“…IR: 2925, 2855, 1465, 1440, 1215, 1150, 1110, 1045, 920 cm −1 ; 1 H NMR: 13,15-dioxahexadecanal (3). This compound was prepared using the procedure reported by Stowell (8). A mixture of 2 (3.10 g, 10 mmol), pyridine oxide (20 mmol), and sodium bicarbonate (20 mmol) in 50 mL of toluene was heated with vigorous stirring under a nitrogen atmosphere at 80°C for 24 h. The reaction mixture was allowed to cool, and 10 mL of water was then added.…”
The preparation and characterization of a series of deuterium-labeled intermediates used in the study of the biosynthetic pathway for disparlure, the sex pheromone of Lymantria dispar, is reported. The synthetic route starts with propargyl alcohol, and the deuterium atoms are introduced by deuteration of an alkyne precursor in the presence of Wilkinson's catalyst. The olefinic bond was created by the Wittig reaction of a suitable aldehyde with a common tetradeuterated phosphonium ylide intermediate. The presence of the expected label and its correct location were confirmed by both MS and 13C NMR. These compounds were successfully used to elucidate the disparlure biosynthetic pathway.
“…IR: 2925, 2855, 1465, 1440, 1215, 1150, 1110, 1045, 920 cm −1 ; 1 H NMR: 13,15-dioxahexadecanal (3). This compound was prepared using the procedure reported by Stowell (8). A mixture of 2 (3.10 g, 10 mmol), pyridine oxide (20 mmol), and sodium bicarbonate (20 mmol) in 50 mL of toluene was heated with vigorous stirring under a nitrogen atmosphere at 80°C for 24 h. The reaction mixture was allowed to cool, and 10 mL of water was then added.…”
The preparation and characterization of a series of deuterium-labeled intermediates used in the study of the biosynthetic pathway for disparlure, the sex pheromone of Lymantria dispar, is reported. The synthetic route starts with propargyl alcohol, and the deuterium atoms are introduced by deuteration of an alkyne precursor in the presence of Wilkinson's catalyst. The olefinic bond was created by the Wittig reaction of a suitable aldehyde with a common tetradeuterated phosphonium ylide intermediate. The presence of the expected label and its correct location were confirmed by both MS and 13C NMR. These compounds were successfully used to elucidate the disparlure biosynthetic pathway.
“…Hydrolysis and further oxidation (pyridinium dichromate) of the resulting cyclopropane derivative gave the final acid 1 . 1 Synthetic Route for the Cyclopropane Fatty Acids and Esters 1 and 2 a a Reagents and conditions: (a) CH 2 (OCH 3 ) 2 /LiBr/ p -TsOH/25 °C/16 h; (b) pyridine N -oxide/NaHCO 3 /toluene/reflux/4 h; (c) Ph 3 PCH 3 Br/ n -BuLi/THF/−20 °C/1.5 h, then add 11 in THF at −40 °C, then −40 → +25 °C and 2 h/reflux; (d) Et 2 Zn/CH 2 Cl 2 /−20 °C, then add CH 2 I 2 /−20 °C/1 h then −20 → +25 °C/48 h, then 10% HCl in MeOH/25 °C/14 h; (e) 0.2 M PDC/DMF/25 °C/6 h; (f) CH 2 N 2 /Et 2 O. 2 Synthetic Routes for the Cyclopropane Fatty Acids and Esters 3 − 8 a a Reagents and conditions: (a) NH 3 (l)/−78 °C, then add acetylene for 1.5 h, then add Li and DMSO, −78 → +25 °C, then add 14 in DMSO/25 °C/1 h; (b) n -BuLi/0 °C/5 min, then add R 1 I/0 °C/16 h; (c) H 2 /Lindlar/25 °C/1 h; (d) Na/NH 3 (l)/−78 °C/THF/10 min, then 8 h at −30 °C; (e) 10% HCl in MeOH/25 °C/16 h; (f) CrO 3 /H 2 O/H 2 SO 4 /acetone/25 °C/4 h; (g) BF 3 ·Et 2 O/ MeOH/25 °C/1 h; (h) Et 2 Zn/CH 2 Cl 2 /−20 °C, then add CH 2 I 2 /−20 °C/1 h then −20 → +25 °C/16 h; (i) 2.5N KOH/MeOH/H 2 O/25 °C/16 h. …”
Section: Resultsmentioning
confidence: 99%
“… a Reagents and conditions: (a) CH 2 (OCH 3 ) 2 /LiBr/ p -TsOH/25 °C/16 h; (b) pyridine N -oxide/NaHCO 3 /toluene/reflux/4 h; (c) Ph 3 PCH 3 Br/ n -BuLi/THF/−20 °C/1.5 h, then add 11 in THF at −40 °C, then −40 → +25 °C and 2 h/reflux; (d) Et 2 Zn/CH 2 Cl 2 /−20 °C, then add CH 2 I 2 /−20 °C/1 h then −20 → +25 °C/48 h, then 10% HCl in MeOH/25 °C/14 h; (e) 0.2 M PDC/DMF/25 °C/6 h; (f) CH 2 N 2 /Et 2 O. …”
The formation of methylenecyclopropanes by enzymatic desaturation of 11-cyclopropylundecanoic acid (1) and its disubstituted derivatives cis- and trans-3-5 has been investigated using the Delta(11) desaturase of Spodoptera littoralis as model enzyme. Gas chromatography coupled to mass spectrometry analyses of methanolyzed lipidic extracts from tissues incubated with each probe revealed that all the cyclopropyl fatty acids were transformed into the corresponding 11-cyclopropylidene acids, except for compound trans-5 (5b), which was not desaturated at C11. The formation of methylenecyclopropane 9 as the only reaction product from 1 indicates that a potential radical intermediate is too short-lived to allow rearrangement reactions. Information on the Delta(11) desaturase substrate binding domain is provided considering the cyclopropyl probes 3-5 as conformationally restricted analogues of the straight-chain substrates.
“…In spite of its interest for the preparation of valuable compounds, this fragmentation suppresses the possibility of obtaining 3 by the Wittig reaction of Scheme 1. However, 3 could also be prepared by a Wittig reaction between the ylid derived from iodide 13 and either the aldehyde 14 7 or 4formyl ethyl butonoate 15 8 . The iodide 13 was prepared starting from 9 by the sequence depicted in Scheme 6.…”
The synthesis of N-tosyl 2-aza [2,2,1] bicycloheptane substituted in 3-position by the α-chain of prostaglandins is described. This synthesis allowed the observation of two valuable transformations of the bicyclic framework: a ring expansion to a 2-aza [3,2,1] bicyclooctane derivative and a fragmentation to cis-1,3 disubstituted cyclopentyl amines.
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