Adamantane carbonylation

A solution of betamethasone (1.0 g) in dry tetrahydrofuran (40 ml) was treated with adamantane carbonyl chloride (about 2.2 equivalents) in dry tetrahydrofuran (5 ml) and then pyridine (0.8 ml) was added. The mixture was refluxed for 6 h and then most of the solvent was boiled off and the residue extracted with chloroform to afford a froth. The ether soluble portion of this froth was dissolved in chloroform and extracted repeatedly with dilute sodium bicarbonate solution. Evaporation of the chloroform layer gave a froth which was further purified by chromatography and crystallisation from chloroform-petroleum ether to yield betamethasone 21-adamantane-l -carboxylate melting point 256°-259°C (dec.). 

Tetraorganosilanes having an unsaturated organic group yield adamantyl ketones if they react with I-adamantane carbonyl chloride [589] (Eq. 4.48) ... 

Activator 1-Adamantane carbonyl chloride in 1 1 Pyridine/acetonitrile 70 g/L for scales up to 300 LUnol 140 g/L for scales more than 300 pmol Activator reservoir... 

The carbonyl n face of the adamantan-2-one with an electron-withdrawing group at the 5-position is nnsynunetrized by interaction of the P o bonds antiperiplanar to the C-H bonds and to the C-R bond. The orbital phase environment of the carbonyl n orbital (7) is nnsynunetrized by the more electron-donating orbitals at the P-position, which is consistent with the observed syn preference. 

This reviews contends that, throughout the known examples of facial selections, from classical to recently discovered ones, a key role is played by the unsymmetri-zation of the orbital phase environments of n reaction centers arising from first-order perturbation, that is, the unsymmetrization of the orbital phase environment of the relevant n orbitals. This asymmetry of the n orbitals, if it occurs along the trajectory of addition, is proposed to be generally involved in facial selection in sterically unbiased systems. Experimentally, carbonyl and related olefin compounds, which bear a similar structural motif, exhibit the same facial preference in most cases, particularly in the cases of adamantanes. This feature seems to be compatible with the Cieplak model. However, this is not always the case for other types of molecules, or in reactions such as Diels-Alder cycloaddition. In contrast, unsymmetrization of orbital phase environment, including SOI in Diels-Alder reactions, is a general concept as a contributor to facial selectivity. Other interpretations of facial selectivities have also been reviewed [174-180]. 

Olah and coworkers" also prepared the diaeyl dieations involving the adamantane framework. The ionization of the bis-1,3-adamantanediearbonyl chloride, 96, in SbFs/ SO2CIF at -80°C gave the corresponding 1,3-adamantanedicarbonyl dication, 97. The carbonyl carbons of the dication (8 C 147.5) show shielded C NMR absorptions... 

Tris[(2-perfluorohexyl)ethyl]tin hydride has three perfluorinated segments with ethylene spacers and it partitions primarily (> 98%) into the fluorous phase in a liquid-liquid extraction. This feature not only facilitates the purification of the product from the tin residue but also recovers toxic tin residue for further reuse. Stoichiometric reductive radical reactions with the fluorous tin hydride 3 have been previously reported and a catalytic procedure is also well established. The reduction of adamantyl bromide in BTF (benzotrifluoride) " using 1.2 equiv of the fluorous tin hydride and a catalytic amount of azobisisobutyronitrile (AIBN) was complete in 3 hr (Scheme 1). After the simple liquid-liquid extraction, adamantane was obtained in 90% yield in the organic layer and the fluorous tin bromide was separated from the fluorous phase. The recovered fluorous tin bromide was reduced and reused to give the same results. Phenylselenides, tertiary nitro compounds, and xanthates were also successfully reduced by the fluorous fin hydride. Standard radical additions and cyclizations can also be conducted as shown by the examples in Scheme 1. Hydrostannation reactions are also possible, and these are useful in the techniques of fluorous phase switching. Carbonylations are also possible. Rate constants for the reaction of the fluorous tin hydride with primary radicals and acyl radicals have been measured it is marginally more reactive than tributlytin hydrides. ... 

Adamantanecarboxylic acids with a carboxylic group at a bridgehead position, e.g. adaman-tane-1-carboxylic acid (8),111 react with sulfur tetrafluoride in the conventional way giving high yields of the corresponding trifluoromethyl-substituted adamantanes. l-(Trifluoromethyl)-adamantane (9) can also be formed in one step from adamantane by treatment with a mixture of sulfur tetrafluoride, hydrogen fluoride and formic acid the latter serves as a source of carbon monoxide. The reaction is believed to proceed via carbonylation of an intermediate carbocat-... 

Desulfuration of thiols.2 Aromatic, benzylic, and aliphatic thiols are converted into hydrocarbons when heated in acetic acid with molybdenum carbonyl. The bridgehead adamantane-l-thiol is an exception and gives instead a thioester, RSCOCHj. Yields are 50-90%. The actual reagent is probably tetrakis(acetato)-dimolybdenum.3 Molybdenum carbonyl deposited on silica can also be used. 

Oxygenation of 2-substituted adamantanes with methyl(trifluoromethyl)dioxirane showed a reaction constant, p = -2.31, consistent with a strongly electron-demanding transition state. Analysis of the effect of solvents on the rate yielded a positive regression coefficient with Dimroth-Reichardt Ej solvent polarity parameter. A mechanism involving an electrophilic O atom insertion has been postulated for the formation of alcohols and carbonyl compounds.201... 

Scheme 6.7. Concomitant carbonylation and hyperbranched polyaramide formation. Rigid, tetrahedral, adamantane-based cores provided enhanced solubility characteristics.

Figure 10 Conformation of (a) 2-methyl-2-benzoyl adamantane and its complex with Li+ as computed at RB3LYP/6-31G(d) level. Note that the benzoyl carbonyl is tilted toward one of the two prochiral hydrogens. The distances between the carbonyl oxygen and the prochiral hydrogens are included. The binding energy computed at the RHF/3-21G level is given in parentheses.

Adamantan 4,8-Dioxo-2-methoxy-carbonyl- VII/2b, 1404 1-Benzofuran 4,6-Dimethoxy-2,2-dimethyl-3-oxo-2,3-dihydro-VI/3, 636 Benzol... 

---