- Copper-Catalyzed Cross-Coupling Reaction of Allyl Boron Ester with 1°/2°/3°-Halogenated Alkanes
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The cross-coupling reaction of allyl boron ester with 1°/2°/3°-halogenated alkanes in the presence of copper has been developed for the first time, which provides a mild and efficient method for the construction of saturated C(sp3)-C(sp3) bonds. This protocol shows excellent compatibility with the nonactivated primary, secondary, and even tertiary halogenated alkanes under mild conditions.
- Wang, Guang-Zu,Jiang, Jian,Bu, Xiao-Song,Dai, Jian-Jun,Xu, Jun,Fu, Yao,Xu, Hua-Jian
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supporting information
p. 3682 - 3685
(2015/08/18)
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- Semivolatile and volatile compounds in combustion of polyethylene
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The evolution of semivolatile and volatile compounds in the combustion of polyethylene (PE) was studied at different operating conditions in a horizontal quartz reactor. Four combustion runs at 500 and 850°C with two different sample mass/air flow ratios and two pyrolytic runs at the same temperatures were carried out. Thermal behavior of different compounds was analyzed and the data obtained were compared with those of literature. It was observed that α,ω-olefins, α-olefins and n-paraffins were formed from the pyrolytic decomposition at low temperatures. On the other hand, oxygenated compounds such as aldehydes were also formed in the presence of oxygen. High yields were obtained of carbon oxides and light hydrocarbons, too. At high temperatures, the formation of polycyclic aromatic hydrocarbons (PAHs) took place. These compounds are harmful and their presence in the combustion processes is related with the evolution of pyrolytic puffs inside the combustion chamber with a poor mixture of semivolatile compounds evolved with oxygen. Altogether, the yields of more than 200 compounds were determined. The collection of the semivolatile compounds was carried out with XAD-2 adsorbent and were analyzed by GC-MS, whereas volatile compounds and gases were collected in a Tedlar bag and analyzed by GC with thermal conductivity and flame ionization detectors.
- Font, Rafael,Aracil, Ignacio,Fullana, Andrés,Conesa, Juan A.
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p. 615 - 627
(2007/10/03)
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- Synthesis of naturally occurring pyridine alkaloids via palladium-catalyzed coupling/migration chemistry
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The palladium-catalyzed cross-coupling of 3-iodopyridine, long-chain terminal dienes, and benzylic amines or tosylamides provides a novel route to key intermediates for the synthesis of the naturally occurring, biologically active pyridine alkaloids theonelladins C and D, niphatesine C, and xestamine D. This process involves (1) oxidative addition of the heterocyclic iodide to Pd(0), (2) carbopalladation of the least hindered carbon-carbon double bond of the diene, (3) palladium migration, and (4) π-allylpalladium displacement by the nitrogen nucleophile with simultaneous regeneration of the Pd catalyst. Subsequent hydrogenation and deprotection affords good yields of the natural products. The Pd-catalyzed coupling of 3-iodopyridine and 2-methyl-11-dodecen-1-ol provides a convenient synthesis of a long-chain aldehyde by an analogous palladium migration process, which is easily converted to the pyridine alkaloid ikimine A.
- Wang, Yao,Dong, Xiaoyang,Larock, Richard C.
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p. 3090 - 3098
(2007/10/03)
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- Hydrolytic kinetic resolution of terminal mono- and bis-epoxides in the synthesis of insect pheromones
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Hydrolytic kinetic resolution (HKR) of functionalised epoxides using (salen)Co(OAc) complexes provides enantiomerically enriched epoxides and diols, which have been transformed into important insect sex pheromones. In this general approach, (-)-(R)- and (+)-(S)-10-methyldodecyl acetates from the smaller tea tortrix moth were obtained, as was (-)-(R)-10-methyltridecan-2-one from the southern corn rootworm. The (S)-epoxide obtained from undec-1-en-6-yne was transformed to (-)-(R)-(Z)-undec-6-en-2-ol (Nostrenol) from ant-lions. HKR of appropriate bisepoxides was also investigated, and transformations of the resulting bisepoxides and epoxydiols provided (-)-(1R,7R)-1,7-dimethylnonylpropanoate from corn rootworms, (-)-(6R,12R)-6,12-dimethylpentadecan-2-one from the female banded cucumber beetle, and (-)-(2S,11S)-2,11-diacetoxytridecane and (+)-(2S,12S)-2,12-diacetoxytridecane from female pea-midges.
- Chow, Sharon,Kitching, William
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p. 779 - 793
(2007/10/03)
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- Synthesis of pyridine alkaloids via Pd-catalyzed coupling of 3-iodopyridine, 1,ω-dienes and nitrogen nucleophiles
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The palladium-catalyzed cross coupling of 3-iodopyridine, long chain 1,ω-dienes, and benzylic amines or tosylamides provides a novel route to key intermediates for the synthesis of the naturally occurring, biologically active pyridine alkaloids theonellad
- Larock, Richard C,Wang, Yao
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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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