Tandem [4 + 2]/[3 + 2] Cycloadditions of Nitroalkenes. 11. The Synthesis of (+)-Crotanecine
作者:Scott E. Denmark、Atli Thorarensen
DOI:10.1021/ja963084d
日期:1997.1.1
base component of a number of pyrrolizidine alkaloids. This necine subunit is an amino triol bearing a primary allylic alcohol characterized by an all-cis relationship of its stereocenters. The synthesis of (+)-crotanecine has been accomplished in 10 steps and 10.2% overall yield. The key step in the asymmetric synthesis is a Lewis acid-promoted, tandem inter[4 + 2]/intra[3 + 2] cycloaddition between
Tandem [4 + 2]/[3 + 2] Cycloadditions of Nitroalkenes. 9. Synthesis of (−)-Rosmarinecine
作者:Scott E. Denmark、Atli Thorarensen、Donald S. Middleton
DOI:10.1021/ja961630x
日期:1996.1.1
general approach for the construction of pyrrolizidines having this stereochemical feature. The key step in the asymmetric synthesis is a Lewisacid-promoted, tandem inter-[4 + 2]/intra-[3 + 2] cycloaddition between a fumaroyloxy nitroalkene and a chiral vinyl ether.