CONCISE AND STEREOSELECTIVE SYNTHESES OF THE EIGHT NATURAL ANT DEFENSE ALKALOIDS (+)-TETRAPONERINE-1 TO (+)-TETRAPONERINE-8 ACCORDING TO THE CN(R,S) STRATEGY

摘要

The asymmetric syntheses of all the known defense alkaloids of the ant Tetraponera sp. tetraponerines T-1 to T-8 have been accomplished in five or six steps with 20-45% overall yields. The synthesis involved in the cross-condensation of (R)-piperidin-2-ylacetaldehyde with 4-aminobutyraldehyde which upon quenching by cyanide ion gave a stable tricyclic amino nitrile 3 with both a high yield and complete diastereoselectivity. This amino nitrile is the common precursor of four tetraponerines. A similar synthesis using (R)-pyrrolidine-2-ylacetaldehyde provided the tricyclic amino nitrile 2 precursor of the four other tetraponerines. [References: 26]