Adamantane dehydro

Dehydrofluorination of compounds in which a single hydrogen is flanked by heavily fluonnated groups is achieved by aqueous or alcoholic alkali hydroMdes and proceeds probably by the ElcB mechanism Thus 1 -(2//-hexafluoropropyl)ada-mantane [75] and 1,3 bis(2//hexafluoropropyl)adamantane [16] sire dehydro-fluorinated in respective yields of 75 and 81% (equation 14)... 

While ring closure reactions of the adamantane nucleus have not yet been reported for the preparation of substituted dehydroadamantanes, direct synthesis of 8,9-dehydro-2-adarmntanone has been accomplished as summarized in Scheme 14 1351. 

Superelectrophilic onium dications have been the subject of extensive studies and their chemistry is discussed in chapters 4-7. Other multiply charged carbocationic species are shown in Table 2. These include Hogeveen s bridging, nonclassical dication (14)26 the pagodane dication (15)27 Schleyer s l,3-dehydro-5,7-adamantane dication (16)28 the bis(fluroenyl) dication (18)29 dications (17 and 19) 19a trications (20-21)19a,3° and tetracations (22-23).31 Despite the highly electrophilic character of these carbocations, they have been characterized as persistent ions in superacids. 

While cation 55 was discovered almost by chance, the dicationic species 57 was prepared by deliberate efforts. Theoretical analysis of the specific configuration of the orbitals at the bridgehead carbons of the adamantane framework encouraged these studies. The analysis predicted a very substantial degree of stabilization for 57, owing to the possibility of efficient overlap of all four orbitals of the bridgehead carbons inside the adamantane cavity. After some searching for an appropriate precursor, it was established that l,3-dehydro-5,7-... 

Selective chlorination. DCU when activated by light converts cyclohexane to chlorocyclohexane in high yield. The reagent also converts adamantane into 1-chloroadamantane. A more useful reaction is chlorination of steroids at Cq to give, after dehydrochlorination with AgClOi, 9(1 l)-dehydro derivatives (equation 1),... 

The structures and NMR chemical shift properties of a series of 1,3-dehydro-sila-adamantane dications, 118-121, have been calculated by DFT methods <2003JA15507, 2002JOC8721>. The cations are found to exhibit three-dimensional heteroaromaticity and indicate that there is significant positive charge at the Si centers. Related results have been obtained for the germanium analogue of 121 <2003JA15507>. 

Table 9 was compiled from work on methyldecalin steroids , tetracyclic compounds, propellanes cyclopropane fused bicyclo[2,2.2]octanes , cyclopropanodecalins tricyclooctanes , homoadamantanes, 1,3-dehydroadamantanes , 2,4-dehydro-adamantanes and diamantanes. ... 

Ketone (174) acts as a precursor to 7,7-disubstituted bic clo[2,2,l]heptanes, the initial step in the sequence involving cleavage of the cyclopropane ring to give (175). Analogous processes have been used in the conversion of 8,9-dehydro-adamantan-2-ones to 2-exo-substituted protoadamantanones. ... 

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