Adamantane-2,6-dione

Figure 3.22 Encapsulation of adamantane (left) and adamantane-2,6-dione (right)...

Figure 6-21 The HETCOR spectrum of 4-(methoxycar-bonyl)adamantane-2,6-dione. (Reproduced from H. Duddeck and W. Dietrich, Structure Elucidation by Modern NMR, Steinkopff Verlag, Darmstadt, Germany, 1989, p. 22.)...

Adamantanes. Tetramethyl adamantane-2,6-dione-l,3,5,7-tetracarboxylate heated with hydrazine hydrate and a soln. of Na in methanol 8 hrs. at 240-250° in a steel autoclave adamantane-l,3,5,7-tetracarboxylic acid. Y 80.5-93%. S. Landa and Z. Kamy ek, Coll. 24, 4004 (1959). 

Hickmott and coworkers have shown that the reaction of crotonoyl chloride with the pyrrolidino enamine of 4-benzoyl-4-methylcyclohexanone 117 gives a mixture of the three adamantane dione derivatives 118, 119 and 120 (equation 21). Surprisingly the main product obtained was the sterically most crowded 119, with the 6-phenyl and 9-methyl in mutually 1,3-diaxial position. This could be explained if the [3,3] sigmatropic rearrangement of 121 to 122 occurs via a boat transition state conformation from the same face of the cyclohexene moiety as the benzoyl group (equation 22). Although a boat conformation (125 126) normally is preferred for this type of rearrangement,... 

Dimerization and condensation of pentane-2,4-dione by molybdenum(VI) oxide tetrachloride (MoOC14) affords l,3,5,7-tetramethyl-2,4,6,8-tetraoxa-adamantane, the structure of which is determined by elemental analysis, IR, mass, and PMR spectroscopy.188... 

Similar a,a -annulations were achieved from reaction of oc,/ -unsaturated acid chlorides with cyclic ketone enamines which afforded bicyclo[3.3.1]nonane-2,9-diones41,60 65 or bicyclo[4.3.1]decanones66. In this reaction, 7V-acylation of the enamine 109 occurs as the first step giving 110, followed by a [3,3] sigmatropic rearrangement to a ketene intermediate (111). Ketene 111 subsequently cyclized via 112 to a bicyclic immonium salt (113) which after hydrolysis gave the corresponding dione 11463. If there is an axially oriented electrophilic substituent at C-4 of the enamine (for example, R = COPh) the enolate anion 115 may cyclize to an adamantane derivative 116 (equation 20). 

Pentensaure 2-Methyl-2-(2-tetrahydropyranyloxy)- -methylester E21a, 756 (H CH2-CH = CH2) Propansaure 3-(l-Acetoxy-cyclohe-xyl)- -methylester E19a, 803 (R-HgX + En) 2,4,6,8-Tetraoxa-adamantan 1,3,9,9,10,10-Hexamethyl-E14a/1, 227 (Dion-Dimerisier.)... 

Numerous examples of the preparation of versatile and valuable starting materials are also evident. Current theoretical interest in adamantane is reflected by a convenient procedure for its preparation (p. 8). 2-Cyclopentenone (p. 38) and 2-cyclopenten-1,4-dione (p. 36) are not only useful dienophiles for Diels Alder reactions but also attractive starting materials for a variety of compounds of theoretical interest. Similarly, the preparations of allene (p. 12), tetrolic acid (p. 97), ethylene sulfide (p. 59), and 2-norbornanone (p. 79) provide convenient access to exceptionally useful compounds. 

This can be cyclised in refluxing 62% HBr to an adamantane derivative, the dione 125. The mechanism of this cyclisation is by no means obvious, but with the hint that the alkene 124 is an intermediate and that the stereochemistry of the ester can change by acid-catalysed enolisation, you might see what is going on. 

Wynberg et al. have synthesized the interesting spiro[adamantane-2,l -cyclo-butane-2, 3 -dione] (8) from methyl 2(2-methoxycarbonyladamantyl)acetate (6) by acyloin condensation in the presence of trimethylchlorosilane to give the bis(trimethylsiloxy)cyclobutene derivative (7) in 75% yield. The key step, conversion of (7) into (8), was accomplished under non-hydrolytic conditions by addition of bromine to a solution of (7) in carbon tetrachloride.5... 

Successive treatment of bis-3,3-dimethylallenyl sulphone (357) with butyl-lithium in THF at 0 °C gave a 60% yield of the dithia-adamantane (358), whose structure was confirmed by X-ray crystallography. Photolysis of thietans in the presence of a new triplet sensitizer, l,3-dimethyl-2-thioxoimidazolidine-4,5-dione, has produced interesting results for example, the spiro-xanthone (359) gave the acetate (360), but in u.v. light, and without the sensitizer, the thiopyran (361) was obtained in addition to (360). Among several flavonoids identified in a Chinese plant. Euphorbia lunulata Bge., which is used in the treatment of... 

Spiro-0,N-heterocycIics, Excess oxalyl chloride added dropwise to a stirred ice-cooled suspension of adamantane-1-carboxamide in methylene chloride, and stirring continued ca. 2 hrs. at room temp. crude 2 -(l-adamantyl)oxazoline-4, 5 -dione hydrochloride (Y 55-78%) treated at room temp, with abs. ethanol -> l-ethoxyhomoadamantane-2-spiro-2 -oxazolidine-4, 5 -dione (Y 62%). Also with N-subst. amides s. T. Sasaki, S. Eguchi, and T. Toru, Tetrah. Let. 1968, 4135. 

The MBH reactions of non-enolizable a-diketones precursors (Figure 1.4) with the activated olefins, e.g. acrolein, methyl acrylate and acrylonitrile, have been investigated systematically. The reaction of 3,3,5,5-tetramethyl-cyclopentane-l,2-dione (162) with acrolein and acrylonitrile, but not methyl acrylate, afforded the mono-a-hydroxyalkylation products in high yields. Other nonenolizable a-diketones, such as camphorquinone (159), homo-adamantane-2,3-dione (160) and bicyclo[ 3.3.2]decane-9,10-dione (161) reacted only with acrylonitrile, probably due to the hindered nature of the a-dicarbonyl compounds and the difference in steric demand between nitrile and ester. 

Spiro [adamantane-2,1 -cyclobutane-2, 3 -diones] Cyclobutane-l,3-diones... 

CaHi203, 3-Methyl-2,4,10-trioxa-adamantane, 46B, 306 CaHi20ft, 5-Ethyl-2,2-dimethyl-1,3-dioxane-4,6-dione, 45B, 327 CaHi3CIO6, 2-Methyl-4,5-tetramethylene-1,3-dioxolan-2-ylium perchlorate, 42B, 62... 

Bromine added to a soln. of the startg. bis(trimethylsiloxy)cyclobutene deriv. in CCI4 spiro[adamantane-2,r-cyclobutane-2, 3 -dione]. Y almost 100%. F. e. s. H.Wynberg, S.Reiffers, and J. Strating, R. 89, 982 (1970) Synthesis 7977,209,211. 

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