Adamantyl halides

The reaction between 2-adamantyl halides and PCl /AlBr yields a mixture of di-2-adamantylphosphinic chloride and bromide together with (1-adamanyl)(2-adamantyl)phosphinic chloride 1-adamantyl halides are already known to afford only 1-adamantylphosphonic acid derivatives. 

DR. BRAUMAN Well, there is good news and bad news. If you take tertiary butyl, you get elimination. We have explored the stereochemistry in other reactions, so we know that these are really backside reactions. If we take something like 2,2,2-bicyclooctyl or adamantyl halides (i.e., bridge-head compounds), they don t react. 

Isoquinoline has been alkylated with tertiary halides such as terf-butyl40 or adamantyl halides.41 Isoquinoline is reduced more easily than the halides and the mechanism is believed to involve alkyl radicals formed by homogeneous electron transfer from the heteroaromatic anion-radical A. ... 

In a very interesting report of Molle and Bauer [7] using adamantyl halides and the hindered ketones hexamethylacetone and adamantanone, they observed no alcohol products when the hindered ketones were mixed with preformed adamantyl lithium at low temperature ( —20 C) in diethyl ether. However, when the ketones and halide were mixed with lithium powder under the same low-temperature conditions, substantial yields of the expected carbinols were isolated. They postulated a surface-mediated radical ion or radical pair reaction with the ketone or the ketyl radical. The reaction of a ketyl with the halide was ruled out because earlier researchers [4] had shown that no carbinol was obtained from the reaction of an alkyl halide and benzophenone ketyl. The authors also did not find any carbinol product when the ketyl of adamantanone was reacted with adamantyl halide. By extending their studies to other homologues of adamantane, the authors concluded that the stability of the cagelike radical species determined the extent to which the radical pathway is favored over the organometallic pathway. 

Reactions of Mg/ with adamantyl halides are among the most unusual to be considered in the recent literature. I-Bromoadamantane (adamantyl bromide, AdBrl has received the most attention [651. 

Fort and Lindstrom have demonstrated that there is no significant difference in the magnitude of the benzene-induced shifts of t-butyl and adamantyl halides. They have suggested on this evidence that in... 

Highly Reactive Calcium for the Preparation of Organocalcium Reagents Preparation of 1-Adamantyl Calcium Halides and Their Addition to Ketones. 

Adamantylation of benzotriazole represents a special case because direct substitution in adamantanyl halides by an Sn2 mechanism is impossible, and an SnI mechanism is improbable. In this case, reactive cation 91 is generated by oxidative cleavage of the C-I bond in 1-iodoadamantane 90. Benzotriazole added to the reaction mixture binds cations 91 to afford a mixture of benzotriazol-l-yl 92 and -2-yl 93 derivatives in a ratio of 26 74 and the total yield of 67% (Scheme 5) <2001RJ01762>. 

R. D. Rieke, T.-C. Wu, and L. 1. Rieke 147 HIGHLY REACTIVE CALCIUM FOR THE PREPARATION OF ORGANO-CALCIUM REAGENTS PREPARATION OF 1-ADAMANTYL CALCIUM HALIDES AND THEIR ADDITION TO KETONES 1 -(1 -ADAMANTYLJCYCLOHEXANOL... 

The development of these various solvent parameters and scales has been accompanied by the realization that there are uncertainties in the physical property of the solvent that is correlated by a particular parameter in cases where systematic changes in solvent structure affect several solvent properties. Consider a reaction that shows no rate dependence on the basicity of hydroxylic solvents, and a second reaction that proceeds through a transition state in which there is a small transition state stabilization from a nucleophilic interaction with the hydroxyl group. The rate constants for the latter reaction will increase more sharply with changing solvent nucleophilicity than those for the former, and they should show a correlation with some solvent nucleophilicity parameter. This trend was observed in a comparison of the effects of solvent on the rate constants for solvolysis of 1-adamantyl and ferf-butyl halides, and is consistent with a greater stabilization of the transition state for reaction of the latter by interaction with nucleophilic solvents. ... 

Treatment of adamantane with aluminum halide catalysts in the presence of nonane or 2,3,5-trimethylhexane results in the formation of a mixture of methylated adamantanes 354f Apparently, the 1-adamantyl cation generated by Lewis acid catalysts can initiate intermolecular alkyl shifts (presumably via attack on olefinic intermediates). 

Silver trinitromethane undergoes addition to adamantyl (Ad) halides,31 methyl iodide, and trinitromethyl iodide (Scheme 1.7).32... 

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