Remote functionality introduction

Scheme 6-3 Introduction of double bonds into steroids by remote functionalization.

The introduction of hydroxy and carbonyl groups at unactivated positions of terpenoids is usually accomplished by micro-organisms.35 However, recent studies have shown that rabbits can hydroxylate cedrol (72) at a remote unactivated methylene group to provide a mixture of products (73a and b) and (74a and b).36 Patchoulol (298) has also been functionalized in a similar fashion (c/. p. 90). 

Priihs et al. found an elegant application for a seemingly remote hydroxy group in the sidechain [43]. The remoteness of the hydroxy group implies a mode of introduction to the central imidazole ring different to the epoxide method developed by Arnold (hydroxyethyl) and Thiel (hydroxyhexyl). Indeed, Priihs et al. modilied the classic method of imidazo-lium salt synthesis by using a bromoalkane as carrier for the hydroxy functional group. In this way, they reacted A-mesityl imidazole with l-bromo-ta-hydroxyalkanes to obtain the... 

Automatic specimen introduction requires the development of mechanical interfaces between each laboratory analyzer and devices such as conveyor belts, mobile robots, or robot arms. Enhancements to electronic interfaces for laboratory instruments are necessary to allow remote computer control of front-panel functions, notification of instrument status information, and coordination of the distribution of specimens between instruments. Most existing LIS interfaces with laboratory analyzers provide only the ability to download accession numbers and the tests requested on each specimen, and to upload the results generated by the analyzer. 

This work provides another illustration of the use of the halogen-dance reaction in synthesis, and further evidence that it can be a valuable tool for the functionalization of heterocycles. Perhaps the most useful feature of this reaction is that it allows for the introduction of halogens at remote sites in a that are difficult to access by other means. However, this work also illustrates that this reaction can exhibit certain limitations, some of which are rather unexpected and surprising. Ultimately, as the reaction sees more use in synthesis, its scope will be better defined and it will be easier to gauge the success of the reaction in a particular system. 

Intramolecular hydrogen abstraction by excited nitrobenzene derivatives may lead to the introduction of an oxidized functional group in a remote part of the molecule, as previously reported by Scholl and Van De Mark.63 Japanese workers have now extended this reaction to the preparation of some oxidized derivatives of the triterpene dammaranediol.64... 

In an attempt toward syntheses of betulafolienetriol (13) and 20(5)-protopanaxadiol (26), the genuine sapogenin, introduction of an oxygen function at the unactivated methylene at c-12 of the dammarane skeleton was achieved 128, 129) by means of remote oxidation (130) using a photoexcited aromatic nitro group (131, 132, 133) (see Chart 18). Irradiation of the p-nitrophenyl-acetate (83) of 3-epidammaranediol-II (84)... 

Molecular dynamics characterisations in solids can be carried out selectively using dipolar-dephasing experiments. Aliev and Courtier-Murias have shown that the introduction of a sum of Lorentzian and Gaussian functions greatly improve fittings of the intensity versus time data for protonated carbons in dipolar-dephasing experiments. The Lorentzian term accounts for remote intra- and intermolecular dipole-dipole... 

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