Synthesis of (3aR,8S,8bS,2′R)-(+)-sorgolactone and its stereoisomers, the germination stimulant from sorghum bicolor
作者:Kenji Mori、Junichi Matsui
DOI:10.1016/s0040-4039(97)10078-8
日期:1997.11
Methyl (S)-citronellate (2) was converted to (3aR,8S,8bS,2′R)-(+)-sorgolactone (1a) by employing the radical cyclization of 6 to 7 as the key-step. Three other stereoisomers (1b, 1c and 1d) of sorgolactone were also prepared. The CD spectrum of 1a was in accord with that reported for the natural product.
Synthesis and Biological Evaluation of the Four Racemic Stereoisomers of the Structure Proposed for Sorgolactone, the Germination Stimulant from Sorghum bicolor
The synthesis of the racemates of the structure 1 proposed for sorgolactone and its three stereoisomers was achieved by confirming the stereostructures of the intermediate (±)-6 and the final product (±)-1 by X-ray analyses. Biologicalevaluation of the products employing clover broomrape (Orobanche minor) seeds revealed that the order of activity as a germinationstimulant was (±)-strigol ≈ (±)-9
Synthesis of All Eight Stereoisomers of the Germination Stimulant Sorgolactone
作者:Yukihiro Sugimoto、Suzanne C. M. Wigchert、Jan Willem J. F. Thuring、Binne Zwanenburg
DOI:10.1021/jo9718408
日期:1998.2.1
The naturally occurring sesquiterpene sorgolactone (2) belongs to the class of "strigolactones", which are highly potent germination stimulants for seeds of the parasitic weeds Striga and Orobanche. The aim of the present work was to synthesize all eight stereoisomers of sorgolactone and to evaluate their activities in the stimulation of germination of S. hermontica and O. crenata. Two racemic diastereomers of the ABC part of sorgolactone, rac.10a and rac.10b respectively, were prepared and coupled with homochiral latent D-ring synthons 12 and ent.12. In this manner, four mixtures of two separable (protected) sorgolactone diastereomers were obtained. Deprotection gave all eight target compounds as single isomers. Bioassays revealed that only those isomers possessing the same stereochemistry as natural sorgolactone at two adjacent chiral centers exhibit high biological activities.