1.2- Dimethyl-4-phenylpiperidin

Reduction of o /i-unsatin-ated lactams, S,6-dihydro-2-pyridones, with lithium aluminum hydride, lithium alkoxyaluminum hydrides and alane gave the corresponding piperidines. 5-Methyl-5,6-dihydro-2-pyridone (with no substituent on nitrogen) gave on reduction with lithium aluminum hydride in tetrahydrofuran only 9% yield of 2-methylpiperidine, but l,6-dimethyl-5,6-dihydro-2-pyridone and 6-methyl-l-phenyl-5,6-dihydro-2-pyridone afforded 1,2-dimethylpiperidine and 2-methyl-1-phenylpiperidine in respective yields of 47% and 65% with an excess of lithium aluminum hydride, and 91% and 92% with alane generated from lithium aluminum hydride and aluminum chloride in ether. Lithium mono-, di- and triethoxyaluminum hydrides also gave satisfactory yields (45-84%) [7752]. 

Dimethyl l,2,6-trimethyl-4-phenylpiperidine-3,5-dicarboxylate (130) with paraformaldehyde and methylamine hydrochloride gave dimethyl 2,6,7-trimethyl-4-phenyl-l,4,4a,5,6,7-hexahydro-l,6-naphthyridine-2,4a-dicarboxylate (131) (reactants, CHC13, reflux, 26 h 30%) 1210 also analogous condensations532,1210... 

H-nmr spectroscopy readily enables the differentiation of chiral from achiral (meso) diastereoisomers of 3,5- and 2,6-dimethyl-4-phenylpiperidines because in the meso forms the two methyls have identical environments and give rise to the same resonance, while chiral isomers involve an axial-equatorial pair that results in two separate methyl signals (see 39). The configurations of both the chiral 2,6- and 3,5-dimethyl reversed ester analogs of pethidine have been confirmed by X-ray crystallography/27 41)... 

Casy and McErlane have reported synthetic and stereochemical studies on the l,2-dimethyl-4-phenylpiperidin-4-ols (357), and on the 3-methyl-4-phenylpiperidines (358). By comparison of the i.r. spectra of [ N]- and... 

NaNHj added in small portions under anhydrous conditions to a mixture of benzyl cyanide, ethyl bis-(/ -dilorethyl)carbamate, and dry dimethyl sulfoxide, while the temp, rises to 50°, stirring continued 0.5 hr. l-carbethoxy-4-cyano-4-phenylpiperidine. Y 85-99%. C.V.Bercz and R. D.Ice, J. Pharm. Sci. 61, 1316 (1972). 

H19N3, (2,6-cis-Dimethylpiperidyl)diazobenzene, 44B, 214 3H20CINO, 1,2-Dimethyl-4-hydroxy-4-phenylpiperidine hydrochloride, 40B, 230... 

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