Efficient Synthesis of Molecular Precursors for Para‐Hydrogen‐Induced Polarization of Ethyl Acetate‐1‐ 13 C and Beyond

A scalable and versatile methodology for production of vinylated carboxylic compounds with 13 C isotopic label in C1 position is described. It allowed synthesis of vinyl acetate‐1‐ 13 C, which is a precursor for preparation of 13 C hyperpolarized ethyl acetate‐1‐ 13 C, which provides a convenient vehicle for potential in vivo delivery of hyperpolarized acetate to probe metabolism in living organisms. Kinetics of vinyl acetate molecular hydrogenation and polarization transfer from para‐hydrogen to 13 C via magnetic field cycling were investigated. Nascent proton nuclear spin polarization (% P H ) of ca. 3.3 % and carbon‐13 polarization (% P 13C ) of ca. 1.8 % were achieved in ethyl acetate utilizing 50 % para‐hydrogen corresponding to ca. 50 % polarization transfer efficiency. The use of nearly 100% para‐hydrogen and the improvements of % P H of para‐hydrogen‐nascent protons may enable production of 13 C hyperpolarized contrast agents with % P 13C of 20–50 % in seconds using this chemistry.