Adamantanones

Many [2 + 2] photocycloadditions have not been assigned a definitive mechanism, but they serve well as synthetic methods. Thiones add vinyl ethers to give thietanes in very good yields (Section 5.14.4.1.2), and interesting wavelength-stereochemistry relations were found in the photoaddition of 2-adamantanone to dicyanoethylene (Section 5.14.4.1.2). Diheterocyclobutanes can also be prepared by [2 + 2] photocycloadditions (Section 5.13.3.3). 

Also due to the high barrier of inversion, optically active oxaziridines are stable and were prepared repeatedly. To avoid additional centres of asymmetry in the molecule, symmetrical ketones were used as starting materials and converted to oxaziridines by optically active peroxyacids via their ketimines (69CC1086, 69JCS(C)2648). In optically active oxaziridines, made from benzophenone, cyclohexanone and adamantanone, the order of magnitude of the inversion barriers was determined by racemization experiments and was found to be identical with former results of NMR study. Inversion barriers of 128-132 kJ moF were found in the A-isopropyl compounds of the ketones mentioned inversion barriers of the A-t-butyl compounds lie markedly lower (104-110 kJ moF ). Thus, the A-t-butyloxaziridine derived from adamantanone loses half of its chirality within 2.3 days at 20 C (73JCS(P2)1575). 

The stabilization reactions of alkylcarbenes were used preparatively in some cases. The diazirine derived from adamantanone gave the dehydroadamantane (2l7) thermally in 96% yield 73ZOR430). Alkene formation was reported for a steroid with its C-3 atom part of a diazirine ring. At 140 °C a A-2-unsaturated steroid was formed 65JA2665). 

Commercial 2-adamantanone (Aldrich Chemical Company, Inc.) was used. 

Adamantanecarbonitrile was prepared previously by a more laborious method, also starting from adamantanone in 46% overall yield. 

Tnfluoroacetic anhydnde in a mixture with sulfuric acid is an efficient reagent for the sulfonylation of aromatic compounds [44] The reaction of benzene with this system in nitromethane at room temperature gives diphenyl sulfone in 61% yield Alkyl and alkoxy benzenes under similar conditions form the corresponding diaryl sulfones in almost quantitative yield, whereas yields of sulfones from deactivated arenes such as chlorobenzene are substantially lower [44] The same reagent (tnfluoroacetic anhydride-sulfunc acid) reacts with adamantane and its derivatives with formation of isomeric adamantanols, adamantanones, and cyclic sultones [45]... 

The reaction of tnflic acid with 2-hydroxy-2-adamantanecarboxylic acid results in decarbonylation to adamantanone [84] However, in the presence of carbon monoxide, the same reactants give 4,3 homoadamantanedione as the product of a pinacolone-type rearrangement (equation 35)... 

Scheme 123 Experimental conditions (i) Ag02CPh, THF (b) 2-adamantanone (iv) C3H5MgCl, THF. ...

Strain can exert other influences on molecules. l-Aza-2-adamantanone (100) is... 

The carbonyl n orbital is also assumed to be unsymmetrized arising from the out-of-phase interaction of the orbital attached to the more electron-donating aryl group (9 and 10). These unsymmetrizations of the carbonyl k orbital correspond well to syn addition (9) and anti addition (10), respectively. Thus, the electron-donation of the p-a orbitals controls the facial selectivities. The cyclopentane system was more sensitive to stereoelectronic effects, showing larger induced biases, than the adamantanone system [63]. 

Free intermediate thioaldehydes 598 or 602 and the selenoaldehydes 605 and HMDSO 7 are obtained in THF at 0°C on treatment of aliphatic and aromatic aldehydes with bis(trimethylsilyl)thiane 601 or bis(trimethylsilyl)selenide 604 in the presence of traces of butyllithium, while trapping the sensitive intermediate thio- or selenoaldehydes 602 and 605 with cyclopentadiene or cyclohexadiene to furnish mixtures of endo and exo Diels-Alder adducts such as 603 a and 606 a and 603 b and 603 b [148-150], the exo/endo ratio of which can be controlled [150] (Scheme 5.48). Analogous reaction of ketones such as 2-adamantanone or acetylene ketones with MesSiXSiMes 608 (a. X=S (601) b. X=Se (604)) in the presence of... 

Section C of Scheme 10.15 shows some Schmidt reactions. Entry 14 is a procedure using polyphosphoric acid, whereas Entry 15 was done in H2S04. Entry 16 is a case of conversion of a cyclic ketone, adamantanone, to the corresponding lactam. 

Typical preparation of naphthopyran 32 involves Fries rearrangement of 1-acetoxynaphthalene 30. Condensation of 2-acetyl- 1-naphthol 31 with adamantanone, followed by usual reduction and dehydration gives 32 (Scheme 16).70... 

In the present study isomorphic substitution of Al with Sn [11-13] in the silicalite framework was attempted in order to induce catalytic functionalities and these catalysts was studied for Baeyer-Villiger oxidation of 2-adamantanone and norboranone. 

Moderately sterically hindered adamantanone and bicyclo[3.3.1]nonan-9-one give the corresponding cycloadducts. 

Table 1 Selected structural and spectroscopic properties of /V-acyloxy-iV-alkox yam ides 31b and 31f, -urea 38i, -carbamate 39g, theoretical models 40 and 41 and 1-aza-2-adamantanone 1...

Crystal data for all four amides are uniformly similar. While amides 31b and 31f (IXnI = 65.6° and 65.3°, respectively) are more pyramidal than the urea and carbamate (IxnI = 57.1° and 56.3°, respectively) all four possess sp3-hybridised nitrogens. Average angles at nitrogen for the two amides are smaller than that required by pure tetrahedral geometry as exemplified by the tetrahedral nitrogen in l-aza-2-adamantanone 1. 

---