Patent GB-817353-A (GB)
Title: New piperidines and process for their manufacture
IPC: A61K31/00
Filed: 1955-09-20
Abstract: The invention comprises piperidine compounds of the formula <FORM:0817353/IV (b)/1> (wherein R is hydrogen or an alkyl radical containing at most 3 carbon atoms, R1 is an alkyl radical containing at most 6 carbon atoms, and the phenyl group may be substituted by an alkyl radical containing at most 3 carbon atoms or a halogen atom) and their acid-addition salts; and their preparation by the methods detailed below.  In examples: (1) phenyl-pyridyl-(2)-acetonitrile and methyl iodide are condensed in dioxan containing sodamide and the product is hydrolysed and decarboxylated with strong sulphuric acid to give 2-(11-phenyl-ethyl)-pyridine, which on hydrogenation in glacial acetic acid in the presence of platinum oxide at 40 DEG  C. yields 2 - (11 - phenyl - ethyl) - piperidine (hydrochloride also described); (2) the product of (1) is heated with formaldehyde and formic acid to give 2-(11-phenyl-ethyl)-1-methyl-piperidine (picrate also described); (3) 2-(11-phenyl-ethyl)-1-methyl-pyridinium methosulphate (prepared from the N-unsubstituted pyridine and dimethyl sulphate) is hydrogenated in methanol in the presence of platinum oxide at room temperature to give the product of (2); (4) 2-(11-phenyl-propyl)-pyridine, prepared as the corresponding ethyl compound in (1) from phenyl-pyridyl-(2)-acetonitrile and ethyl bromide, is hydrogenated in glacial acetic acid in the presence of platinum oxide to give 2-(11-phenyl-propyl)-piperidine, the diastereoisomeric forms of which are separated by fractional crystallization of their hydrochlorides or of their picrates; (5) phenyl-pyridyl-(2)-acetonitrile and n-propyl bromide give 2-(11-phenyl-butyl)-pyridine, which on reduction as in (5) gives the corresponding piperidine (hydrochloride also described); (6) 2-bromopyridine and phenyl-isopropylacetonitrile give 2 - (11 - phenyl - 21 - methyl) - propyl - pyridine, which is reduced to the corresponding piperidine (hydrochloride also described); (7) and (8) 2-(11 - para - chlorophenyl - 21 - methyl - propyl) - pyridine and 2 - (11 - phenyl - 31 - methyl - butyl) - pyridine and the corresponding piperidines and the hydrochlorides thereof are similarly prepared; (9) 2-(11-phenyl-41-methyl-pentyl)-pyridine is similarly prepared and is similarly reduced to the corresponding piperidine, the hydrochloride of which is separated by fractional crystallization into two diastereoisomeric forms; (10) 2-(11-phenyl-11-hydroxy-ethyl)-piperidine is heated with strong sulphuric acid to give 2 - (11 - phenyl - ethylidene) - piperidine (picrate also described) and this on reduction as above gives the product of (1); (11) acetophenone is heated with pyridine in the presence of aluminium and traces of mercuric chloride, mercury and iodine to give the starting material of (10), and this is reduced with sodium and amyl alcohol to give the product of (1); (12) cyanethyl - malonic acid di - (2:3:5:6 - tetrahydropyranyl-(2) ester) is reacted with a -phenyl-butyric acid chloride in presence of sodium hydride in benzene at 30 DEG  C., the condensation product is decomposed by boiling with glacial acetic acid to give 6-phenyl-5-oxo-octanoic acid nitrile-(1) (2:4-dinitro-phenyl-hydrazone described), this is hydrogenated with nickel catalyst on earthenware in alcohol at 100 atmospheres and the product is heated with concentrated HCl to give, on working up, 2-(11-phenyl-propyl)-D 1,2-piperideine (picrate described) which on hydrogenation with platinum oxide in acetic acid gives the product of (4); and (13) the reduction process of (1) is effected with palladium-charcoal in isopropanol.  The use of copper chromite as a reduction catalyst is also referred to.  A list of acids suitable for forming acid-addition salts according to the invention is also given. Specification 754,372 is referred to.ALSO:A pharmaceutical preparation, suitable for enteral, parenteral or oral administration, comprises a piperidine compound of the formula <FORM:0817353/VI/1> (wherein R is hydrogen or an alkyl radical containing at most 3 carbon atoms, R1 is an alkyl radical containing at most 6 carbon atoms, and the phenyl group may be substituted by an alkyl radical containing at most 3 carbon atoms or a halogen atom) or an acid-addition salt thereof in admixture with a pharmaceutical carrier such as gelatine, lactose, starch, magnesium stearate, talc, vegetable oils, benzyl alcohols, gums, polyalkylene glycols, petroleum jelly or cholesterol.  The preparations may take the form of, for example, tablets, dragees, solutions, suspensions or emulsions, and they may contain auxiliary substances such as preservatives, stabilizing, wetting or emulsifying agents, salts for the variation of osmotic pressure, buffer substances or other therapeutically valuable substances.  Examples describe a tablet containing 2-(11-phenyl-propyl)-piperidine hydrochloride and a preparation suitable for charging into ampoules containing 2 - (11- phenyl - butyl) - piperidine hydrochloride, sodium chloride, secondary sodium phosphate, primary sodium phosphate and water. Specification 754,372, [Group IV (b)], is referred to.