Formation of Cyclic Derivatives

Department of Chemical Pathology, Bernhard Baron Memorial Research Laboratories, Queen Charlotte s Chelsea Hospital, London 

Formerly, Department of Biochemistry, King s College, London 

Edited by K. Blau and J. M. Halket 1993 John Wiley Sons Ltd 

Cyclization may also occur as a result of an intramolecular rearrangement, sometimes unintentionally, as in the cyclization of vitamin Dj in the heated injection port of a gas chromatograph [1], which was evident from the appearance of unexpected extra peaks. Condensation or polymerization reactions may also lead to cyclic derivatives, for example the formation of diketo-piperazines from dipeptide esters or the production of paraldehyde from three molecules of formaldehyde. However, this chapter is mainly concerned with the deliberate formation of a cyclic derivative, most often by a bridging type of reagent ( bidentate ligand ), and the emphasis will be on analysis and quantitation by 

The requirements for a satisfactory derivatization to a cyclic derivative are set out in Table 1. Apart from the first three, the rest are common to derivatization procedures for chromatography. 

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Two functional groups in the molecule of amino acids offer the possibility of the formation of cyclic derivatives. On combining two molecules of the same amino acid, diketopiperazines are produced [264] (Scheme 5.25). With amido groups present in the... 

For many purposes, such as formation of cyclic derivatives of glycols, vicinal cis groups attached to the cyclopentane ring may be considered to... 

Intramolecular addition of lithiodithiane to an acetal leads to the formation of cyclic derivatives (equation 35). Carbonyl additions have been extended to the analogous imonium salts (R2 —+NR2), which furnish a-amino ketones. °... 

The result obtained for the THE substrate inspired us to design strategies implicating the formation of cyclic derivatives. Of particular interest were compounds... 

The observed general predominance of cis addition products following the carbopalladation step (Schemes la and 2) and the formation of cyclic derivatives (Scheme lb) appear to argue in favor of a mechanism involving a syn addition of the organic residue and the palladium moiety to the carbon-carbon triple bond. The appearance of final products as trans derivatives is more likely to indicate the intermediacy of cis -adducts capable of isomerization to the tran -adducts (Scheme 3) rather than the existence of a direct trans addition paralleling the cis addition pathway. 

Compared with esterification procedures, the formation of cyclic derivatives, as ]ust described, has certain advantages (a)... 

In suitable cases, the formation of cyclic derivatives can provide mass spectra suitable for measurements by El which would normally require the more expensive and less readily available negative Cl technique. The El, Cl and NICI mass spectra obtained from the spiro-cyclic derivative formed on gas chromatography of the... 

Reactions involving the phosphorus halides, ammonia and the phosphazene halides are complex the products depending very much on the reaction conditions. A slight excess of NH4CI in Equation 7.320, for example, favours the formation of cyclic derivatives whereas excess of PCI5 leads to a higher proportion of chain material. The distribution between cyclic and linear products is also affected by the presence of certain metal halides. 

The formation of cyclic derivatives is believed to occm via short-chain linear cations, and the cyclic trimer and tetramer have been obtained directly from the reaction of such cations with ammonium chloride. 

Zalkin VG, HaUcet JM. Derivatization in mass spectrometry, 4. Formation of cyclic derivatives. Eur J Mass Spectrom 2004 10 555-68. 

Zaikin, V.G. Halket, J.M. Derivatization in Mass Spectrometry 4. Formation of Cyclic Derivatives. Eur. Mass Spectrom. 2004,10, 555-568. 

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