Stereocontrolled synthesis of all of the four possible stereoisomers of erythro-3,7-dimethyl-pentadec-2-yl acetate and propionate, the sex pheromone of the pine sawflies

Abstract

Die vier Stereoisomeren (Ia)‐(Id) werden synthetisiert und a) in die jeweiligen Acetate (IIa) sowie b) in die jeweiligen Propionate (IIb) übergeführt, die auf ihre Pheromonaktivität (Kiefem‐Sägewespe (Hymenoptera: Diprionidae)) getestet werden sollen: 1. Ausgehend von der D‐Weinsäure (IIIa) wird über die Stufen (IIIb), (IVa) (bekannte Reaktionen), (IVb)‐(IVe), (V) und (VI) das Epoxid (VII) dargestellt.

Counterion Effects on the Mesomorphic Properties of Chiral Imidazolium and Pyridinium Ionic Liquids

“…Compounds 17 were submitted to ozonolysis in CH 2 Cl 2 /MeOH at -78°C followed by reductive work-up with NaBH 4 [12] to give the alcohols 18 in 68-80 % yields. Subsequent treatment with PBr 3 yielded the bromides 19 in 71-93 % yields, which were converted into the N-methylimidazolium bromides 4d-8d and pyridinium bromides 10d-14d by heating 19 with N-methylimidazole or pyridine in hexane at 60°C for 2-3 d. Whereas the N-methylimidazolium bromides 3a-f were formed within 2 d and were isolated in good yields (77-93 %), the corresponding pyridinium bromides 9a-d required 3 d for complete conversion and only moderate yields (36-56 %) were obtained.…”

“…[10b] The following derivatives are known: 17a-19a, [12] 17c, [16] 17e, [17] 17f, [18] 18c,e [19] and 18f. [20] General Procedure for the Reaction of Tosylate 16 with Cuprates: 1-Bromoalkene (47.0 mmol) in THF (80 mL) was added dropwise to a suspension of Mg turnings (1.42 g, 58.3 mmol) in THF (10 mL) so that a steady reflux of the mixture was maintained.…”

Composition of the Cloacal Gland Secretion of Tuatara, Sphenodon punctatus

“…The resulting diyne ester 25 was then partially hydrogenated using P-2 nickel to obtain the desired methyl ester 26. Both synthetic methyl esters were identical to those of the natural acids G and H. (27), which was tosylated with TsCl, converted to the nitrile 29 using NaCN, and hydrolyzed with NaOH to yield the acid 30 (Scheme 5), as previously reported for (R)-30 by Mori and Tamada [29]. The methyl ester of this compound proved to have the same constitution as methyl-J and could be used for the determination of the absolute configuration of the natural acid (see below).…”

“…(S)-3,7-Dimethyloct-6-enyl Toluenesulfonate (28). The toluenesulfonate 28 was prepared as described by Mori and Tamada [29], using (À)-(S)-3,7-Dimethyloct-6-en-1-ol (27) (7)); 119.9 (s, C(1)); 36.2 (t, C(5)); 32.2 (t, C(3)); 31.5 (d, C(4)); 25.6 (q, C(9)); 25.2 (t, C(6)); 18.6 (q, MeÀC(4)); 17.6 (q, MeÀC (8) 2 HÀC(6)); 1.75 -1.64 (m, 1 H, HÀC(3)); 1.68 (d, J ¼ 1.1, 3 HÀC(9)); 1.60 (d, J ¼ 0.4, MeÀC(8)); 1.52 -1.40 (m, 1 HÀC(3), HÀC(4)); 1.38 -1.12 (m, 2 HÀC(5)); 0.90 (d, J ¼ 6.4, MeÀC(4)). 13 C-NMR (100 MHz, CDCl 3 ): 180.7 (s, C(1)); 131.3 (s, C (8)); 124.6 (d, C (7)); 36.7 (t, C(5)); 32.0 (d, C(4)); 31.9 (t, C(2)); 31.5 (t, C(3)); 25.7 (q, C(9)); 25.4 (t, C(6)); 19.1 (q, MeÀC (4)); 17.6 (q, MeÀC (8)).…”

Readily Available Chiral Carbon Fragments and Their Use in Synthesis

“…One-carbon homologation of 986 in four steps gave ester 1000, the epoxidation and oxidation of which led to aldehyde 1001 (90). Oxidation to the acid and Hunsdiecker reaction removed one carbon to give bromide 1002.…”