Attempts to improve the overall stereoselectivity of the Ireland-Claisen rearrangement.
With focus on the steric effects present in the transition states for the [3,3]-sigmatropic rearrangement, the substrate 5 has been designed to improve the overall stereoselectivity of the Ireland-Claisen rearrangement. Experimentally, it has been found that (1) only Z-6 rearranges to 7 at 80 degrees C and (2) E-6 isomerizes to Z-6 at 80 degrees C, thereby allowing the transformation of 5 into 7 in an almost quantitative yield. To illustrate the usefulness of this approach, two additional examples are given.
Chen
Chi-Li
CL
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Namba
Kosuke
K
Kishi
Yoshito
Y
D002125:Calcium Gluconate / Q000737:chemistry; D004988:Ethers, Cyclic / Q000737:chemistry; D005690:Galactose / Q000031:analogs & derivatives / Q000737:chemistry; D018942:Macrolides; D013237:Stereoisomerism; D013379:Substrate Specificity; D000095662:Polyether Polyketides
D002125:Calcium Gluconate; D004988:Ethers, Cyclic; D005690:Galactose; D018942:Macrolides; C070519:halichondrin B; D000095662:Polyether Polyketides; C002038:galactal