- Concise syntheses of (7Z,11Z,13E)-hexadecatrienal and (8E,18Z)- tetradecadienal
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Concise and efficient syntheses of (7Z,11Z,13E)-hexadecatrienal, a sex-pheromone component of the citrus leaf miner, and (8E,10Z)-tetradecadienal, the sex pheromone of the horse-chestnut leaf miner were described, starting from the commercially available acetylene and acrolein. The stereoselective formation of E,Z-conjugated double bond relied on cross-coupling between Grignard reagent and (E,Z)-bromodiene. The present syntheses achieved high overall yield (26% of the former and 23% for the latter) and high isomeric purity (97% for the former and 99% for the latter). Georg Thieme Verlag Stuttgart · New York.
- Ma, Zengxiao,Yang, Xiaomei,Zhang, Yushun,Huang, Xiangzhong,Tao, Yunhai
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scheme or table
p. 581 - 584
(2012/04/11)
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- Syntheses and palladium, platinum, and borane adducts of symmetrical trialkylphosphines with three terminal vinyl groups, P((CH2) mCH=CH2)3
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Reactions of Br(CH2)mCH=CH2 with Mg powder and then PCl3 (0.33 equiv.) afford P((CH2)m-CH=CH 2)3 (1; m = a, 4; b, 5; c, 6; d, 7; e, 8; f, 9; 52-87 %). Reactions of 1a-c, e with PdX2(COD) (X = Cl, Br) give trans-PdX 2(P((CH2)mCH=CH2)3) 2 (35-92 %). Reactions of 1b-e with PtCl2 in benzene give mainly trans-PtCl2(P((CH2)mCH=CH 2)3)2 (trans-5b-e; 52-75 %), whereas those with K2PtCl4 in water give mainly cis-5b-e (33-70 %). The reaction of equimolar quantities of 1c and H3B.S(CH3) 2 gives the 1 : 1 adduct H3B·P((CH 2)6CH=CH2)3 (85 %). In none of these transformations are by-products derived from the C=C linkages observed.
- Nawara-Hultzsch, Agnieszka J.,Skopek, Katrin,Shima, Takanori,Barbasiewicz, Micha,Hess, Gisela D.,Skaper, Dirk,Gladysz, John A.
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body text
p. 414 - 424
(2010/10/01)
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- Efficient synthesis of (S)-2-(cyclopentyloxycarbonyl)-amino-8-nonenoic acid: Key building block for BILN 2061, an HCV NS3 protease inhibitor
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A new procedure for the practical synthesis of (S)-2-(cyclopen- tyloxycarbonyl)amino-8-nonenoic acid, a key building block for BILN 2061, an HCV NS3 protease inhibitor, has been developed. The key step features a kinetic resolution of racemic 2-acetylamino-8-nonenoic acid with acylase I. In addition, the undesired (R)-2-acetylamino-8-nonenoic acid was recycled after racemization. The procedure was implemented for the production of (S)-2-(cyclopentyloxycarbonyl)amino-8-nonenoic acid on pilot-plant scale.
- Wang, Xiao-Jun,Zhang, Li,Smith-Keenan, Lana L.,Houpis, Ioannis N.,Farina, Vittorio
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- Amido functionalized ansa half-sandwich dichloride complexes of titanium, zirconium and hafnium with alkyl and ω-alkenyl substituents as homogeneous and self-immobilizing catalyst precursors for ethylene polymerization
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A total of 24 amido functionalized ansa half-sandwich dichloride complexes of titanium, zirconium and hafnium with cyclopentadienyl or indenyl ligands have been prepared, characterized and used for catalytic ethylene polymerization. Alkyl and ω-alkenyl substituents on the aromatic system influence the polymerization activity of the catalysts and the properties of the produced polyethylene. After activation with methylalumoxane the ω-alkenyl substituted catalysts show self-immobilization in ethylene polymerization.
- Alt, Helmut G.,Reb, Alexander,Milius, Wolfgang,Weis, Annette
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p. 169 - 182
(2007/10/03)
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- Dilithium tetrachlorocuprate catalyzed coupling of allylmagnesium bromide with α,ω-dihaloalkanes
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Allylmagnesium bromide has been shown to cross-couple with α,ω- dihaloalkanes in the presence of dilithium tetrachlorocuprate to yield, depending on reaction conditions, mono-coupled haloalkenes or di-coupled alkadienes. The order of the reactivity of the dihalides is I > Br >> CI and secondary halides show greater reactivity than primary halides.
- Johnson,Donohoe,Kang
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p. 1557 - 1564
(2007/10/02)
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- INTRAMOLEKULARE CYCLOADDITIONEN MIT ISOBENZOFURANEN - III. EIN HYDRIERTES NAPHTHOTHIOPHEN AUS EINEM 1-ALKENYLTHIENOFURAN
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The synthesis of tetrahydronaphthothiophene 6 utilizing an intramolecular Diels-Alder reaction with an 1-alkenylthienofuran 4 is described.
- Schoening, A.,Friedrichsen, W.
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p. 1137 - 1138
(2007/10/02)
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- Synthesis of Various New Nitroxide Free Radical Fatty Acids
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A generally applicable method is presented for the synthesis of various new nitroxide fatty acid isomers in which the fatty acid chains are attached at different positions of the pyrrolidin-1-oxyl ring.These isomers can be obtained by Michael addition of a nitroalkane to an α,β-unsaturated ketone to give a γ-nitro ketone, followed by ring closure with zinc and ammonium chloride to give a 1-pyrroline N-oxide which then reacts with Grignard reagents to give a pyrrolidin-1-oxyl free radical compound, which undergoes phase transfer oxidation of its terminal unsaturated bond.
- Hideg, Kalman,Lex, Laszlo
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p. 1431 - 1438
(2007/10/02)
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