In Pursuit of Pestalotiopsin A via Zirconocene-Mediated Ring Contraction
摘要:
[graphics]An asymmetric route from the epimeric,- hydroxy esters 4 and 5 to the densely functionalized (+)-10 and (-)-10, respectively, is described. Either cyclobutanol can be made available as the predominant product. The levorotatory antipode has been transformed into the advanced intermediate 21 bearing side chains destined to become incorporated into the cyclononene ring of the title compound (1).
Pestalotiopsin A. Enantioselective Construction of Potential Building Blocks Derived from Antipodal Cyclobutanol Intermediates
摘要:
[GRAPHICS]D-Glyceraldehyde acetonide has been used as the starting point for accessing the enantiomeric cyclobutanols 11 in optically pure condition. The dextrorotatory enantiomer has been transformed in five steps into the [3.2.0] bicyclic lactone 22. While the deoxygenation of 22 proved to be problematical, the uncyclized variant 25 underwent the Barton process smoothly. These findings guided the related conversion of (-)-11 into 34. Use was also made of ring-closing metathesis to bring about the conversion of (+)-11 into [4.2.0] bicyclic lactone building blocks. In general, all three pathways are efficient and offer the prospect of practical side-chain appendage for the purpose of installing the nine-membered ring of pestalotiopsin A (1).
In Pursuit of Pestalotiopsin A via Zirconocene-Mediated Ring Contraction
作者:Shuzhi Dong、Gregory D. Parker、Takahiro Tei、Leo A. Paquette
DOI:10.1021/ol060827j
日期:2006.5.1
[graphics]An asymmetric route from the epimeric,- hydroxy esters 4 and 5 to the densely functionalized (+)-10 and (-)-10, respectively, is described. Either cyclobutanol can be made available as the predominant product. The levorotatory antipode has been transformed into the advanced intermediate 21 bearing side chains destined to become incorporated into the cyclononene ring of the title compound (1).
Pestalotiopsin A. Enantioselective Construction of Potential Building Blocks Derived from Antipodal Cyclobutanol Intermediates
作者:Leo A. Paquette、Gregory D. Parker、Takahiro Tei、Shuzhi Dong
DOI:10.1021/jo070861r
日期:2007.9.1
[GRAPHICS]D-Glyceraldehyde acetonide has been used as the starting point for accessing the enantiomeric cyclobutanols 11 in optically pure condition. The dextrorotatory enantiomer has been transformed in five steps into the [3.2.0] bicyclic lactone 22. While the deoxygenation of 22 proved to be problematical, the uncyclized variant 25 underwent the Barton process smoothly. These findings guided the related conversion of (-)-11 into 34. Use was also made of ring-closing metathesis to bring about the conversion of (+)-11 into [4.2.0] bicyclic lactone building blocks. In general, all three pathways are efficient and offer the prospect of practical side-chain appendage for the purpose of installing the nine-membered ring of pestalotiopsin A (1).