- Ruthenium-catalysed synthesis of chiral exocyclic allylic alcoholsviachemoselective transfer hydrogenation of 2-arylidene cycloalkanones
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An exclusive asymmetric reduction of C=O bonds of 2-arylidene four-, five-, six-, and seven-membered cycloalkanones has been studied systematically. The asymmetric transfer hydrogenation was performed using a robust and commercially available chiral diamine-derived ruthenium complex as a catalyst and HCOOH/Et3N as a hydrogen source under mild conditions, giving 51 examples of chiral exocyclic allylic alcohols in up to 96% yield and 99% ee. This method was also applicable to the gram-scale synthesis of the active intermediates of the anti-inflammatory loxoprofen and natural product (?)-goniomitine.
- Zhang, Kaili,Liu, Qixing,He, Renke,Chen, Danyi,Deng, Zhangshuang,Huang, Nianyu,Zhou, Haifeng
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supporting information
p. 1628 - 1632
(2021/03/09)
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- Rh(I)-catalyzed ring-opening of cyclobutanols via C–C bond activation: Synthesis of cis-olefin with a remote aldehyde
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A Rh(I)-catalyzed ring-opening of cyclobutanols has been developed with ring opening products bearing cis-olefin and a remote aldehyde. Various substrates bearing different substituted aryl groups, heterocyclic groups and alkyl groups were compatible with
- Nie, Yu,Chen, Jianzhong,Zhang, Wanbin
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supporting information
(2019/09/03)
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- Enantioselective route to ketones and lactones from exocyclic allylic alcohols via metal and enzyme catalysis
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A general and efficient route for the synthesis of enantiomerically pure α-substituted ketones and the corresponding lactones has been developed. Ruthenium- and enzyme-catalyzed dynamic kinetic resolution (DKR) with a subsequent Cu-catalyzed α-allylic substitution are the key steps of the route. The α-substituted ketones were obtained in high yields and with excellent enantiomeric excess. The methodology was applied to the synthesis of a naturally occurring caprolactone, (R)-10-methyl-6-undecanolide, via a subsequent Baeyer-Villiger oxidation.
- Warner, Madeleine C.,Nagendiran, Anuja,Bogár, Krisztián,B?ckvall, Jan-E.
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supporting information
p. 5094 - 5097
(2013/01/15)
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- Preparation of polycyclic systems by sequential 5-exo-digonal radical cyclization, 1,5-hydrogen transfer from silicon, and 5-endo-trigonal cyclization
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Radicals of type 1 undergo 5-exo diagonal cyclization, and the resulting vinyl radical abstracts hydrogen from silicon to afford a silicon-centered radical. This radical closes in a 5-endo trigonal manner to generate radicals of type 4, which are reduced
- Clive,Yang,Macdonald,Wang,Cantin
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p. 1966 - 1983
(2007/10/03)
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- Stereoselective hydrogen transfer reactions of vinyl radicals: Cyclization of alkynyl iodides by unimolecular chain transfer from silicon hydrides
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The cyclization of several substituted hexynyl and heptynyl iodides proceeds stereoselectively to give either E- or Z-exocyclic double bonds depending on the type of precursor and radical chain used, In UniMolecular Chain Transfer (UMCT) reactions, the intramolecular abstraction of hydrogen by the intermediate vinyl radical leads exclusively to the E-isomer while the traditional tin hydride method usually provides the Z-isomer with good selectivity.
- Martinez-Grau, Angeles,Curran, Dennis P.
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p. 5679 - 5698
(2007/10/03)
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- Baker's yeast reduction of arylidenecycloalkanones
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The baker's yeast reduction of arylidene cycloalkanones 5, 6 and 7 occurs initially through the catalysis of different enzymes to give the saturation of the double bond leading to the saturated ketones 9, 15 and 22 and the carbonyl reduction to the (S) allylic alcohols 8a, 14 and 23, possessing 0.99, 0.85 and 0.66 ee, respectively. The latter act as inhibitors for the carbonyl reducing enzyme thus preventing the further reduction of the saturated ketone. These compounds in the absence of allylic alcohols are further reduced to a mixture of diastereomic saturated (S) alcohols of high-moderate enantiomeric purity. Reduction experiments in D2O indicate that saturation of the double bond of 5 occurs by β re face addition of hydrogen, as shown by the obtainment of 10'.
- Fogliato, Giovanni,Fronza, Giovanni,Fuganti, Claudio,Lanati, Simonetta,Rallo, Roberta,Rigoni, Romina,Servi, Stefano
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p. 10231 - 10240
(2007/10/02)
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- Intramolecular reductive cyclization of aldehydes and ketones with alkynes promoted by samarium(II) iodide
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Samarium(II) iodide mediated intramolecular reductive coupling of carbonyl groups and alkynes in the presence of HMPA and t-BuOH was successfully performed to provide cyclized products. Some cyclic compounds containing a heteroatom such as oxygen or nitrogen were also efficiently prepared by this coupling reaction.
- Shim,Hwang,Kang,Chang
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p. 4765 - 4768
(2007/10/02)
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- Stereoselective Epoxidation of 3-trans-Benzylideneisoborneol
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2-Benzylidenecyclopentanol (2) can be epoxidized stereoselectively to furnish 2-trans-benzylidene-1β-hydroxycylopentane β-oxide (4) with either t-butyl hydroperoxide in the presence of vanadium catalyst or m-chloroperoxybenzoic acid.Epoxidation of 3-trans
- Sanghvi, Y. S.,Rao, A. S.
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p. 317 - 320
(2007/10/02)
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