Carbon-11 labelled analogs of alanine by the Strecker synthesis

Derivatives of alanine, α-[2-sup(11)C]aminoisobutyric acid 1a and α-(N-methyl)-[2-11 C]aminoisobutyric acid 1b were prepared for the in-vivo study of amino acid transport phenomena by positron-emission-tomography (PET). Compounds 1a and 1b were obtained by a Zelinski-Stadnikoff variant of the Strecker α-amino acid synthesis from in-situ formed [11 C]acetone in presence of sodium cyanide and either ammonium sulfate (for 1a) or methylamine hydrochloride (for 1b). The complete preparation required 50 min from the end of [11C]CO2 production, and delivered 1.2 - 2 GBq of labelled product for application (2.4 -4%; not corrected for decay; related to trapped [C]CO2. The specific activity of the labelled products was 16 to 20 GBq·μmol-1. The radiochemical and chemical purity of the preparations was greater than 98%. (Author)