2- ethylamine functional

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. 

Rapid aminations of 1-bromonaphthalenes with piperidine under microwave irradiation were reported by Hamann using Pd2(dba)3/rac. PPFA (N,N-dimethyl-1-[2-(diphenylphosphanyl)ferrocenyl]ethylamine) precatalyst in combination with NaO-t-Bu in toluene at 120 °C (Scheme 92) [97]. Typically, reactions performed under conventional heating at 120 °C (oil bath) were still progressing after 16 h and were essentially complete by 24 h, whereas the microwave reactions appeared to be finished after 10 min. The same reaction conditions were also useful to functionalize 5- and 8-bromoquinolines with anilines and aliphatic amines (Schemes 93 and 94). Remarkably, no product formation was observed with 5-bromo-8-cyanoquinoline and 5-bromo-8-methoxyquinoline under conventional heating for 24 h at the same temperature, while the desired 5-aminoquinolines were smoothly obtained under microwave irradiation in a reaction time of only 10 min. 

The spiro compound 206 was prepared in five steps from (S)-l-naphthyl-ethylamine and was composed of a mixture of imine and enamine tautomers. Reduction of the imine function by sodium borohydride occurred on the less hindered si face, leading to the diamine with the R configuration of the newly formed stereo center, then the N-benzyl substituent was removed by hydrogenolysis to give 207 with good overall yield [98] (Scheme 30). 

The molecular modelling approach, taking into account the pyruvate—cinchona alkaloid interaction and the steric constraints imposed by the adsorption on the platinum surface, leads to a reasonable explanation for the enantio-differentiation of this system. Although the prediction of the complex formed between the methyl pyruvate and the cinchona modifiers have been made for an ideal case (solvent effects and a quantum description of the interaction with the platinum surface atoms were not considered), this approach proved to be very helpful in the search of new modifiers. The search strategy, which included a systematic reduction of the cinchona alkaloid structure to the essential functional parts and validation of the steric constraints imposed to the interaction complex between modifier and methyl pyruvate by means of molecular modelling, indicated that simple chiral aminoalcohols should be promising substitutes for cinchona alkaloid modifiers. Using the Sharpless symmetric dihydroxylation as a key step, a series of enantiomerically pure 2-hydroxy-2-aryl-ethylamines... 

It was only around 1850 that the first amines were discovered by Wurtz [2], who considered them as alkylated (or arylated) derivatives of NH3. Nowadays, it is well known that the amine function is widespread among biologically important compounds, but mostly it is present in polyfunctional molecules such as amino acids, alkaloids, etc. Simple amines are very rare in nature, with the exception of tri-ethylamine and the trimethylammonium ion which come from the putrefaction of proteins. 

Polymers containing pendant carbamate functional groups can be prepared by the reaction of phenyl isocyanate with poly(vinyl alcohol) in homogeneous dimethylsulfoxide solutions using a tri-ethylamine catalyst. These modified polymers are soluble in dimethyl sulfoxide, dimethylacetamide, dimethylformamide and formic acid but are insoluble in water, methanol and xylene. Above about 50% degree of substitution, the polymers are also soluble in acetic acid and butyrolactone. The modified polymers contain aromatic, C = 0, NH and CN bands in the infrared and show a diminished OH absorption. Similar results were noted in the NMR spectroscopy. These modified polymers show a lower specific and intrinsic viscosity in DMSO solutions than does the unmodified poly(vinyl alcohol) and this viscosity decreases as the degree of substitution increases. 

The neurochemical basis for these effects has also heen studied in some detail. Researchers have learned that MDMA (and its phenyl-ethylamine cousins) interferes with the normal function of at least two neurotransmitters in the brain, serotonin and dopamine. Under normal circumstances, nerve messages are transmitted through the CNS when an axon on one neuron releases a neurotransmitter, such as serotonin or dopamine, which travels across the synapse between two neurons and is taken up at a receptor site in the second neuron. 

When rotation occurs about a bond there are two sources of strain energy. The first arises from the nonbonded interactions between the atoms attached to the two atoms of the bond (1,4-interactions) and these interactions are automatically included in most molecular mechanics models. The second source arises from reorganization of the electron density about the bonded atoms, which alters the degree of orbital overlap. The values for the force constants can be determined if a frequency for rotation about a bond in a model compound can be determined. For instance, the bond rotation frequencies of ethane and ethylamine have been determined by microwave spectroscopy. From the temperature dependence of the frequencies, the barriers to rotation have been determined as 12.1 and 8.28 kJ mol-1, respectively1243. The contribution to this barrier that arises from the nonbonded 1,4-interactions is then calculated using the potential functions to be employed in the force field. 

Vanadate reacts only very weakly with aliphatic amines such as ethylamine. As a consequence, reactions with aliphatic amines have not been extensively studied, but the information available suggests the reactions are analogous to those of alcohols. Additionally, there have been numerous studies of multidentate ligands where amino functionality is a critical component of vanadium ligation (Section 4.4). 

Compounds with a terminal acetylenic function, RCsCH, react with 1-bromoalkynes, R CsCBr in the presence of an aliphatic amine and a catalytic amount of a copper salt to give the coupling products RCsCCsCR. This useful reaction, discovered by Cadiot and Chodkiewicz [195], gives a ready access to a number of poly-unsaturated systems. The usual procedure involves dropwise addition of the bromoacetylene R GsCBr to a mixture of the acetylene RCsCH, ethylamine, ethanol or methanol, a catalytic amount of copper chloride or bromide and a small amount of hydroxylamine.HCl. This reducing agent prevents the oxidation to copper ). The reaction is usually very fast at temperatures in the region of 30 C. Since much heat is evolved, the reaction can be monitored easily by temperature observation. 

The excretion of amines is unusual in animals. Amines are highly toxic and one method employed by vertebrates to detoxify them is via monoamine oxidase, an enzyme which has been detected in H. diminuta (569). Amines can arise from the decarboxylation of the appropriate amino acid, e.g. glycine and alanine can give rise to methylamine and ethylamine, respectively. Another possible source of amines may be the reduction of azo or nitro compounds (39) and azo- and nitro-reductase activity has been reported from M. expansa (180, 181). Furthermore, the physiologically active amines octopamine, dopamine, adrenalin and serotonin (5-hydroxytryptamine) have been demonstrated in cestodes (283, 296, 435, 681, 682, 758, 859), where they probably function predominantly as neurotransmitters (see Chapter 2). 

Figure 1. Yield of pentasil zeolites (percentage crystallization) as a function of time. Abbreviations are C, for mono-n-butylair ne, CU for mono-n-propylamine, C2 for mono-n-ethylamine, C. for mono-n-methylamine, di-C, for di-n-propylamine, di-C, for di-n-propylamine,+di-C2 for di-n-ethylamine, di-n-C.. for di-n-methylamine, TPA Al-free for the aluminium-free synthesis with the tetrapr pylammonium cation, TPA for tetrapropylammonium cation, TEA Al-free for the+aluminium-free synthesis with the tetraethylammonium cation, TEA for tetraethylammonium cation and tri-C for tri-n-propylamine.

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