Über Verbindungen mit Urotropin‐Struktur, XVIII. Über die Bromierung des Adamantans

Abstract

Raumtemperatur; nach 2 Stdn. wurde 1 m Aceton zugefllgt. Nach 10 Stdn. wurden noch 0.05 g festes NaHCO3 sowie 0.15 g Dinitrofluorbenzol in 1 ccm Aceton zugegeben und weitere 3 Stdn. geriihrt. Mit 7.0 ccm Wasser fie1 das Produkt in bldgelben Flocken aus. Es rmrdc abgesaugt und mit 50-proz. Methanol und Wasser gewaschen, sodann 3 mal mit je 20 ccm heiBem Methanol extrahiert; aus dem Filtrat wurden 0.29 g groDe blaDgelbe Rhomben erhalten. Schmp. Dieselbe Substanz wird durch Oxydation von Coniferylalkohol-ditrophenylather rnit Braunstein erhalten. 1 .OO g Coniferylalkohol-dinitrophenylilther 20) wurde in 55 ccm trokkenem Aceton gelbst und mit 70 ccm Tetrachlorkohlenstoff versetzt. Nach Zugabe von 10.0 g MnOz wurde geriihrt. Withrend der Oxydation rmrden im Abstand von 15 Min. Proben entnommen und im Gemisch I chromatographiert; sie zeigten, daB die Oxydation bereits nach 1/4 Stde. vollstitndig war. Nach 1 Stde. rmrde von MnOz abzentrifugicrt. dieses mit Aceton/ Tetrachlorkohlenstoff gewaschen, die Lbsung filtriert und i. Vak. unter Stickstoff eingedampft. Ausbeute 90% d. Th. Anriihren rnit wenig Methanol fllhrte zur Witallisation. Zweimalige verlustreiche Umkristallisation aus 50 ccm warmem Methanol lieferte blaDgelbe Prismen vom Schmp. 159-160" (Mischprobe). CpjH12N207 (344.3) Ber. C 55.81 H 3.51 OCH3 8.14 Gef. C 55.72 H 3.62 OCH3 8.19 R,-Werte: In Gernisch I 0.71 ; in Cyclohexan, mit Dimethylformamid halb gesilttigt, 0.73. Die IR-Spektren der auf beiden Wegen gewonnenen Prgparate sind identisch. 1) XVII. Mitteil.: H. STETTER und E. RAUSCHER, Chem. Ber. 93, 1161 [1960]. 2) H. STETTER, M. SCHWARZ und A. HIRSCHHORN, Chem. Ber. 92, 1629 [1959].

Functionalized Nanodiamonds Part I. An Experimental Assessment of Diamantane and Computational Predictions for Higher Diamondoids

“…The increasing stabilities of tertiary cations enhance the reactivity of the higher diamondoids relative to adamantane under ionic conditions: triamantane reacts with bromine at 0 8C rapidly, [25] whereas the bromination of adamantane requires a longer reaction time or substantial heating. [21] Diamondoidyl radicals: The correlation of the relative stabilities of hydrocarbon radicals with the selectivities in CÀH substitution reactions is often crude because hydrogen-atom abstractions are mostly entropy-controlled. [17,35] We also computed all possible isomeric tertiary radicals derived from compounds 1-7; the B3LYP/6-31G* DH 298 values vary only in the range of 1 kcal mol…”

“…These reactions are mechanistically neither radical [17] nor purely electrophilic in nature, [18] and instead proceed through H-coupled electron-transfer pathways. [19,20] As there is only one type of tertiary CÀH bond in adamantane, it reacts selectively with neat Br 2 , [21] ICl, [22] and 100 % HNO 3 , [23] making many tertiary adamantane derivatives available in high preparative yields, even on industrial scale. Selective functionalization of diamantane with electrophiles gives medial tertiary C 1 derivatives; apical C 4 derivatives can only be obtained indirectly.…”

Preparation and Reactivity of [D3d]‐Octahedrane: The Most Stable (CH)12 Hydrocarbon

“…This is remarkable, since hydrogenolysis of oligocyclic hydrocarbons with more than one cyclopropane moiety does not necessarily occur with thermodynamic control, as had previously been hypothesized, [25] but may be governed by the mode of adsorption on the catalyst surface. [26] Direct functionalizations of several cage hydrocarbons, especially adamantane (12), with electrophilic (bromination, [27] nitroxylation [28] ) or radical (halogenation, [29] oxygenation [30] ) reagents have been studied. Bromination of the structurally related hydrocarbon diamantane 11 occurs at the "belt" C-H position under mild conditions.…”

Rigid C3‐Symmetric Scaffolds Based on Adamantane

“…Selectivity is therefore often not a problem and protocols, for example, for the selective introduction of one, two, three or four bromine atoms at the adamantane bridgeheads are well known and give all four different adamantyl bromides in good yields. [21] However, as a general trend, substitutions get more difficult with the number of electron-withdrawing substituents attached to the bridgehead positions due to statistical and electronic effects. [22] Consequently, methods for the generation of tri-or tetrasubstituted adamantanes are often not compatible with functional groups, such as amines, alcohols, carboxylic acids or alkynes.…”