Marius Sutter

Two enantioselective syntheses of a precursor of the biologically most active isomer of CGA 80000 (clozylacon)

Abstract The unchlorinated precursor 4 of CGA 80000 ( 1 ) was synthesized enantioselectively by two conceptionally different routes: a) by a “chiral pool” approach starting from L-malic acid and b) by enantioselective hydrogenation of an enamide intermediate, catalyzed by chiral Rh- or Ru-phosphine-complexes.

First total synthesis of strobilurin B

Abstract A general approach to the synthesis of all known strobilurins - a class of natural products - is outlined with strobilurin B as an example.

The stereoselective derivatisation of the Re or Si faces of the Δ9,10-double bond of soraphen A

Abstract The Δ 9,10 double bond of soraphen A was found to react selectively on the Si face, whereas the same double bond in the hydroxy-ketone tautomer of soraphen A is attacked on the Re face. It became possible to prepare products of chosen stereochemistry by stabilising the requisite tautomer by use of the appropriate protecting groups. Attempts at S N 2 displacements on the soraphen molecule failed and electrophilic addition to the Δ 9,10 double bond in our experiences never took place in a 1,2 manner. Based on these results and results with other macrolides, it is suggested that S N 1 reactions are more likely to succeed than S N 2 reactions in macrolide derivatisation.