Process for the preparation of hyperpolarized carboxylate compounds

A Para-Hydrogen Induced Polarization process for the preparation of an [1-13C]-hyperpolarized carboxylate containing molecule comprising hydrogenating with molecular para-hydrogen an unsaturated alkenyl or alkynyl ester of said carboxylate containing molecule of formula (II)

• R—C*(O)—O—R′ (II)
• in which:
• C* denotes the naturally 13C enriched or, optionally, 13C labeled carboxylate carbon atom undergoing 13C hyperpolarization;
• R′ is an allyl of formula —CH2—CH═CH2 or a propargyl residue of formula —CH2—C≡CH;
• R is a C1-C5 linear or branched alkyl chain, which is optionally interrupted by, or substituted with, one or more groups selected from the group consisting of carbonyl (—CO—), hydroxyl (—OH), amino (—NHR1), halogen atom, halo-alkyl group, carbocyclic aliphatic moiety optionally substituted by one or more hydroxyl groups, and aromatic moiety optionally substituted by one or more hydroxyl groups;
• and
• R1 is H or an amino protecting group, or a physiologically acceptable salt thereof.