[4 + 2]-Annulations of Chiral Organosilanes: Application to the Total Synthesis of Leucascandrolide A
作者:Qibin Su、Les A. Dakin、James S. Panek
DOI:10.1021/jo0610412
日期:2007.1.1
Complete details of an asymmetric synthesis of leucascandrolide A (1) are described. The synthesis highlights the use of two diastereoselective [4 + 2]-annulations for the assembly of the functionalized bispyranyl macrolide 3. An efficient assembly and union of the oxazole-containing side chain 4 with macrolide 3 was carried out using a Mitsunobu reaction. A convergent route to the oxazole side chain
Enantioselective [4 + 2]-Annulation of Chiral Crotylsilanes: Application to the Synthesis of a C1−C22 Fragment of Leucascandrolide A
作者:Les A. Dakin、James S. Panek
DOI:10.1021/ol035581m
日期:2003.10.1
[reaction: see text] The asymmetric synthesis of a C1-C22 fragment (2) of leucascandrolide A is described. Synthetic highlights include the construction of the C9-C22 pyran fragment using a formal [4 + 2]-annulation of a chiral organosilane. A diastereoselctive Mukaiyama aldol was used to introduce the C9 stereocenter and complete the assembly of the macrocycle's carbon skeleton.