization of the resulting halo ketones (32-37%).In spite of low and erratic yields, the last reaction sequence has provided the most convenient route to the protoadamantanes, since the other two approaches require lengthy syntheses of the starting materials. 

For tricyclo[4.3.1.0 ]decane the following trivial names were introduced in the literature isoadamantane (1968) protoadamantane (1968) isotwistane (1969) and 2(3 - 4)abeo-adamantane (1970) In the present review the name isotwistane will be applied, which until now is exclusively used to describe such 2,7-dihetero-tricyclodecanes. However, one should pay attention to the fact that since 1972 the trivial name iso-twistane is also applied for tricyclo[4.3.1.0 )decanes. 

Best results are generally obtained with chromous chloride initiation (yields as high as 90%) but are generally very similar whatever the initiation process used. In the Cy5/Cy6 case only the Cy5 products are observed except in a very special case in which an adamantane skeleton (Cy6) was formed rather than the more strained protoadamantane skeleton (Cy5). In the Cy5/Cy4 case no cyclized products have been observed in the one case studied. In the Cy6/Cy7 case only Cy6 products are observed, generally in good yield, whatever the initiation, when carboxamido radicals are generated from 7V-chloro-iV-methyl amides. However, with acetamido radicals generated... 

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