A straightforward procedure for the synthesis of enantiopure polysubstituted piperidines is reported. It involves the direct generation of chiral non-racemic oxazolo[3,2-a]piperidone lactams that already incorporate carbon substituents on the heterocyclic ring and the subsequent removal of the chiralauxiliary. The key step is a cyclocondensation reaction of (R)-phenylglycinol or other amino alcohols
The first synthesis of the marine indolizidine alkaloids, (+)-stellettamide A and (-)-stellettamide C, has been achieved through a coupling reaction with the aminomethylindolizidine fragment and the chiral or achiral trienecarboxylic acid fragment, both of which could be derived from farnesol as a common precursor.
Total Synthesis of (−)-Stellettamide B and Determination of Its Absolute Stereochemistry
[figure: see text] The first total synthesis of (-)-stellettamide B has been achieved by a sequence based on amide coupling of the chiral 1-(aminomethyl)-indolizidine fragment, prepared by TiCl4-mediated asymmetric allylation of the tricyclic N-acyl-N,O-acetal, with the chiral trienoic acid fragment. This synthesis led to revision of the published relative stereochemistry of the natural product and established