Synthesis of (2,3,1',2')-stegobiol, a new component of the drugstore beetle pheromone

Synthesis of Stegobiol and Its Oxidation to Stegobinone, the Components of the Female-Produced Sex Pheromone of the Drugstore Beetle

“…When the TBS protective group of 16 was deprotected by treatment with hydrofluoric acid in acetonitrile, stegobiol (2) was obtained in 47% yield. Pure stegobiol was indeed crystalline as reported by Matteson et al [11] [12] [13] , although Kodama et al [2] and also ourselves [7] reported it to be oily. Finally we carefully examined the oxidation of stegobiol (2) to stegobinone (1) so as to find out the proper conditions to obtain 1 as crystals.…”

“…The overall yield of 14 was 5.4% based on 6 (10 steps) or 10.4% based on 7 (8 steps). In our previous synthesis of 14 [7] , it was prepared from octyl (S)-3-hydroxypentanoate in 5.4% overall yield (6 steps). Octyl (S)-3-hydroxypentanoate (97% e.e.)…”

“…According to the reported procedure [6] [7] 4 and 14 were coupled to give the known ester 15 (ϭ E) [7] . Cyclization of 15 to stegobiol TBS ether was executed previously by employing lithium hexamethyldisilazide [7] . As criticized by Oppolzer [8] , however, this procedure was very difficult to be reproduced.…”

“…These spectral data were in good accord with those reported in ref. [7] . (16): A 0.5  solution of TiCl 4 in CH 2 Cl 2 (21.5 ml, 10.8 mmol) was added dropwise at Ϫ78°C to a solution of 15 (770 mg, 2.15 mmol) and ethyldiisopropylamine (2.68 ml, 17.2 mmol) in CH 2 Cl 2 (92 ml).…”

Synthesis of 1′-Epi-stegobinone

“…and brine, dried (MgS04) and concentrated in vacuo. (4). To a solution of 10 (300 mg, 0.84 mmol) in dry THF (15 ml) and TMEDA (13 ml) was slowly added dropwise a solution of lithium hexamethyldisilazide in dry THF (0.34 M, 2.47 ml, 0.84mmol) with stirring at -'70°C under Ar.…”