Site-selective and metal-free aliphatic C-H oxidation enabled synthesis of [5,24,25-D3]-(25S)-Δ(7)-dafachronic acid.

Steroid hormones play significant roles in both worms and mammalians. (25S)-Δ(7)-Dafachronic acid (Δ(7)-DA, 1) is a member of the dafachronic acid hormonal series that regulates both development and lifespan of C. elegans. Despite its importance, effective tools for the illumination of its mode of action are lacking. Herein, we report an efficient synthesis of trideuterated Δ(7)-DA, [5,24,25-D3]-(25S)-Δ(7)-dafachronic acid ([D3]-Δ(7)-DA, 2), as a useful chemical tool for subsequent biological studies. Key steps for this bioinspired synthesis approach include site-selective aliphatic C-H oxidation mediated by methyl(trifluoromethyl)dioxirane (TFDO), and the iridium/phosphine-oxazoline-catalyzed late-stage asymmetric deuterium reduction.

A facile synthesis of deuterium labeled 2,2-dimethyl-[2H6]-succinic acid and its anhydride.

Deuterium labeled 2,2-dimethyl-[(2)H(6)]-succinic anhydride by a sequence of reactions involving Knoevenagel condensation of [(2)H(6)]-acetone with ethyl cyanoacetate in the presence of piperidine, Michael addition of cyanide, HCl hydrolysis, simultaneous decarboxylation, and subsequent dehydration using acetic anhydride in an overall yield of 34.23% based on [(2)H(6)]-acetone utilized in the reaction is reported. The title compounds were characterized and confirmed spectroscopically by Fourier transform infrared, (1) H-NMR, and Mass. The chemical purity as determined by HPLC was 99%. To the best of our knowledge, the synthesis of these specifically deuterium labeled compounds has not been reported so far.

Preparation of deuterium-labeled biotransformation products of 2,4,6-trinitrotoluene.

Methods for the preparation of deuterium-labeled analogs to six prominent biotransformation products of the explosive 2,4,6-trinitrotoluene were developed. These are useful as reference standards for stable isotope dilution techniques and for solid state (2)H NMR spectroscopic studies. Although syntheses for most of the target compounds in protiated form had been reported in the past, most of those were found to be poorly suited for the preparation of the deuterated materials. Selective reduction of [(2)H5]trinitrotoluene furnished [(2)H5]-4,6-dinitro-2-hydroxylaminotoluene, [(2)H5]-2,6-dinitro-4-hydroxylaminotoluene, [(2)H5]-2-amino-4,6-dinitrotoluene, and [(2)H5]-4-amino-2,6-dinitrotoluene. The syntheses of [(2)H10]-2,2'-azo-4,4',6,6'-tetranitrotoluene and [(2)H10]-4,4'-azo-2,2',6,6'-tetranitrotoluene were accomplished by selective oxidation of [(2)H5]-2-amino-4,6-dinitrotoluene and [(2)H5]-4-amino-2,6-dinitrotoluene, respectively.

Automated synthesis and purification of [18F]fluoro-[di-deutero]methyl tosylate.

Automated synthetic procedures of [(18)F]fluoro-[di-deutero]methyl tosylate on a GE TRACERlab FX F-N module and a non-commercial synthesis module have been developed. The syntheses included azeotropic drying of the [(18)F]fluoride, nucleophilic (18)F-fluorination of bis(tosyloxy)-[di-deutero]methane, HPLC purification and subsequent formulation of the synthesized [(18)F]fluoro-[di-deutero]methyl tosylate (d2-[(18)F]FMT) in organic solvents. Automation shortened the total synthesis time to 50 min, resulting in an average radiochemical yield of about 50% and high radiochemical purity (>98%). The possible application of this procedure to commercially available synthesis modules might be of significance for the production of deuterated (18)F-fluoromethylated imaging probes in the future.

Syntheses of deuterium labeled prenyldiphosphate and prenylcysteine analogues for in vivo mass spectrometric quantification.

A Wittig reaction employing Li(CD3)2CP(C6H5)3 was used to prepare d6-farnesol and d6-geranylgeraniol. Reductive amination of aniline-2,3,4,5,6-d5 was used to prepare the unnatural isoprenoid analogues d5-anilinogeraniol and d5-anilinofarnesol. All of these deuterated isoprenols were elaborated into their diphosphate and cysteine thioether derivatives suitable for use as stable-isotope labeled standards for quantitative mass spectrometric analysis.

Sodium-proton exchanger isoform-1: synthesis of a potent inhibitor labeled with deuterium and carbon-14.

Sodium-proton exchangers, NHEs are plasma membrane proteins that are essential in the regulation of intracellular pH of the myocardium. There are nine known variously expressed isoforms of NHEs with NHE-1 being the predominant isoform in the heart. N-[4-(1-acetyl-piperidin-4-yl)-3-trifluoromethyl-benzoyl]-guanidine (1) is a potent NHE 1-inhibitor with good pharmacokinetics. It was prepared labeled with deuterium and carbon-14 to aid in drug metabolism, pharmacokinetics, and other studies. The combination of Comins' reaction and reduction under deuterium gas was used to access deuterium labeled (1) starting from deuterium labeled pyridine. Carbon-14 labeled zinc cyanide was used to prepare [(14)C]-(1) in three steps, with a specific activity of 55.6 mCi/mmol.

Synthesis of a potent cathepsin s inhibitor labeled with deuterium and carbon-14.

Morpholine-4-carboxylic acid {(S)-1-[4-cyano-1-(3-morpholin-4-yl-propyl)-piperidin-4-ylcarbamoyl]-4,4- dimethyl-hexyl}-amide, (1) is a potent reversible and selective cathepsin S inhibitor. Deuterium labeled (1) was prepared in four steps in 62% overall yield from [2H8]- morpholine and chiral acid (6). Carbon-14 labeled (1) was obtained in two steps using sodium [14C]-cyanide in a modified Strecker reaction followed by amide bond formation with acid (6) in 74% overall radiochemical yield. The phosphate salt of this compound was produced by treatment with phosphoric acid in methanol in 97% yield.

Solid phase synthesis of selectively deuterated arenes.

A novel access to deuterated and D(3)CO-substituted arenes has been developed using immobilized triazenes as precursors. The linker system and the deuterating cleavage methodology could be shown to be compatible with various functional groups and are therefore suitable for the synthesis of derivatives only hardly available via comparable protocols.

α-Tocopheryl phosphate: uptake, hydrolysis, and antioxidant action in cultured cells and mouse.

α-Tocopheryl phosphate (α-TP), a water-soluble analogue of α-tocopherol, is found in humans, animals, and plants. α-TP is resistant to both acid and alkaline hydrolysis and may exert its own function in this form in vivo. In this study, the uptake, hydrolysis, and antioxidant action of α-TP were measured using α-TP with a deuterated methyl group, CD(3), at position 5 of the chroman ring (α-TP(CD3)). The hydrolysis of α-TP(CD3) was followed by measuring α-tocopherol containing the CD(3) group, α-T(CD3), in comparison to unlabeled α-tocopherol, α-T(CH3). α-TP(CD3) was incubated with cultured cells, and the intracellular α-T(CD3) formed was measured with HPLC-ECD and GC-MS. α-TP(CD3) was also administered to mice for 4 weeks by mixing in the diet, and α-T(CD3) was measured in plasma, liver, brain, heart, and testis to compare with endogenous unlabeled α-T(CH3). It was found that α-TP(CD3) was taken in and hydrolyzed readily to α-T(CD3) in cultured cells and in mice. The hydrolysis of α-TP(CD3) in cell culture medium was not observed. α-TP protected primary cortical neuronal cells from glutamate-induced cytotoxicity, and α-TP given to mice reduced the levels of lipid peroxidation products in plasma and liver. These results suggest that α-TP is readily hydrolyzed in vivo to α-T, which acts as an antioxidant, and that α-TP may be used as a water-soluble α-T precursor in intravenous fluids, in eye drops, or as a dietary supplement.

Simple synthesis of deuterium and 13C labeled trifluoromethyl phenyldiazirine derivatives as stable isotope tags for mass spectrometry.

The synthesis of trifluoromethyl diazirine with a stable isotope tag is reported. We found that both Friedel-Crafts acylation and reduction of aryl carbonyl to methylene, using commercially available stable-isotope reagents, were utilized for the synthesis of diazirinyl fatty acid derivatives. The stable isotope labeled diazirine may be valuable for identifying binding sites by mass spectrometry.

Synthesis and crystal structure of lithium beryllium deuteride Li2BeD4.

Single-phase ternary deuteride Li(2)BeD(4) was synthesized by a high-pressure high-temperature technique from LiD and BeD(2). The crystal structure of Li(2)BeD(4) was solved from X-ray and neutron powder diffraction data. The compound crystallizes in the monoclinic space group P2(1)/c with lattice parameters a = 7.06228(9) A, b = 8.3378(1) A, c = 8.3465(1) A, beta =93.577(1) degrees, and Z = 8. Its structure contains isolated BeD(4) tetrahedra and Li atoms that are located in the structure interstices. Li(2)BeD(4) does not undergo any structural phase transitions at temperatures down to 8 K.

Preparation of deuterated methyl and dimethyl substituted nicotinoylating agents for derivatization of the N-terminal of protein.

Methyl groups of 6-methylnicotinic acid and 2,6-dimethylnicotinic acid were deuterated by an H-D exchange reaction under conditions of 1% NaOD/D(2)O on heating. With a condensation reaction between the D-labeled nicotinic acid derivative and N-hydroxysuccinimide with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, the nicotinoylating agents, 1-(6-methyl[D(3)]nicotinoyloxy)succinimide (2c) and 1-(2,6-dimethyl[D(6)]nicotinoyloxy)succinimide (2f) were prepared. Both D-labeled nicotinoylating agents and their unlabeled counterparts quantitatively modified the N-terminal of protein.

Total synthesis of 2',3',4',5',5' '-(2)h(5)-ribonucleosides: the key building blocks for NMR structure elucidation of large RNA.

The diastereospecific chemical syntheses of uridine-2',3',4',5',5' '-(2)H(5) (21a), adenosine-2',3',4',5',5' '-(2)H(5) (21b), cytidine-2',3',4',5',5' '-(2)H(5)(2)H(5) (21c), and guanosine-2',3',4',5',5' '-(2)H(5) (21d) (>97 atom % (2)H at C2', C3', C4', and C5'/C5' ') have been achieved for their use in the solution NMR structure determination of oligo-RNA by the Uppsala "NMR-window" concept (refs 4a-c, 5a, 6), in which a small (1)H segment is NMR-visible, while the rest is made NMR-invisible by incorporation of the deuterated blocks 21a-d. The deuterated ribonucleosides 21a-d have been prepared by the condensation of appropriately protected aglycone with 1-O-acetyl-2,3,5-tri-O-(4-toluoyl)-alpha/beta-D-ribofuranose-2,3,4,5,5'-(2)H(5) (19), which has been obtained via diastereospecific deuterium incorporation at the C2 center of appropriate D-ribose-(2)H(4) derivatives either through an oxidation-reduction-inversion sequence or a one-step deuterium-proton exchange in high overall yield (44% and 24%, respectively).