6533b833fe1ef96bd129cac0

RESEARCH PRODUCT

Stereoselective Total Synthesis of the Diastereomeric Tricyclic Alkaloids Tetraponerine-7 and Tetraponerine-8 Using O-Pivalo­ylated d-Arabinopyranosylamine as the Common Auxiliary

subject

description

Based on a diastereoselective domino Mannich–Michael reaction cascade of 2- N -[( S )-3-{(benzyloxycarbonyl)[4-( tert -butyldiphenylsiloxy)butyl]amino}octylidene]-2,3,4-tri- O -pivaloyl-α- d -arabinopyranosylamine with the Danishefsky diene, the major component of the neurotoxic venom of the New Guinean ant Tetraponera punctulata , tetraponerine-8, and its diastereomer tetraponerine-7 were synthesized in pure form. While the Mannich reaction of the arabinosyl imine of the required ( S )-configured β-aminoaldehyde gave the 2-substituted piperidinone precursor of tetraponerine-8 with excellent diastereoselectivity, the analogous Mannich reaction of the ( R )-configured β-aminoaldehyde afforded the precursor of tetraponerine-7 with a selectivity of only 2:1 (mismatched case). The enantiomerically pure tetraponerine-8, described as highly toxic for ants, exhibited only moderate toxicity to sucking and stinging insects.