Modification ethylamine

The appearance of the 2-(indol-3yl)ethylamine (tryptamine) unit in both tryptophan-derived natural products and in synthetic materials having potential pharmacological activity has generated a great deal of interest in the synthesis of such compounds. Several procedures which involve either direct 3-alkylation or tandem 3-functionalization/modification have been developed. Similarly, methodology applicable to preparation of tryptophan analogues has been widely explored. 

The method described is rather general. With appropriate modifications for the purification of the aim ne the method yields a- -tolylethylamine (72 per cent), a-p-chlorophenylethyl-amine (65 per cent), a -/)-bromophenylethylamine (63 per cent), a- -xenylethylamine (66 per cent), and a-(/9-naphthyl)-ethylamine (84 per cent) from the corresponding ketones. 

Secondly, they are prepared here by completely different processes, each of which is amenable to modification to other, potentially useful mono-substituted tryptamines (NRT S, where the R is a sizable alkyl group). There is the oxalylamine route (used here with ethylamine for NET) and the alkyl halide route (used here with isopropyliodide for NIPT but which proved to be rather useless in making NET where the major product was the quaternary salt). With these two procedures available, there is almost no limit to the potential identity of that mono-group on the nitrogen atom of tryptamine. Quite a few have already been made. Let me list some examples. 

But what can be said about the ethylamine end of the phenethylamine molecule This is the veritable backbone that holds everything together, and simple changes here can produce new prototypes that can serve as starting points for the substituent game on the benzenering. Thus, just as there is a family of compounds based on the foundation of phenethylamine itself, there is an equally varied and rich families of other compounds that might be based on some phenethylamine with a small modification to its backbone. 

Sakai, K., Yoshida, S., Hashimoto, Y., Kinbara, K., Saigo, K. and Nohira, H. (1998) Reciprocal resolution of l-(4-methylphenyl)ethylamine and 2-hydroxy-4-phenylbutyric acid, and habit modification of a less-soluble diastereomeric salt with a chiral additive, Enantiomer 3, 23-35. 

This method [Eq. (10)] was first used in 1930 by Kondo and Tanaka60 for the preparation of 4-hydroxy-5-methoxytetrahydroisoquinoline from j8-hydroxy-j8-(o-methoxyphenyl)ethylamine and methylal (mixed in aqueous HC1). Such ethanolamine derivatives are frequently used in the Bischler-Napieralski synthesis of isoquinolines61 as the Pictet-Gams modification. In this case, the reaction proceeds with dehydration to yield completely aromatic isoquinolines directly. Preparations of the ethanolamines have been reviewed.62... 

White phosphorus in contact with ethylamine in a sealed tube at room temperature tons first red, then dark-red, and finally rives a black precipitate of approximate composition Pc.3 jH (C2HsNH2)o.26 - Other amines give apparently similar products Obviously the effect of amine consists mainly in the conversion of white phosphorus to another modification... 

Potent agonists for the Hg receptor are obtained by simple modifications of the histamine molecule. The imidazole ring is very important for Hg agonistic activity [17]. Methylation of one of the nitrogens or replacements with other aromatic ring systems are not tolerated [22]. In contrast, subtle changes of the ethylamine side chain have proven to be very usefiil [17]. 

Raney nickel catalyst was modified with 0.5 wt % V or Mg to increase the selectivity to secondary amines in the alkylation of ammonia with n-propanol or i-butanol. Due to the modification selectivities around 70-80 % were obtained at 90-95 % conversions. The mixed secondary alkylamine, N-ethyl-N-n-butylamine was prepared from ethylamine and n-butanol on a commercial Cu0-Zn0-Al203 catalyst. The highest yield of EtNHn-Bu around 76 % was obtained at 190 °C and EtNH2/n-BuOH molar ratio 5 or above. 

The hydrogenation steps are the rate limiting steps over the fresh catalyst. After an experiment lasting two hours, we observed a dramatic decrease of the activity, specially of the MEA conversion and the disappearance of the intermediates. Furthermore, the main products, DEMA and DEA, were formed. These results show that the adsorption properties of the catalysts vary very much during the reaction since ethylamine was mainly adsorbed and led to DEA. We suppose that these significant modifications could be due to the polymerisation of reaction intermediates such as imine or enamine. The polymers could remain on the catalyst surface and modify the nature and the number of active sites. In previous works, we remarked that these secondary reactions could modify the catalyst surface (16,17). 

From this study the following reaction scheme describing the transformation of ethylamine to the main product DMEA and by-products was established. From a kinetic point of view, steps 2 and 3 are the rate determining reactions. It follows that the DMEA selectivity is increased by modifying the acido-basicity of copper chromite used as a catalyst. In fact, the change of the catalyst basicity can decrease the MEA condensation to form DEA without modification of the hydro-dehydrogenating properties of the catalyst which are necessary for the methylation of ethylamine with methanol (steps 1 and 3). 

New modifications of the traditional approach to isoquinoline synthesis via carbocation intermediates continue to be reported. Abnormal products of the Bischler-Napieralski reaction were observed <97JCS(P1)2217>. A stereoselective introduction of a quaternary carbon center in the A-acyliminium cyclization (Scheme 14) of the chiral enamide 46 affords an asymmetric synthesis of tetrahydroisoquinolines <97T2449,3045>. An asymmetric Pictet-Spengler reaction has been developed mediated by the chiral urethane 47 <97T16327>. A Pummerer reaction of A-acyl-A-(aryl)methyl-2-(phenylsulfinyl)ethylamine allows cyclization to the 4-phenylthio-... 

The utilization of MPPs and related compounds as active materials to detect tri-ethylamine, based on the changes on mass and conductivity, was reported by Di Natale [54], The selectivity depends mostly on the central metallic ion, which shows the possibility of changing the sensor selectivity with minor modification of the synthesis process. Conductivity measurements confirmed that the charge transport happens inside the MPPs, indicating the occurrence of a different conduction mechanism among these macrocycle compounds. 

The effect of modifier structure was studied in the hydrogenation of EtPy in MeOH and in (DMF + water) Heinz et al. showed that a Pt-alumina catalyst modified with (5)-(-)-l-(l-naphthyl)ethylamine gave an ee of 82% in the hydrogenation of EtPy, whereas modification with Cnd under the same conditions gave only ee s of 73-75% but in the hydrogenation of the C=C bond in cinnamic acids ee values reached only 4-12%... 

Alkylsilanes react with acid chlorides under catalysis with AICI3 to give unsym-metrical ketones.Compound (45) is obtained by reaction of 5-tri-methylsilylcyclopentadiene with dichloroacetyl chloride in the presence of tri-ethylamine, and it may be converted into prostaglandins or into loganin aglycone acetate (46), by subsequent modifications. Compounds (47) and (48) are obtained from photochemical cycloadditions of alkynylsilanes, RC=CSiMe3, with cyclopent-2-enone. ... 

---