Acetophenone, 2-amino-, hydrochloride

Pioneering studies on the asymmetric hydrogenation of a-amino ketones have been done by Kumada and Achiwa [3, 4]. Achiwa s MCCPM/Rh complex catalyzed the reaction of 2-(dimethylamino)acetophenone hydrochloride with an Si C of 100,000 under 20 atm of H2 to give the corresponding chiral amino alcohol in 96% ee [32], although the reactions of other amino ketones showed less satisfactory rates and enantioselectivity. 

Amino-l-(3-hydroxyphenyl)ethanol has been prepared by an improved and possibly general method for this class of compounds.16 An interesting report on the partial asymmetric induction in the reduction of acetophenone-N-benzylimine at the mercury cathode with chiral supporting electrolytes may have potential for the chiral synthesis of alkaloids.17 For example, using ( -)-(R, S)-JV-methyI-ephedrine methiodide as the electrolyte resulted in the formation of (—)-(R)-N-benzyl-a-phenethylamine of 7.3% optical purity. Of interest for biosynthetic studies are the reports of the preparation of specifically labelled substituted -phenethylamines18 and of (+)-N-(o-chlorobenzyl)-a-methylphenethylamine hydrochloride 14C-labelled at the -carbon.19... 

Instead of a,/ -unsaturated ketones, the products of Mannich reactions, such as the hydrochloride resulting from the condensation of acetophenone, formaldehyde, and dimethylamine, may be used in a one-pot reaction together with 6-amino-l,3-dimethyluracil in refluxing acetic acid.266... 

Amino- 1-phenyl-athanol-Hydrochlorid4 Eine ges. Losung von 23 g (0,13 Mol) to-Amino-acetophenon-Hydrochlorid in 95%-igem Athanol wird in Gegenwart von 0,52 g Platinschwarz bei 3 bar hydriert. Es werden insgesamt —0,15 Molaquivalente Wasserstoff verbraucht. Man filtriert vom Katalysator ab und dampft das Fil-trat i. Vak. ein Ausbeute 22 g (97% d.Th.) F 176-177° (Zers.)... 

Analog erhalt man aus -Amino-3,4-dimethoxy-acetophenon-Hydrochlorid in fast quantitativer Ausbeute 2-Amino-l-(3,4-dimethoxy-phenyl)-dthanol-Hydrochlorid (F 168-170°, aus Athanol). 

Chlor-2-amino-acetophenon5 40 g (0,2 Mol) 4-Chlor-2-nitro-acetophenon werdenin 100m/ abs. Athanol gelost und mit 0,2 g Adams-Katalysator bis zur Aufnahme der ber. Menge Wasserstoff bei 2072-3 bar hydriert. Das ausgefallene Amin-Hydrochlorid wird abgesaugt und das Amin daraus mit Natriumcarbonat in Freiheit ge-setzt. AnschlieBend wird aus Benzol/Petrolather umkristallisiert Ausbeute 21,7 g (64°/0 d.Th.) F 90-91°. 

Amino cyanides are obtained by the action of ammonia and hydrocyanic acid, or of ammonium chloride and sodium cyanide, on aldehydes, or alternatively from cyanohydrins and ammonia. They are best hydrolysed by concentrated hydrochloric acid, the resulting amino acids being then obtained as hydrochlorides, whence the free amino acids can be liberated by means of lead monoxide, ammonia, or pyridine. For a critical consideration of the hydrolysis of amino cyanides see Cocker and Lapworth.632 The synthesis of DL-alanine has been detailed twice.780 633 That of racemic ac-amino-ac-phenyl-propionic acid from acetophenone, sodium cyanide, and ammonium chloride by way of the amino cyanide was worked out by Steiger.634 /9-Alanine is obtained in 85-90% yield when 3-aminopropionitrile is added to aqueous barium hydroxide at 90-95° during 40 min and kept at that temperature for a further 40 min.635... 

Lehmann and co-workers performed Maimich reactions with paraformaldehyde, secondary amines as their hydrochloride salts, and substituted acetophenones as the starting constituents [29]. With dioxane as solvent they performed reactions for 10 min at 180 °C to give the desired j8-amino ketones in moderate to good yields (Scheme 3.9). The syntheses were scaled-up twentyfold. A monomodal reactor was used for small-scale preparations and a multimodal system for scale-up. 

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