Amines pseudoephedrine

Compounds used are sympathomimetic amines pseudoephedrine, phenylephrine and ephedrine ... 

A number of other types of chiral auxiliaries have been employed in enolate alkylation. Excellent results are obtained using amides of pseudoephedrine. Alkylation occurs anti to the a-oxybenzyl group.93 The reactions involve the Z-enolate and there is likely bridging between the two lithium cations, perhaps by di-(isopropyl)amine.94... 

Paper chromatography has been used to separate and detect pseudoephedrine hydrochloride from other pharmacologically active amines. Whatman No. 1 paper developed in n-butanol water 95% acetic acid (4 5 1), n-butanol toluene water 95% acetic acid (10 10 5 5), ethyl acetate water 95% acetic acid (3 3 1), or chloroform water 95% acetic acid (10 5 4) gave Rf values of 0.73, 0.35, 0.57, and 0.52 for pseudoephedrine hydrochloride respectively. Visualization of pseudoephedrine hydrochloride was done by spraying the chromatogram with 0.5% bromcresol green in methanol or 0.2% nin-hydrin in acetic acid butanol 5 95.30... 

Pseudoephedrine hydrochloride has been separated from other amines by gas chromatography. The oxazolidine... 

This operation is necessary to hydrolyze the pseudoephedrine aminal which forms as a direct product of the reduction, in addition to the desired aldehyde. The use of the additional 700 mL of 1 N aqueous hydrochloric acid solution was found to be crucial for this hydrolysis reaction. 

The pH of the aqueous phase following the addition of sodium bicarbonate is approximately 4. If the pH is less than 4, additional sodium bicarbonate should be added until the pH is 4 or slightly above. Small amounts of the pseudoephedrine aminal remain at this point, but are hydrolyzed during the rotary evaporation step. 

In addition to quenching excess hydride, the acidification and subsequent extraction steps remove pseudoephedrine and any tertiary amine reaction by-product the latter is otherwise difficult to remove by column chromatography. 

Diastereomeric complexes can also be formed by ion-pairing of an enantiomer with a chiral counterion. In order to form this diastereomeric complex, it has been postulated that at least three interaction points between the ion pair are required [250]. Nearly all of these form weak complexes in aqueous mobile phases. Consequently, the chromatographic methods that have been developed have been either silica or diol columns with low-polarity mobile phases. Enantiomeric amines, such as the beta-blockers, have been optically resolved when (-l-)-lO-camphorsulfonic acid was used as the chiral counterion [251]. Enantiomers of norephedrine, ephedrine, pseudoephedrine, and phenyramidol have all been resolved from their respective enantiomers with n-dibutyltartrate [252]. Enantiomers of naproxen, a chiral carboxylic acid, are resolved from each other by either using quinidine or quinine in the mobile phase [253]. In these studies, silica... 

In this enantiodifferentiating photoreduction, the chiral amine plays two roles, as a chiral inductor and as an electron donor. Irradiation of 25 (Scheme 10) in a hexane slurry of unmodified NaY zeolite gave only the intramolecular hydrogen abstraction product 26. However, photolysis of 25 coimmobilized with ephedrine, pseudoephedrine, or norephedrine in NaY supercages afforded the reduction product 27 along with 26. It is clear that the immobilized amine plays the decisive role in the photoinduced electron-transfer reduction of 25, since 27 was not formed in unmodified or (— )-diethyl tartrate-modified zeolites. Consequently, the ee of obtained 27 was independent of the loading level of the chiral inductor. 

The strategy presented above with phenyl cyclohexyl ketone has been established to be general by investigating a number of aryl alkyl ketones and diaryl ketones [281,283]. The best cases of % ee are summarized in Schemes 14 and 15. 2-Ethoxybenzophenone 32 gives intramolecular cyclization product 33 as the only product in solution as well as within NaY. However, in NaY in the presence of chiral amines, intermolecular reduction product 34, in addition to 33, was obtained (Scheme 16). More importantly, with pseudoephedrine and (l/ ,2/ )-... 

Most sympathomimetic amines, such as amphetamine, are available only by prescription others such as phenylephrine and pseudoephedrine, which also are reported to interact similarly with MAO inhibitors, are found in most popular non-prescription cold and allergy preparations. It is important that patients being treated with MAO inhibitors avoid using products containing these agents. 

Fig. 26 Reversed-phase liquid chromatographic separation of GITC-derivatized amines. 1 = R,R-pseudoephedrine, 2 = 5,5-pseudoephedrine, 3-R,5-ephedrine, 4 = 5, R-ephed-rine, 5 = 5-methamphetamine, 6 = R-methamphetamine. (From Ref...

Pseudoephedrine is an orally active sympathomimetic amine exerting its decongestant action by acting directly on a-adrenergic receptors in the respiratory tract mucosa producing vasoconstriction resulting in shrinkage of swollen nasal mucous membranes, reduction of tissue hyperemia, edema, and nasal... 

Amphetamine and methamphetamine (Figure 34-19) are CNS stimulant drugs that have limited legitimate pharmacological use. ° They are used to treat narcolepsy, obesity, and attention-deficit hyperactivity disorders. However, they produce an initial euphoria and have a high abuse potential. Other sympathomimetic amines that also have high potential for abuse include the designer amphetamines, ephedrine, pseudoephedrine, phenylpropanolamine, and methylphenidate (Ritalin). 

Figure 34-19 Chemical structure of sympathomimetic amines. Ephedrine and pseudoephedrine are diastereoisomers.

---