- Cascade bio-hydroxylation and dehalogenation for one-pot enantioselective synthesis of optically active β-halohydrins from halohydrocarbons
-
A stereoselective hydroxylation and enantioselective dehalogenation cascade reaction was developed for the synthesis of optically active β-haloalcohols from halohydrocarbons. This cascade system employed P450 and halohydrin dehalogenase as two compatible biocatalysts, allowing a straightforward, greener and efficient access to β-halohydrins with excellent enantioselectivities (98-99%).
- Cui, Hai-Bo,Xie, Ling-Zhi,Wan, Nan-Wei,He, Qing,Li, Zhi,Chen, Yong-Zheng
-
supporting information
p. 4324 - 4328
(2019/08/21)
-
- Scalable anti-Markovnikov hydrobromination of aliphatic and aromatic olefins
-
To improve access to a key synthetic intermediate we targeted a direct hydrobromination-Negishi route. Unsurprisingly, the anti-Markovnikov addition of HBr to estragole in the presence of AIBN proved successful. However, even in the absence of an added initiator, anti-Markovnikov addition was observed. Re-examination of early reports revealed that selective Markovnikov addition, often simply termed "normal" addition, is not always observed with HBr unless air is excluded, leading to the rediscovery of a reproducible and scalable initiator-free protocol.
- Galli, Marzia,Fletcher, Catherine J.,Del Pozo, Marc,Goldup, Stephen M.
-
supporting information
p. 5622 - 5626
(2016/07/06)
-
- Enantioselective epoxidation of nonconjugated cis-olefins by chiral dioxirane
-
A variety of nonconjugated cis-olefins has been enantioselectively epoxidized with chiral ketones 2, and up to 92% ee has been obtained. The two prochiral faces of an olefin are likely stereodifferentiated by the relative hydrophobicity of the olefin substituents and/or allylic oxygen functionality.
- Burke, Christopher P.,Shi, Yian
-
supporting information; experimental part
p. 5150 - 5153
(2009/12/28)
-
- 2-CYANOPYRROLOPYRIMIDINES AND PHARMACEUTICAL USES THEREOF
-
The invention relates to pyrrolo pyrimidines of formula (I), wherein Y represents -(CH2)t-O- or -(CH2)r-S-, p is 1 or 2, r is 1, 2 or 3, t is 1, 2 or 3, or Y is -(CH2)j- or -CH=CH-, j is 1 or 2; p is 1 or 2, or Y is -(CH2)f-, f is 1 or 2, p is 1, and the further radicals and symbols have the meaning as defined herein; their preparation, their use as pharmaceuticals, pharmaceutical compositions containing them, the use of such a compound for the manufacture of a pharmaceutical preparation for the treatment of neuropathic pain and to a method for the treatment of such a disease in animals, especially in humans.
- -
-
Page/Page column 36
(2010/02/08)
-
- Thermodynamic Stabilities of Phenonium Ions Based on Bromide-Transfer Equilibria in the Gas Phase
-
The thermodynamic stabilities of the phenonium (ethylenebenzenium) ion and ring-substituted derivatives were determined based on the bromide-transfer equilibria in the gas phase. It has been shown that the phenonium ion is 2.4 kcal mol-1 more stable than the t-butyl cation, and that the substituent effect on its stability can be correlated with the Yukawa-Tsuno equation with a ρ value of -12.6 and an r+ of 0.62. An r+ value smaller than unity of the α-cumyl(1-methyl-1-phenylethyl) cation suggested that π-delocalization in the phenonium ion is essentially less effective than through a benzylic π-interaction. On the other hand, the ρ value of -12.6 is distinctly larger than that for the ordinary benzylic carbocation systems, but is comparable to that of the benzenium ion. In addition, it has been found that the r+ value of the phenonium ions in the gas phase is in complete agreement with that for the aryl-assisted process in the acetolysis of 2-arylethyl toluenesulfonates. This suggests that the degree of π-delocalization of the positive charge is the same in the transition state and the intermediate cation. It is concluded that an r+ value of 0.6, which is ranked at a unique position in the continuous spectrum of the resonance demand, is characteristic of the bridged structure of the phenonium ion intermediate and the transition state.
- Mustanir,Mishima, Masaaki,Fujio, Mizue,Tsuno, Yuho
-
p. 1401 - 1407
(2007/10/03)
-
- Stereochemical control in microbial reduction. Part 31: Reduction of alkyl 2-oxo-4-arylbutyrates by baker's yeast under selected reaction conditions
-
Treatment of baker's yeast with phenacyl chloride in an aqueous-organic solvent has been proven to be an effective method of inhibiting the enzymes that afford (S)-enantiomers of α-hydroxy esters in the reduction of α-keto esters. The procedure is effective for the whole-cell system to produce the (R)-product with high chemical yield and high enantiomeric excess.
- Dao, Duc Hai,Okamura, Mutsuo,Akasaka, Takeshi,Kawai, Yasushi,Hida, Kouichi,Ohno, Atsuyoshi
-
p. 2725 - 2737
(2007/10/03)
-
- Mechanism of the Formation of Herbertene from trans-Didehydrobicyclofarnesol
-
Product and (13)C labelling studies of the rearrangement of trans-didehydrobicyclofarnesol (+)-(1) to partly racemised herbertene have led us to propose a mechanism for the reaction.
- Frater, Georg,Mueller, Urs
-
p. 1198 - 1200
(2007/10/02)
-
- Substituent Effects on the Intramolecular Photochemical Reactions of Phenyl-Ethenyl Non-conjugated Bichromophoric Systems
-
The effects of substitution on the photochemistry of phenyl-ethenyl bichromophoric systems are reported.Methyl substitution at the 2-, 3-, 5-, and 1,1,2-positions in the pentene moiety of 5-phenylpent-1-ene reduces both reaction efficiency and selectivity but in contrast to intramolecular analogues the photoreaction of 3-phenethylcyclohexene is comparable with that of the corresponding cyclopentene.Incorporation of ester units in the connecting unit between the chromophores or on the ethene inhibits intramolecular cyclisation as does the presence of para OMe, CN, or COMe groups in 5-phenylpent-1-ene.In contrast reaction selectivity and efficiency are greatly promoted by ortho Me or OMe groups and the products reflect exlusive 1,3-cycloaddition.The presence of a para Me group in 5-phenylpent-1-ene leads to specific 2,6-intramolecular cyclisation but the reaction of the meta-Me derivative leads to four products derived from 1,3- and 1,5-intramolecular cycloaddition.The observations are discussed in terms of mechanisms of arene-ethene photoreactions and preferred conformations of the bichromophores.
- Ellis-Davies, Graham C. R.,Gilbert, Andrew,Heath, Peter,Lane, Jon C.,Warrington, John V.,Westover, David L.
-
p. 1833 - 1842
(2007/10/02)
-
- 9-(Arylalkyl or aroylalkyl)-1-oxa-4,9-diazaspiro(5.5)undecan-3-ones
-
Compounds useful in the prevention and/or treatment of hypertension, congestive heart failure, arrhythmia, migraine, vasospastic disorders, and asthma are represented by the formula STR1 wherein: R1 is STR2 wherein X is hydrogen, lower alkyl, lower alkoxy, halo, carboxamido or hydroxy; m is 1, 2 or 3; and n is 1, 2 or 3; R2, R3 and R4 are independently hydrogen or lower alkyl; and the pharmaceutically acceptable acid addition salts thereof.
- -
-
-