Acetic deuteriated

Most of the available KSIEs measured in methanol, ethanol or acetic acid and their deuteriated analogues are shown in Tables 20 and 21. They must be compared with the 0Br factor [1.35 and 1.27 in methanol and ethanol,... 

Treatment of trans,trans-2,6-ociddiene (122) with deuteriated formic acid HCO2D in the presence of deuteriosulphuric acid gave the cyclized formate ester 123. A concerted mechanism (equation 63) was proposed for this reaction73. The stereospecific ring-closure of the 1,4-cyclohexadiene derivative 124 in acetic anhydride/perchloric acid affords the octalin 125, which was isolated as the diacetate 126 (equation 64)74. 

In the case of the synthesis of 10,19,19,19-2H4-vitamin A, the most useful for biological studies, three deuterium atoms were incorporated into /i-ionone 30, in >98% by deuterium exchange with excess D2O in the presence of Na02H (and pyridine). The tri-deuteriated 30, utilized in Wittig-Horner reaction with dideuterio triethyl phosphonate, provided tetradeuteriated ethyl /J-ionilidene acetate 31 with more than 98% 2H4 (by NMR). No deuterium loss in the subsequent synthetic steps was observed as evidenced by MS and NMR analysis. 

Thiophenyl acetates (366 R = Me) and propionates (366 R = Et) react with electrogenerated polysulflde ions S3 in DMF to yield thiocarboxylate ions, thiolate ions, and phenyl tetrasulfanide (367), the last deriving from the reaction of thiolate ions with sulfur (Scheme 48). Smdies of the aminolysis by a set of substimted anilines of Y-aryl dithio-2-thiophenates (368 X = S) and dithio-2-furoates (368 X = O) in acetonitrile have shown that the rate-determining step in these reactions is the departure of the thiophenolate ion from the zwitterionic tetrahedral intermediate T= = (Scheme 49). Experiments with deuteriated anilines yielded k i/IcQ values of 1.7-1.9,... 

Thus, dissolving acetic acid in deuteriated water will rapidly give deuteriated acetic acid by acid-base equilibria. However, if the deuteriated acetic acid were then dissolved in normal water, the reverse process would wash out the label equally rapidly. 

Methyl 8-oxooctanoate-4,5-D2, 35, and methyl 12-oxododecarbate-4,5,8,9-D4, 36, have been synthesized32 as shown in equations 13 and 14 by monoozonization and sodium acetate cleavage of 1,5-cyclooctadiene and 1,5,9-cyclododecatriene, respectively. The resultant unsaturated aldehydic acids 37 and 38 have been converted to the corresponding acetal esters, which have been deuteriated with Wilkinson s catalyst33 and hydrolysed to the deuterium-labelled aldehydic esters 35 and 36 in 47% and 49% overall yields and... 

The 2- 3-position reactivity ratio for furan for deuteriation in acetic acid/trifluoroacetic acid (2 1) was determined as 500 (72MI1), but decomposition severely affects the accuracy of the (3-exchange rate, and hence of the reactivity ratio. 

Bean and Wilkinson have reported deuteriation rates for several alkyl-pyrroles in buffered aqueous dioxan-acetic acid at 25°C [78JCS(P2)72] under these conditions, neither 2-formyl- nor 2-nitropyrrole underwent exchange. Partial rate factors are given in Table 6.2. These show a number of interesting features. 

Rates of dedeuteriation and detritiation of 5-substituted, 3-labeled (deuteriated and/or tritiated) indoles have been determined in both aqueous mineral acid and in acetic acid [72JCS(P2) 1618]. Substituent effects in both series were similar [slightly larger for dedeuteriation, which is a... 

Garbisch (1965) explained predominant bromination (67%) on the methylene site of 2-methylcyclohexanone 1681 (6-position) in methanol (as opposed to 4% in ether) as due to easier formation of the more stable /F,6-enol ether from the acetal. Similar peculiar regioselectivities for acid-catalysed bromination, chlorination and deuteriation of [691-1731 have been reported... 

Acyclic and cyclic ketals derived from aromatic aldehydes have been deprotonated with n-BuLi (4 h) at —45 °C or LDA (24 h) at —45 °C to room temperature, and the corresponding organolithiums 445 and 446 deuteriated with MeOD655,656. 2-Aryl acetal anions show a great tendency to rearrange and/or fragment657 when they bear the electron-withdrawing oxazoline moiety at the para-position. 

Yur ev et al. 2 prepared deuteriated selenophenes from the respective halogenated compounds by halogen-deuterium replacement. Thus, 2-deuterio-, 2,5-dideuterio-, tetradeuterioselenophene, 3-methyl-, and 5-methyl-2-deuterioselenophene were obtained from the corresponding iodoselenophenes on reduction by zinc in deuteriated acetic acid. 3-Deuterioselenophene was obtained from 3-selenienyl-lithium hydrolyzed with deuteriated acetic acid at — 7 0°C the lithium derivative was obtained from 3-bromoselenophene and ethyllithium, also at — 70°C. The deuterium content was determined by combustion, the water being analyzed by the drop method.43... 

A particularly illuminating study involving isotopic substitution concerns the reaction of N-tritiated diethylamine with methyl benzoate (Kitamura et al., 1977). It was found that tritium was preferentially substituted into the p-position. There was also substantial substitution in the o-position but more surprising, the methyl group of the ester was labelled. It was proposed that reaction occurs as shown in Scheme 7 via radical ions [68] and [69]. 4-Cyano-benzyl-acetate, on irradiation in the presence of triethylamine is cleaved to give 4-cyanotoluene and 4,4 -dicyanobibenzyl (Ohashi et al., 1977d). When O-deuteriated methanol was used as solvent, deuterium was incorporated... 

With acetic anhydride, the nitrone (23) was unchanged, but with toluene-p-sulphonyl chloride in heterogeneous alkaline medium (23) gave the oxaziridine (30), whereas in a neutral solvent it led to (31) (Scheme 4). Conditions for deuteriation of the nitrone (23) were established in heterogeneous neutral medium, no deuteriation occurred in homogeneous alkaline medium, quantitative deuteriation at C-21 was effected in heterogeneous alkaline medium, deuteriation was incomplete, but in heterogeneous acidic medium, rapid incorporation was observed. ... 

Pincock and his co-workers have studied the photochemical fragmentation reactions of the esters (31). This system has an in-built electron accepting sensitiser. When (31a-c) are irradiated in methanol the principal reaction is fission to yield the styrene (32) and p-cyanobenzoic acid. The other products formed from the reactions are the styrene addition products (33)-(35). The authors propose that the Norrish T) e II process in this instance involves a proton transfer and this occurs within the zwitterionic biradical formed as the primary intermediate on electron transfer. Further proof of the authenticity of this mechanism was obtained by irradiation of the deuteriated derivatives (31 d, e). The results of a study of the photochemical decomposition of benzyl phenylacetate, as a suspension in water over Ti02, have been reported. Bond fission is the result of irradiation of (36) in cyclohexane/ethyl acetate. A Norrish Type II hydrogen abstraction occurs with the elimination of the enone moiety. This affords a path to the CD ring system (37) of vitamin D. 

In 1,2-iraws-disubstituted compounds Reeves and Stromme (1961a) have shown from low-temperature intensity measurements of the separated adjacent proton resonances that conformational preferences ee or aa are a function of the polarity of the solvent. Deuteriation of both sets of adjacent CH2 protons at the 2- and 6-positions simplifies the appearance of the —CHX proton in cyclohexyl compounds. First-order deuterium couplings contribute to a considerable apparent line width of 3-6 c.p.s. (Allan et al., 1963 Premuzic and Reeves, 1962). At low temperature the position of the adjacent proton resonance is a reliable measurement and it has been shown, using the time-weighted average method, that the acetate, formate, trifluoroacetate and nitrate esters have the following equatorial preferences 76%, 61%, 76% and 73% with probable errors of + 1 %. 

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