Amidines as potent nucleophilic organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes
作者:Simon M. Ahmad、D. Christopher Braddock、Gemma Cansell、Stephen A. Hermitage、Joanna M. Redmond、Andrew J.P. White
DOI:10.1016/j.tetlet.2007.06.112
日期:2007.8
(+/-)-iso-Amarine is a potent organocatalyst at 1 mol% loading for both the bromoacetoxylation of alkenes with added acetic acid and bromolactonisation of unsaturated carboxylic acids with stoichiometric NBS as the electrophilic bromine source. A simple bromoamidine with an N-Br bond has been characterised crystallographically for the first time. Asymmetric induction in the bromination reactions with enantiopure amidines was zero. (c) 2007 Elsevier Ltd. All rights reserved.
Ortho-substituted iodobenzenes as novel organocatalysts for bromination of alkenes
作者:D. Christopher Braddock、Gemma Cansell、Stephen A. Hermitage
DOI:10.1039/b604130b
日期:——
Suitably ortho-substituted iodobenzenes act as organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes via the intermediacy of bromoiodinanes.
Catalytic asymmetric bromolactonization reactions using (DHQD)2PHAL-benzoic acid combinations
作者:Alan Armstrong、D. Christopher Braddock、Alexander X. Jones、Stacy Clark
DOI:10.1016/j.tetlet.2013.10.043
日期:2013.12
Catalytic (DHQD)2PHAL as modified by added benzoic acid, is an off-the-shelf catalyst-additive combination for effecting catalytic asymmetric bromolactonization reactions. This combination delivers bromolactones with asymmetric induction at a comparable level to bespoke catalysts previously optimized for particular substrate classes.
Study on the Bromolactonisation of Alkenoic Acids with (Diacetoxyiodo)Benzene
作者:Yan He、Zhenping Yang、Jie Yan
DOI:10.3184/030823410x12682297999384
日期:2010.3
A study on the bromolactonisation of alkenoic acids is reported. When various pent-4-enoic acids reacted with (diacetoxyiodo)benzene (DIB) and lithium bromide in CH3OH at room temperature, most of the five-membered bromolactones were obtained in good to excellent yields in short times. Some had two diastereoisomers. When but-3-enoic acid and trans-hex-3-enoic acid were treated under the same conditions
Dimethylformamide, dimethylacetamide and tetramethylguanidine as nucleophilic organocatalysts for the transfer of electrophilic bromine from N-bromosuccinimide to alkenes
作者:Simon M. Ahmad、D. Christopher Braddock、Gemma Cansell、Stephen A. Hermitage
DOI:10.1016/j.tetlet.2006.12.042
日期:2007.2
Dimethylformamide, dimethylacetamide and tetramethylguanidine were found to act as increasingly active catalysts for the bromolactonisation of gamma,delta- and delta,epsilon-unsaturated carboxylic acids with N-bromosuccinimide. The catalysts are readily removed in the work-up by washing with water to provide the pure bromolactone products without the need for column chromatography. Catalysis of the intermolecular bromoacetoxylation of alkenes with acetic acid and NBS by TMG was also demonstrated. (c) 2006 Elsevier Ltd. All rights reserved.