Polyenes deuterium-labelled

We used such an approach in the study of dissociative edep reduction of the p, y-unsaturated alcohols. Specially synthesized deuterated 2,4-pentadienol and its derivatives CH2=CHCH=CHCD2Y, where Y = -OH, -OAc, and -OMe, was taken as a substrate RY [272,273] the deuterium label is necessary to distinguish the 1,5-positions. In contrast to the cases studied earlier (cinnamic alcohol, vitamin A, etc.. Sect. 9.2.2, Natural Polyenes Vitamins A and D, Carotenes, and Porphyrins ), the reaction proceeds here via the symmetric pentadienyl anion [CH2-CH-CH-CH-CD2]. Therefore, two piperylene isomers CH3-CH=CH-CH=CD2 (a) and CH2=CH-CH=CH2-CD2H (h) in the strictly equal amounts could be anticipated as products. However, the preferential formation of one isomer, with the rexp= [a]/ m > 2, was found experimentally. This anomaly was explained by nonequUibrium asymmetric arrangement of anion near the electrode due to the orientation inheritance of the original asynunetric molecule RY. This should lead to the intra-anion... 

Sections I-V of this chapter deal with the syntheses of unsaturated organic compounds playing an essential role in biochemical processes of life. Numerous polyunsaturated compounds have been synthesized in order to elucidate their physiological role, for instance in brain. However, the main impact on permanent searches for new improved methods of synthesis of isotopically labelled dienes and polyenes comes from nuclear medicine and nuclear pharmacy. The deuterium and carbon-13 labelled polyunsaturated compounds are needed as internal standards in mass spectral determinations of very low concentrations of biologically active substances in biological fluids. 

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