entry toward thienamycin and related compounds. The copper(I)-mediated reaction between five-membered cyclic nitrones and terminal acetylenes, leading to the assembly of the basic skeleton of carbapenemantibiotics is described. The diastereoselectivity of this cycloaddition–rearrangement cascade, a process known as the Kinugasa reaction, with respect to the structure and configuration of both substrates
shifts of the H-2 proton and geminal protons of the protected alkoxymethyl group at the C-2 carbon atom. The differences of 1 H NMR chemical shifts of these protons fall in two ranges of about 3.3-3.7 ppm, and 4.0-4.4 ppm. This observation can be attributed to the influence of the anisotropy of the neighboring carbonylgroup and can be easily correlated with configuration at the bridgehead carbon atom
A novel synthesis of thienamycin is described. The crucial step of the synthesis is based on Cu(I)-mediated Kinugasa cycloaddition/rearrangement cascade reaction between terminal acetylene derived from D-lactic acid and suitable, partially protected, five-membered cyclic nitrone obtained from 2-deoxy-D-ribose. The reaction was performed in the presence of tetramethylguanidine as a base to provide 5