Potassium cyanide, labelled with isotopic

The need for C-labeled analogues of DALA for the elucidation of biosynthetic and metabolic pathways towards heme and chlorophyll in living cells led to the development of other synthetic routes. The reaction of succinoyl chloride monoesters with C-labeled potassium cyanide provided a straightforward route towards acyl cyanides that are convenient precursors for DALA (24-27). More recently, a versatile and efficient syntheses of C-4-, C-5- and N-DALA was reported (28). The pathway for these syntheses was based on a chain elongation of isotopically labeled glycines. 

Multiple labelling with both stable and radioactive isotopes offers the advantage of simultaneous labelling in the same position of a molecule [68]. The combination of C- and C-labelling combines ease of detection with rapid structural identification. The adoption of this technique in studies of some aspects of the metabolism of 4-morpholino-2-piperazinothieno [3,2-d] pyrimidine (V-K 774) (3) in the rat has been reported [69]. Potassium [ C, C]thiocyanate was prepared from a mixture of potassium [ C, C]cyanides. Reaction with ethyl bromide and methyl 3-aminothiophen-2-carboxylate (4) afforded the thienopyri-midine (5), which, by a series of reactions was converted to V-K 774 (3) labelled in the position shown. 

Sugars enriched with carbon isotopes have been prepared by reaction of aldoses with labelled potassium cyanide, the epimeric aldononitriles being hydrogenated over palladium-barium sulphate to yield the epimeric alditolylimines. The latter spontaneously... 

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