N-15 Magnetic Resonance Hyperpolarization via the Reaction of Parahydrogen with N-15-Propargylcholine

N-15-Propargylcholine has been synthesized and hydrogenated with para-H-2. Through the application of a field cycling procedure, parahydrogen spin order is transferred to the N-15 resonance. Among the different isomers formed upon hydrogenation of N-15-propargylcholine, only the nontransposed derivative contributes to the observed N-15 enhanced emission signal. The parahydrogen-induced polarization factor is about 3000. The precise identification of the isomer responsible for the observed N-15 enhancement has been attained through a retro-INEPT (N-15-H-1) experiment. T-1 of the hyperpolarized N-15 resonance has been estimated to be ca. 150 s, i.e., similar to that reported for the parent propargylcholine (144 s). Experimental results are accompanied by theoretical calculations that stress the role of scalar coupling constants (J(HN) and J(HH)) and of the field dependence in the formation of the observed N-15 polarized signal. Insights into the good cellular uptake of the compound have been gained.