- Hydrofunctionalization of olefins to value-added chemicals: Via photocatalytic coupling
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A green strategy was developed for the synthesis of various value-added chemicals using methanol, acetonitrile, acetic acid, acetone and ethyl acetate as the hydrogen source by coupling them with olefins over heterogeneous photocatalysts. A radical coupling mechanism was proposed for the hydrofunctionalization of olefins with methanol to higher aliphatic alcohols over the Pt/TiO2 catalyst as the model reaction. C-H bond cleavage and C-C bond formation between photogenerated radicals and terminal olefins were accomplished in a single reaction at high efficiency. Our approach is atomically economical with high anti-Markovnikov regioselectivity and promising application potential under mild reaction conditions.
- Fan, Yonghui,Li, Shenggang,Bao, Jingxian,Shi, Lei,Yang, Yanzhang,Yu, Fei,Gao, Peng,Wang, Hui,Zhong, Liangshu,Sun, Yuhan
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supporting information
p. 3450 - 3456
(2018/08/06)
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- Syntheses of female sex pheromone precursors of pine sawfly species and of some structurally related methyl-branched long-chain 2-alkanols.
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3,7-Dimethyl-2-undecanol, 3,7,9-trimethyl-2-tridecanol, and 3,7, 11-trimethyl-2-tridecanol were synthesized as racemic mixtures in moderate yields. The alcohols are known precursors of the female sex pheromones of the pine sawfly species Diprion nipponica, Macrodiprion nemoralis, and Microdiprion pallipes, respectively. Stereoisomeric mixtures of 3,8,12-trimethyl-2-tridecanol, erythro-(2R,3R, 11R/S)-3,11-dimethyl-2-tetradecanol, 3,5-dimethyl-2-tetradecanol, and 5,7-dimethyl-2-tetradecanol, structurally related to sex pheromone alcohol precursors of pine sawfly species, were also synthesized in moderate yields. The key reaction in the syntheses was the ring opening of gamma-butyrolactones by using different alkyl lithiums as nucleophiles.
- Hedenstroem, Erik,Andersson, Fredrik
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p. 1237 - 1254
(2007/10/03)
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- Do enzymes recognise remotely located stereocentres? Highly enantioselective Candida rugosa lipase-catalysed esterification of the 2- to 8-methyldecanoic acids
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Several racemic methyl decanoic acids have been synthesised and successfully resolved in esterification with 1-hexadecanol at aw=0.8 in cyclohexane using immobilised Candida rugosa lipase (CRL) as the catalyst. The enantiomeric ratios (E=2.8-68) obtained were surprisingly high even when the methyl group was as remotely located as in 8-methyldecanoic acid (E=25). Interestingly, the lipase shows enantiopreference for the S-enantiomer when the methyl group is located on even numbered carbons i.e. for the 2-,4-,6- and 8-methyldecanoic acids and to the R-enantiomer when the methyl group is located on uneven numbered carbons i.e. for the 3-,5- and 7-methyldecanoic acids.
- Hedenstroem, Erik,Nguyen, Ba-Vu,Silks III, Louis A.
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p. 835 - 844
(2007/10/03)
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- Phosphine-directed stereo- and regioselective Ni-catalyzed reactions of Grignard reagents with allylic ethers
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Studies on the directed regio- and stereoselective Ni-catalyzed allylic substitution reactions involving methyl-and phenylmagnesium bromides and various acyclic and cyclic allylic ethers are reported. In the presence of a properly positioned internal Lewis base, C-C bonds can be formed catalytically and with excellent levels of selectivity. Internal chelation allows Ni-catalyzed C-C bond forming reactions that are otherwise non-selective, sluggish, or do not occur at all, to proceed to completion readily, in excellent yields, at ambient temperature and with high regio- and stereocontrol. Directed alkene isomerization highlights an especially attractive feature of the metal-catalyzed alkylation strategy: because the initial product contains a prostereogenic site that remains within reach of the internal Lewis base, it can be subjected to additional directed stereoselective manipulations.
- Didiuk, Mary T.,Morken, James P.,Hoveyda, Amir H.
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p. 1117 - 1130
(2007/10/03)
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- Application de la reaction de Guerbet a la methylation de n-alcanols primaires
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The Guerbet reaction is applied to the methylation of different primary n-alkanols.For 1-n-undecanol 1, selectivities of 70 to 80 percent in 2-methylation are obtained using an excess of methanol, sodium or sodium methoxide as bases and nickel or palladium as catalysts.These transformations which were extended to other primary n-alkanols are obtained at lower temperatures (160-200 deg C) than in the described hitherto conditions.Industrial applications of this Guerbet reaction could be of great interest in these simpler experimental conditions.
- Sabadie, Jean,Descotes, Gerard
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p. 253 - 256
(2007/10/02)
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