Asymmetric syntheses of panclicins A–E via [2+2] cycloaddition of alkyl(trimethylsilyl)ketenes to a β-silyloxyaldehyde
作者:Philip J. Kocieński、Beatrice Pelotier、Jean-Marc Pons、Heather Prideaux
DOI:10.1039/a800807h
日期:——
Panclicins AâE, pancreatic lipase inhibitors from Streptomyces, were synthesised in a modular fashion starting with three alkyl(trimethylsilyl)ketenes, two amino acids and a single aldehyde component, (3R)-3-(tert-butyldimethylsilyloxy)decanal 11. The lone stereocentre in 11 which governs the stereochemistry in subsequent steps was generated by Noyori asymmetric hydrogenation. The key step, a Lewis acid catalysed [2+2] cycloaddition of alkyl(trimethylsilyl)ketenes 13aâc to 11, gave three 3-trimethylsilyloxetan-2-ones with good 1,3-asymmetric induction. After C- and O-desilylation the amino acid side chains were introduced using a Mitsunobu inversion.