5-deutero, preparation

Deuterated Model Compounds and Protodedeuteration Rate Measurements. Protodedeuteration rate studies were outlined for 2,4,6-trideuterophenol and 2,4,6-anisole, 3,5-dideutero- and 4,6-dideutero-guaiacols, 3,5-dideuteroveratrole, 5-deutero-4-hydroxy-3-methoxytoluene, and 2,6-dideutero-4-hydroxy-3-methoxytoluene (6). Using appropriate combinations of acid- and base-catalyzed deuterium exchange reactions, the following deuteroderivatives were prepared in this study 3,5-dideutero-and 4-deutero-2,6-dimethoxyphenols, 4,6-dideutero- and 5-deutero-1,2,3-trimethoxybenzenes, and 2,6-dideutero-4-hydroxy-3,5-dimethoxytoluene. 

The 5-deutero and 4,6-dideutero derivatives of 1,2,3-trimethoxy-benzene were prepared by methylating the corresponding deuterated 2,6-dimethoxyphenols with dimethyl sulfate in 10% NaOH at room temperature. 

The deutero-5,6-0-benzylidene ascorbic acid may be prepared next way ... 

Deuterated-3,9-dialkyladenines have been similarly prepared from appropriate aminoimidazole carboxamidines by deuteroformylation with DC02D and cyclization of the resulting deutero-formamidoimidazoles with base <90CPB99>. Comparison of the H NMR spectra of the deuterated and nondeuterated derivatives has permitted a distinction to be made between C-2 and C-8 proton signals in a series of 3,9-dialkylated adenine salts. 

Deuterothiirane and 2,2-dideuterothiirane were prepared by reaction of 1-deutero- or 1,1-dideuteroethylene carbonate with potassium thiocyanate. The thiiranes were oxidized to corresponding 2-deutero- and 2,2-dideuterothiirane 1-oxides in reaction with MCPBA (Scheme 103) <1998CEJ441>. 

It should be noted here that there is a very wide latitude in the quality of the commercially available materials. Recently reported experiences with ferric hematoporphyrin derivatives are quite typical. In general, esters are better than the unesterified bases. For the blood-derived materials the usual order of quality goes deutero, hemato, and meso, with protoporphyrin the worst. For a well-defined preparation of natural porphyrins, it is always best to purify the starting material and to characterize it ° satisfactorily before carrying out any chemical modifications. 

The nuclear magnetic resonance (NMR) spectrum (Fig. 2) was obtained by preparing a saturated solution of meperidine hydrochloride, U.S.P. (Wyeth Lot No. F-665901) in deutero chloroform containing tetramethylsilane as internal reference. The only exchangeable proton is the hydrogen associated with HC1. The NMR proton spectral assignments are given in Table II. 

A. (1992) The preparation of [2-deutero-3-fluoro-D-ala ]cyclosporin A by directed biosynthesis. J. Antibiot. 45, 133-135. 

Nonaqueous solutions of deuterazoic acid have also been reported in the literature. For example to prepare a solution in chloroform, 2 g sodium azide was dissolved in deuterium oxide. To this was added a solution of 1.2 g deutero-phosphoric acid (85% w/w in deuterium oxide), and the mixture was extracted five times with 20 ml chloroform [60]. A different approach was used to make a carbon tetrachloride solution of deuterazoic acid [57] A solution of hydrazoic acid in carbon tetrachloride as prepared above was shaken with deuterium oxide, resulting in a 75-80% conversion to deuterazoic acid. 

A number of unexplained factors warrant mention. Orientation of elimination differs for secondary and tertiary structures. The peculiar predominance of cis- rather than /ra/ii-olefin may arise from the relative stabilities of the proton-olefin complexes. but a more certain conclusion would be possible if the stereochemistry of the dehydration in the acyclic series had been determined. Assumption of the anti stereospecificity known to be favoured by the cyclohexyl systems may be unsound especially in the light of the recent stereochemical findings in base-catalysed elimination reactions (Section 2..1.1(e)). The solution of the problem of the cis/trans ratios may lie in the duality of mechanism, namely the syn-clinallanti complexity. Certainly recent results on the dehydration of threo- and eo t/iro-2-methyl-4-deutero-3-pentanols on thoria show syn-clinal rather than anti stereospecificity as indicated by deuterium analysis of the cis- and /rn/iJ-4-methyl-2-pentenes, but in these cases the trans isomer was formed in a three-fold excess over the m-olefin . Of course, the dehydration reactions on the less acidic thoria may not be good models for alumina but a knowledge of stereochemistry in the acyclic series might prove an invaluable aid in the elucidation of the mechanism. There is obviously plenty of scope for future kinetic investigations which at the moment sadly lag behind preparative studies. 

The PMR spectra were taken at 80 MHz with a Varian FT-80A NMR spectrometer. Samples (0.5 mL) were prepared in deutero-chloroform at concentrations of 10-25% by weight. Tetramethyl-silane (TMS) was used as an internal reference. Chemical shifts... 

The A-300/DNA nanocomposite was used to prepare two samples under the same conditions. The first sample was with 5 wt% of distilled water, and the second sample was with 5 wt% of an aqueous solution of 0.1 mg/mL (0.01 wt%) Cgo- A mixture of 2 1 deuterochloroform and deutero-acetonitrile was used as a solvent. 

Examples of gas chromatographic isotope separation are shown in O Figs. 51.10 and O 51.11. The gas chromatographic trace of a separation of a mixture of protio and deutero-acetylenes is shown in Fig. 51.10 (Phillips and Van Hook 1967). The separation is interesting, all known preparations of these acetylenes lead to a disproportionated mixture of C2H2, C2HD,... 

The use of deuterium oxide and sodium deuterium oxide in the preparation of Raney nickel leads to the formation of deutero Raney nickel suitable for replacing dithioacetals with deuterium The method suffers from some scrambling of the isotope often leading to products of low isotopic purity. Deuteration of (25R)-5a-spirostan-12-one (II) by this... 

Bilayer structures were prepared on cleaned silicon wafers (approximately 3 mm thick and 75 mm diameter) as follows 5 min exposure to oxygen plasma, followed by removal of native oxide layer by immersion into a solution of (10 2)% volume fraction HF and (5 2)% volume fraction NH3F in ultra pure water for (15 5) s. An oxide layer was regrown in a UV/Ozone chamber for (120 1) s followed by priming with hexamethyldisilazane vapor (HMDS). The lower layer consisting of the deutero-poly(butoxycarboxy styrene) (d PBOCSt) (Mr,n = 21000, = 2.1) was spin-coated from a propylene... 

Isotopic atoms have been introduced into amino acids or molecules employed in the synthesis of amino acids, by (a) catal]rtic addition of D to carbon-carbon double bonds (161, 459, 758, 852), (b) methylation with trideuteromethyliodide (831, 833), (c) syntheses of deuteromalonio ester derivatives from u-phenyl deuteroalkyl bromides and malonic ester (626), (d) preparation of deutero amino acids by reaction of amino acids with deuterosulfuric acid (576, 667, 692, 758, 805, 852), (e) catalytic reduction with DgO and amination of a-keto acids (668), (f) preparation of deuteroaliphatic acids by reaction of aliphatic acids with DjO (690), (g) catalytic reduction and amination with of a-keto acids (690,... 

Deutero-nltrlc acid is prepared by entraining gaseous NO2 in air or oxygen in D2O in a packed tower (Item 10). Potassium deuteroxide is prepared by electro-dialysis of potassliim carbonate in a two-compartment cell separated by a cation exchange membrane, the potassium ion passing into the anode compartment to form KOD, without contamination by the carbonate ion (Item 10). 

If mechanism 1 was operating, then the deuterium should be maintained in the product. However, if mechanism 2 was operating, you would expect to not see any deuterium in the product. The deuterated tosyl amide 32 was easily prepared from commercially available deutero benzaldehyde and employed in the reaction. The product a-ketoamide 33 was isolated and characterized. The product was found to have >95% incorporation of the deuterium at the alpha position of the ketoamide. This rules out the possibility of the second mechanism and provides evidence that the product keto-amide 33 is not undergoing epimerization under the reaction conditions. Thus it should be possible to carry out an enantioselective version of this reactions utilizing the appropriate chiral thiazoliiun salt. 

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