Stereoselective synthesis of 2,4,5-trisubstituted piperidines by carbonyl ene and Prins cyclisations.
Cyclisation of aldehydes 3-e catalysed by concentrated hydrochloric acid affords predominantly the all cis 2,4,5-trisubstituted piperidines 4a-ewhen the 2-substituent is small, while catalysis by MeAlCl2 in refluxing chloroform gives the trans piperidines 5a-e with diastereomeric ratios of up to 99:1.
Cariou
Claire A M
CA
School of Chemistry, University of Birmingham, Edgbaston, Birmingham, UK B15 2TT.
Snaith
John S
JS
D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D006851:Hydrochloric Acid; D010880:Piperidines / Q000138:chemical synthesis*; D013237:Stereoisomerism
D000447:Aldehydes; D010880:Piperidines; D006851:Hydrochloric Acid