Labelling alkyl chloride

This experiment also suggests a convenient method to produce deuterium-labelled alkyl chloride from the corresponding aldehyde/ketone. 

Rapid synthesis of39CI-labelled alkyl chlorides... 

Preparation of the C-labelled compound 65 was accomplished in a manner analogous to Scheme 14. Friedel-Crafts acylation of 44 was conducted with [2- C]-chloroacetyl chloride under aluminum trichloride catalysis to give the radiolabelled intermediate 64 (48 mCi/mmol). The carbonyl group of 64 was reduced with triethylsilane and the resulting alkyl chloride was reacted with piperazine 40 to provide C-labelled ziprasidone (65). The HCI salt of 65 was formed resulting m a final compound with a specific activity of 9.6 mCi/mmol. 

F-labelled alkylating agents, such 4-[18F]fhiorophenethyl bromide, 166, and 4-[18F]flu-orophenbutyl chloride, 167, have been synthesized202 according to a new procedure (equation 100) which is not limited to activated nitroarenes. It involves [18F] displacement of... 

Diazepine 243 (R = H) gave a monoacetyl and a nitroso derivative.286 Alkylation of 243 (R = H) with sodamide and dialkylamino-alkyl chlorides in dioxane substitutes only at the 10-position to give 245 289,291 while alkylation of 243 [R= (CH2)2N(C2H6)2] gave 246. This same type reaction has been used to introduce a labeled side chain into 246.292d... 

To draw the elimination products, locate the p carbons and look for H atoms that are trans to the leaving group. The given alkyl chloride has two different p carbons, labeled Pi and P2. Elimination can occur only when the leaving group (Cl) and a H atom on the p carbon are trans. 

Vacuum-transferrable volatile materials (b.p. up to about 180-200 C) often encountered include (aside from those prepared as intermediates in the radiochemical laboratory) commercial building blocks such as [ C] methyl iodide and other low-molecular-weight carbon-14-labeled alkyl halides, methanol, ethanol, benzene, acetic and haloacetic acids, acetyl and haloacetyl chlorides and dimethylformamide. These compounds are most appropriately handled on vacuum manifolds in the same way as gases, but some may, with proper experimental design, be used without such systems. In the latter case, it is strongly recommended that safety measures be taken against the possibility of the release of volatile radioactivity. 

The first A/ -oxides of the 1,2,4-thiadiazole ring system have been reported and were prepared by condensation of benzamidoximes (86) with 4,5-dichloro-l,2,3-dithiazohum chloride (87). A -labelling showed the compounds to be 4-oxides (88) and a mechanism was proposed for their formation. Alkyl amidoximes and arylamidoximes with electron-withdrawing substituents did not give A/ -oxides, but only the dithiazolone (89) and the dithiazolthione (90) <96CC1273>. 

Alkylation by allylic halides is usually a satisfactory reaction, and in this case the reaction may proceed through a cyclic mechanism.81 For example, when l-14C-allyl chloride reacts with phenyllithium, about three-fourths of the product has the labeled carbon at the terminal methylene group. 

Ealy [ 75 ] also used conversion to alkyl mercury iodides for the gas chromatographic determination of organomercury compounds in benzene extracts of water. The iodides were then determined by gas chromatograph of the benzene extract on a glass column packed with 5% of cyclohexane-succinate on Anakron ABS (70-80 mesh) and operated at 200 °C with nitrogen (56 ml min-1) as carrier gas and electron capture detection. Good separation of chromatographic peaks was obtained for the mercury compounds as either chlorides, bromides, or iodides. The extraction recoveries were monitored by the use of alkylmer-cury compounds labelled with 203 Hg. 

The title compound, l-[bis-(4-fluorophenyl)methyl]-4-(3-phenylpropenyl) piperazine, 123, clinically used as a calcium channel blocker of the piperazine class166, has been labelled with 18F by alkylation of Af-cinnamylpiperazine with 4-[18F]fluoro-4 -fluoroben-zhydryl chloride 124 (equation 73)167. The biodistribution of 123, its effect on the dopamine reuptake blockers and metabolic products are under investigation167. 

H2-labelled thioridazine 56 (the phenothiazine-type antipsychotic agent) has been obtained recently39 for metabolic and pharmacokinetic studies by a new route (equation 16) from 2-(2-hydroxyethyl)piperidine 57. The key steps in this sequence of reactions involve ruthenium tetroxide oxidation of the 7V,0-diacetylated starting material 58 and subsequent lithium aluminium deuteride reduction of the 2-(2-acetoxyethyl)-6-piper-idinone (59, R = Ac). Treatment of 60 with thionyl chloride produced 2-(2-chloroethyl)-l-methyl[6,6-2H2]piperidine which, on N(10)-alkylation of 2-methylthio-10i/-phenothia-zine, yielded 56. For each of the seven steps in the conversion of 57 to 56 the yield has been at least 76%40. 

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