ASYMMETRIC-SYNTHESIS .39. SYNTHESIS OF 2-(1-AMINOALKYL)PIPERIDINES VIA 2-CYANO-6-PHENYL OXAZOLOPIPERIDINE

The asymmetric synthesis of a series of 2-(1-aminoalkyl) piperidines u sing (-)-2-cyano-6-phenyloxazolopiperidine 1 is described. LiAlH4 redu ction of 1 followed by hydrogenolysis led to the diamine 3. The same s trategy applied to C-2-methylated compound 7 afforded [(2S)-2-methylpi peridin-2-yl]methanamine (9). Addition of lithium derivatives to the c yano group of 1 resulted in the formation of an intermediate imino bic yclic system (11a-c) which could be diastereoselectively reduced to su bstituted diamino alcohols 13a-c. The addition of an excess of PhLi to 1 in the presence of LiBr furnished disubstituted amine 19, the precu rsor of diphenyl[(2S)-piperidin-2-yl]methanamine (22).