Pestalotiopsin A. Side chain installation and exhaustive probing of olefin metathesis as a possible tool for elaborating the cyclononene ring.
A program directed toward an asymmetric synthesis of pestalotiopsin A is described. The routing begins with the dextrorotatory cyclobutanol 37, which is combined with the enantiomerically defined building blocks ent-15 and 16. These units are incorporated via stereocontrolled 1,2-nucleophilic addition and anti-aldol coupling, respectively. With these straightforward reactions accomplished, the sequel involved the introduction of terminal double bonds in anticipation of the fact that the (E)-cyclononene substructure could be realized by ring-closing metathesis. This central issue was evaluated with several diene substrates and catalysts, all to no avail. Cross-metathesis experiments involving 59 and 65 with the functionalized heptene 60 revealed a marked difference in the inability to engage interaction with the ruthenium catalyst. This awkwardness could not be skirted.
Paquette
Leo A
LA
Evans Chemical Laboratories, The Ohio State University, Columbus, OH 43210, USA. paquette.1@osu.edu
Dong
Shuzhi
S
Parker
Gregory D
GD
D001643:Bridged Bicyclo Compounds / Q000737:chemistry; D003500:Cyclization; D003516:Cycloparaffins / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry; D012717:Sesquiterpenes / Q000138:chemical synthesis*
D001643:Bridged Bicyclo Compounds; D003516:Cycloparaffins; D007783:Lactones; D012717:Sesquiterpenes; C430595:pestalotiopsin A