Abstract The title compund, 1a, has been synthesised in racemic form from ethyl (E)-4-chloro- 3-ethoxybut-2-enoate in 43% overall yield in five steps. Several routes to the final product are described, but the most efficient involves hydrogenation of a C (5)-unsubstituted tetramic acid 5b. The instability of this class of compounds required the use of a catalyst which could operate under very acidic aqueous conditions, a role that was successfully filled by a 5% ...
