USOO7470813B2 (12) United States Patent (10) Patent No.: US 7470,813 B2 Gloegaard et al. (45) Date of Patent: Dec. 30, 2008 (54) METHOD FOR THE PRODUCTION OF WO 2006/011810 2, 2006 PYRUVIC ACID WO 2006/O54903 2, 2006 WO 2007/069909 6, 2007 (75) Inventors: Christian Gloegaard, Oslo (NO); Tom WO 2007 111515 10/2007 (73) Assignee: GE Healthcare Limited, Amersham R.W. Friesen, J. Chem. Soc., Perkin Trans. 1, 2001, 1969-2001.* (GB) Friesen, Richard, “Generation and reactivity of alpha-metalated vinyl ethers' J. Chem. Soc., Perkin Trans. 1, 2001, pp. 1969-2001. (*) Notice: Subject to any disclaimer, the term of this Verkruujsse, H.D., et al. “Convenient procedures for the alpha-metal patent is extended or adjusted under 35 lation of vinylic ethers and thioethers' J. Organomet. Chem, 1987. 332, pp. 99-103. U.S.C. 154(b) by 0 days. Sheng, S. etal. “Polymer-supported beta-bromoethyl selenide: an efficient reagent for the synthesis of aryl vinyl ethers' Synthesis (21) Appl. No.: 12/056,582 2004, No. 17, pp. 2833-2836. Bosch, M. et al., “Synthesis of Allyl and Alkyl vinyl ethers using an (22) Filed: Mar. 27, 2008 in situ prepared air-stable palladium catalyst. Efficient transfer vinylationofprimary secondary and tertiary alcohols' J. Org. Chem. (65) Prior Publication Data 2003, 68, pp. 5225-5227. Taylor, R. “The mechanism of thermal eliminations. Part 26. US 2008/O242889 A1 Oct. 2, 2008 Substituent effects at each carbon of vinyl ethers: non-planarity of the transition state” J. Chem. Soc., Perkin Trans. 1988 pp. 737-743. (30) Foreign Application Priority Data Grobelny, etal. “Electron-transfer reduction of selected alcohols Mar. 30, 2007 (NO) .................................. 2007 1682 with alkalide K-, K+(15-crown-5)2 via organometallic intermedi ates' J. of Organometallic Chemistry, 689, 2004 pp. 2361-2367. Seebach, D. et al., “Generation and synthetic applications of 2-lithio (51) Int. Cl. 1,3-dithianes' J. Org. Chem., vol. 40, No. 2, 1975 pp. 231-237. C07C 59/00 (2006.01) Anker, H.S. “Synthesis of carbonyl-labeled pyruvic acid' J. Biol. (52) U.S. Cl. ...................................................... 562/577 Chem, 176 (1948, pp. 1333-1335. (58) Field of Classification Search ....................... None Shimano, et al., Tetrahedron Lett., 1994, 35 p. 7727-7730. See application file for complete search history. * cited by examiner (56) References Cited Primary Examiner Karl J. Puttlitz U.S. PATENT DOCUMENTS (74) Attorney, Agent, or Firm—Craig Bohlken 4,247,716 A 1/1981 Kiyoura (57) ABSTRACT FOREIGN PATENT DOCUMENTS The invention relates to a method for the production of pyru EP 337246 7, 1992 EP 313.850 1, 1993 vic acid, in particular pyruvic acid that is 'C-enriched at the JP 8183753 T 1996 C1-atom, i.e. "C-pyruvic acid. WO 95,00656 1, 1995 WO 2006/011809 2, 2006 15 Claims, No Drawings US 7,470,813 B2 1. 2 METHOD FOR THE PRODUCTION OF produced during said enzymatic oxidation. Further, an PYRUVIC ACID upscale of enzymatic processes to an industrial process level is often problematic or impossible. Examples for methods FIELD OF THE INVENTION involving the use of microorganisms for the production of 5 pyruvic acid are for instance described in EP-A-313.850. A The invention relates to a method for the production of disadvantage of these microbiological production processes pyruvic acid, in particular pyruvic acid that is 'C-enriched at is that can be difficult and time consuming to separate, isolate the C1-atom, i.e. "C-pyruvic acid. and purify pyruvic acid from the complex reaction mixtures, e.g. form complex fermentation broths. BACKGROUND OF THE INVENTION Examples of chemical synthesis for the production of pyru 10 Vic acid are largely based on the oxidation of various starting Pyruvate, i.e. a salt of pyruvic acid, is an important inter materials like propylene glycol (as described in EP-A-337 mediate in the pathway of carbohydrate metabolism andfatty 246), hydroxyacetone (as disclosed in U.S. Pat. No. 4,247. acid metabolism in the human and animal body. In order to 716) or lactic acid (see for instance.JP-A-8183753). However, gain insight in these metabolic pathways, 'C-isotopically for the production of isotopically enriched C-pyruvic acid, enriched pyruvate (hereinafter C-pyruvate) has been used 15 the use of a commercially available isotopically enriched to detect metabolites of pyruvate generated in the living body starting material or an isotopically enriched starting material by 'C-NMR. that is obtainable by a straightforward chemical synthesis is Further, hyperpolarised "C-pyruvate has been used as greatly preferred. imaging agent in 'C-magnetic resonance (MR) imaging Further, to be used as hyperpolarised MR imaging agent, (MRI) and/or spectroscopy (MRS) for in vivo and in vitro "C-pyruvic acid has to be of highpurity. It is also important 'C-MR studies of metabolic processes in the human and that the synthesis can be upscaled since when the compound animal body. is used as an MR imaging agent, relatively large amounts of The term “hyperpolarised denotes an enhanced nuclear "C-pyruvate need to be injected per dose and hence rela polarisation of the C-nuclei present in the pyruvate mol tively large amounts of "C-pyruvic acid need to be ecule. Upon enhancing the nuclear polarisation of the 'C- 25 polarised. Several methods for the chemical synthesis of iso nuclei, the population difference between excited and ground topically enriched pyruvic acid are known in the art. Seebach nuclear spin states of these nuclei is significantly increased et al., Journal of Organic Chemistry 40(2), 1975, 231-237 and thereby the MR signal intensity is amplified by a factor of describe a synthetic route that relies on the protection and hundred and more. When using hyperpolarised "C-pyruvate, activation of a carbonyl-containing starting material as an as MR imaging agent, there will be essentially no interference 30 S.S-acetal, e.g. 1,3-dithian or 2-methyl-1,3-dithian. The from background signals as the natural abundance of "C is dithian is metallated and reacted with a methyl-containing negligible. Thus the image contrast Will be advantageously compound and/or "CO. By using the appropriate isotopi high. Hyperpolarised "C-pyruvate may for instance be used cally enriched 'C-compound as outlined in this reference, it as an MR imaging agent for in vivo tumour imaging as is possible to obtain 'C-pyruvate, "C-pyruvate or 'C- described in detail in WO-A-2006/011810 and WO-A-2006/ pyruvate which may then be converted into the free acid by 01 1809. Further, it may be used for assessing the viability of 35 methods known in the art. myocardial tissue by MR imaging as described in detail in S. H. Anker et al., J. Biol. Chem.176 (1948), 1333-1335 WO-A-2006/054903. Hyperpolarised "C-pyruvate can be describe a different synthetic route that starts from acetic obtained by for instance dynamic nuclear polarisation (DNP). acid, which is first converted into acetyl bromide and then In this method, "C-pyruvic acid can be hyperpolarised and is reacted with Cu'CN. The nitrile obtained is converted into subsequently converted to "C-pyruvate by using a base for 40 pyruvic acid via the amide. However, the use of toxic cya dissolving the solid hyperpolarised "C-pyruvic acid nides limits the application of this method to Small scale obtained by DNP. Alternatively, "C-pyruvate can be directly production of C-labelled pyruvic acid. used in the DNP process in form of certain salts. The produc We have now surprisingly found a method to produce tion of hyperpolarised "C-pyruvate is described in detail in pyruvic acid and pyruvic acid which is isotopically enriched WO-A-2006/01 1809, in WO-A-2007/069909 and WO-A- 45 at the C1-atom, preferably 'C-pyruvic acid in excellent 2007/11 1515, the latter two applications describing the use of purity. The method is easily upscaled such that lager amounts 'C-pyruvates in the described DNP method. of pyruvic acid or isotopically enriched pyruvic acid can be In the body, pyruvate is converted (metabolised) into dif prepared. Apart from C-enriched pyruvic acid, the method ferent compounds: its transamination results in alanine, via can also be used to produce 'C-enriched pyruvic acid, 'C- oxidative decarboxylation; pyruvate is converted into acetyl 50 pyruvic acid. Such a compound can be used as a tracer in CoA and carbon dioxide (which is further converted to bicar positron emission tomography (PET). bonate), the reduction of pyruvate results in lactate and its carboxylation in Oxaloacetate. DESCRIPTION OF THE INVENTION Hyperpolarised "C-pyruvate which is labelled at the C1-atom, i.e. "C-pyruvate is preferably used as MR imag 55 The invention provides a method for producing pyruvic ing agent since it has a long T relaxation in human full blood acid by (42s at 37°C.), which allows real-time monitoring and detec tion of its conversion to hyperpolarised "C-lactate, hyperpo a) reacting a vinyl ether of formula (I) larised 'C-bicarbonate and hyperpolarised C-alanine by C-MR/NMR. (I) Several methods for the production of pyruvic acid are 60 RO H known in the art which can be grossly divided into methods involving the use of microorganisms or enzymes and chemi cal synthesis. An example of an enzyme based method for the production of pyruvic acid is the enzymatic oxidation of lactic acid, as for 65 wherein instance described in WO-A-95/00656. Enzymatic oxidation R is a straight chain or branched C-C-alkyl group or an often results in byproducts as reactive hydrogen peroxide is aliphatic or aromatic ring comprised of 5-7 carbon US 7,470,813 B2 3 4 atoms, optionally substituted with one or more lower If"C-pyruvic acidis obtained by the method of the inven alkyl groups, halogen groups or nitro groups tion, said 'C-pyruvic acid may be directly used in the DNP with an alkyllithium base to obtain an O-metalated vinyl process to produce hyperpolarised C-pyruvic acid.