N-Cbz sulfilimines as valuable intramolecular nucleophiles for the stereoselective synthesis of (−)-deoxocassine and (+)-desoxoprosophylline
作者:Sadagopan Raghavan、Shaik Mustafa
DOI:10.1016/j.tet.2008.08.031
日期:2008.10
sulfilimine, prepared from the corresponding sulfoxide using the Burgess reagent, has been employed as an intramolecular nucleophile for the regio- and stereoselective preparation of a bromo-carbamate from an alkene. The bromo-carbamate has been utilized as an advanced common synthon for the synthesis of deoxocassine and desoxoprosophylline employing the ene and amidomercuration as key reactions.
A General Approach to (5<i>S</i>,6<i>R</i>)-6-Alkyl-5-benzyloxy-2-piperidinones: Application to the Asymmetric Syntheses of Neurokinin Substance P Receptor Antagonist (−)-L-733,061 and (−)-Deoxocassine
A generalapproach to (5S,6R)-6-alkyl-5-benzyloxy-2-piperidinones based on the regio- and diastereoselective reductive alkylation of (S)-3-benzyloxyglutarimide 7 is described. This method opens an entrance to chiral nonracemic substituted 3-piperidinols. The versatility of the method is illustrated by the asymmetric syntheses of neurokinin substance P receptor antagonist L-733,061 (ent-1), (−)-deoxocassine
(−)-Deoxocassine [(2R,3R,6S)-6-dodecyl-2-methyl-3-piperidinol] and its diastereomers with 2R-configuration were synthesized starting from d-alanine by a route involving the intramolecular aminomercuration of an ε,ζ-unsaturated amine.
Stereospecific route to enantiopure all cis-2,3,6-trisubstituted piperidines. Facile synthesis of (−)-deoxocassine and (+)-azimic acid
作者:Dawei Ma、Nan Ma
DOI:10.1016/s0040-4039(03)00820-7
日期:2003.5
of the enantiopure β-amino esters 10 provides the γ-amnio alcohol 11, which is condensed with 2,4-pentadione to afford 12. Stepwise cyclization of 12 produced the cyclic enamine 13, which is hydrogenated to deliver all cis-2,3,6-trisubstituted piperidine 14. Using this reaction sequence and subsequent Baeyer–Villiger oxidation as the key step (−)-deoxocassine and (+)-azimic acid are synthesized.