Asymmetric syntheses of (+)-negamycin, (+)-3-epi-negamycin and sperabillin C via lithium amide conjugate addition
Davies SG., Ichihara O., Roberts PM., Thomson JE.
The chemo- and enantioselective reduction of ethyl 4-chloroacetoacetate and the diastereoselective conjugate addition of enantiopure lithium N-benzyl-N-(α-methylbenzyl)amide to an α,β-unsaturated ester have been used as the key steps in the total asymmetric syntheses of (+)-negamycin (in 13 steps and 24% overall yield), (+)-3-epi-negamycin (in 13 steps and 10% overall yield) and sperabillin C (in 17 steps and 13% overall yield) from commercially available starting materials. © 2010 Elsevier Ltd. All rights reserved.