Adamantane carboxylation

Dichloroquinoxaline gave 2-adamantyl-3-chloroquinoxaline (1-adamantane-carboxylic acid, AgN03, ( 4)28203, MeCN-H20, A, 80°C, 2h 47%). ... 

Rhodopsin is a seven ot-helix trans-membrane protein and visual pigment of the vertebrate rod photoreceptor cells that mediate dim light vision. In this photoreceptor, retinal is the chromophore bound by opsin protein, covalently linked to Lys296 by a Schiff base linkage. Kpega et al.64 have studied NMR spectra of Schiff bases being derivatives of all-frans retinal and amino-p-cyclodextrins as a model of rhodopsin, where p-cyclodextrin plays a role of a binding pocket. On the basis of analysis of the chemical shift differences for the model compound in the presence and in the absence of adamantane carboxylate, it has been shown that the derivative of 3-amino-p-cyclodextrin forms dimer in water and retinoid is inserted into p-cyclodextrin cavity [31]. 

Traces of adamantane carboxylic acid also detected. 

Adamantane carboxylic acids 13, CM-/3, Me-p A-reciprocal 66 indirect detection (sodium chromate)... 

E-S Kwak, FA Gomez. Determination of the binding of f -cyclodextrin derivatives to adamantane carboxylic acids using capillary electrophoresis. Chromatographia 43 659-662, 1996. 

Conversion of the methyl ester of 1-adamantane carboxylic acid to 1-ada-mantyl dimethylcarbinol (66) by reaction with CH3Mgl followed by dehydration and subsequent hydrogenation provides a convenient route to 1-iso-propyladamantane (66a) 164> 20°). Simmons-Smith cyclopropanation of 1-isopropenyladamantane (67) followed by hydrogenolysis of the cyclopropane ring gives 1-r-butyladamantane (68) 204>. An alternative synthesis... 

Functional group manipulations are equally successful for the preparation of a wide variety of 2-substituted adamantanes. Starting with the methyl ester of 2-adamantane carboxylic acid S7> 2061, 2-t-butyladamantane (71) may be prepared in a manner anlogous to that described above for the synthesis of the bridgehead isomer (Scheme 17) 2M These reactions illustrate the... 

Occasionally, special circumstances permit a simple separation of the products which result from such free radical substitutions. Thus, chlorocarbonyl-ation of adamantane followed by a methanolic work-up (Eq. (66)) results in a nearly 1 1 ratio of 1- and 2-methyl adamantane carboxylates which may be separated readily by fractional distillation206). 

Table IS. Acidities of alkyl substituted adamantane carboxylic acids (see also Ref.4))...

Similar results are obtained when 19-nortestosterone and related androgens 346> as well as various nucleosides347 are esterified with adamantane carboxylic acids. Whereas 107 exhibits a long duration of myotropic activity coupled with significantly reduced androgenicity, the 3-methyl and 3,5-di-... 

Substituted adamantanes have been employed in the study of several reaction mechanisms. The Kolbe electrolyses of 1- and 2-adamantane carboxylic acids and 1- and 2-adamantyl acetic acids have been compared in detail. Car-bonium ion-derived products are observed from the electrolyses of both 1-adamantyl carboxylic acid and 1-adamantyl acetic acid. A mixture of radical and carbonium ion-derived products are obtained from 2-adamantyl carboxylic acid and mainly radical-derived products are obtained from 2-adamantyl acetic acid. These results parallel the known or expected stabilities of the intermediate carbonium ions 366 ... 

A suspension of betamethasone (740.0 mg) in dioxan (20 ml) was treated with adamantane carboxylic acid (1.96 g) and trifluorcacetic anhydride (0.75 ml). The mixture was stirred at room temperature for 23 h during which time the steroid completely dissolved. Addition of sodium bicarbonate (2.0 g) and water gave a waxy semi-solid which was separated from the supernatant liquid by decantation. Water and a little methanol were added to the solid and the resulting granular material was removed by filtration and washed well with water. Fractional crystallization from methanol afforded adamantane carboxylic anhydride as the less soluble component and betamethasone 21-adamantane-l -carboxylate as the more soluble component. 

Fig. 1. Topographies of cyclodextrin inclusion complexes a-CD - nitromethane (75) (top), p-CD - adamantane-carboxylate (76, 77) (center), and y-CD - 12-crown-4 (76, 78). The striking correspondence of hydrophobic surface regions of guest and CD-host at their interfaces may be viewed in color on the Internet (79).

Figure 33 Structures of (a) pivalic acid (b) 2,2-dimethylbutyric acid and (c) 1 -adamantane carboxylic acid.

PpyFess Pt(acac)2, Fe(CO)5 hexadecyl amine 1-adamantane- carboxylic acid 350-360 8 85, 86... 

Cinnamoyl- 6-CD (6-CiO-/3-CD) was sparingly soluble in water, although most 6-substituted 6-CDs are soluble. However, 6-CiO-/3-CD was solubilized in water on the addition of adamantane carboxylic acid or p-iodoaniline which could be included in a 6-CD cavity. These results suggest that 6-CiO-/l-CD formed supramolecular polymers in the solid state, as shown in the proposed structure in Fig. 17. The X-ray powder pattern of 6-CiO-/l-CD was similar to that of the complex between p-CD and ethyl cinnamate, in which /3-CDs formed a layer structure. The crystal structure of 6-aminocinnamoyl-/3-CD (6-aminoCiO-/l-CD) is shown in Fig. 12 and we discussed the relationship between crystal packing and the substituent group in Sect. 2.8. 

A nano-sized three-dimensional supramolecule 50a self-assembled quantitatively from six molecules of la and four molecules of tridentate ligand 41 (Scheme 18). The complex 50a is a thermodynamically stable product because the formation of the product is not affected by the presence of excess of la. The structure of the clatharate complex of 50a with the adamantane carboxylate ion was determined... 

Figure 10. The nanosized aggregate in the crystal structure of 50a-(adamantane carboxylate)4. (a) The host framework, (b) A space-filling representation showing the small entrance.of nanosized cavity.

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