Synthesis of optically active 2-ethyl-1,6-dioxaspiro[4.4]nonane (chalcogran), the principal aggregation pheromone of pityogenes chalcographus (l.)

Synthesis of Functionalized 2-Alkylidenetetrahydrofurans by Cyclization of 1,3-Bis(trimethylsilyloxy)-1,3-butadienes with Epoxides

“…Synthesis of 2,3′‐bifuranylidenes : The extension of our methodology to the preparation of dinuclear 2‐alkylidenetetrahydrofurans (2,3′‐bifuranylidenes) was of special interest since these compounds are present in a number of natural products (see Introduction) 19. In addition, these compounds represent versatile building blocks for the synthesis of naturally occurring spiroketals such as chalcogran 22. Silylation of γ ‐butyrolactones 4 a,b with Me 3 SiCl/NEt 3 afforded the silyl enol ethers 5 a,b , which were transformed in high yields into the bis‐silyl enol ethers 6 a,b by treatment with LDA (lithium diisopropylamide) and Me 3 SiCl (Scheme ) 23…”

Transformations of peroxide products of olefins ozonolysis

“…The reduction of the peroxide ozonolysis products of p-menthene 133 under the same conditions gave hydroxyketone 201 chemoselectively converted further into isopropyl (4R)-methyl-6-iodohexanoate 202, a semiproduct in the synthesis of a number of optically pure isect pheromones [105][106][107] (Scheme 44).…”

Chiral Synthesis of Furanosesquiterpene, (+)-Ipomeamarone

“…(20) and (2S*,SS*)-5-(3-FuryI)-2-methyl-2-(2-propenyl)oxolane (21) p-TsC1 (5.089 g, 25.89 mmol) was added to a stirred solution of (*)-I7 (5.179 g, 24.63 mmol) in dry pyridine (36 ml) under ice cooling and the reaction mixture was stirred at 0 OC for 30 min and at room temperature for 14.5 h. After addition of chloroform (180 ml), the mixture was washed with water (90 ml), 5% HCI (360 ml), 10% HCl(180 ml) and water (180 ml), successively. (20) and (2S*,SS*)-5-(3-FuryI)-2-methyl-2-(2-propenyl)oxolane (21) p-TsC1 (5.089 g, 25.89 mmol) was added to a stirred solution of (*)-I7 (5.179 g, 24.63 mmol) in dry pyridine (36 ml) under ice cooling and the reaction mixture was stirred at 0 OC for 30 min and at room temperature for 14.5 h. After addition of chloroform (180 ml), the mixture was washed with water (90 ml), 5% HCI (360 ml), 10% HCl(180 ml) and water (180 ml), successively.…”