6308-96-9Relevant articles and documents
Electrophilic Bromination of Micelle-Associated Alkenes as a Probe of Micelle Structure
Lennox, R. Bruce,McClelland, Robert A.
, p. 3771 - 3781 (1986)
The products and kinetics have been examined for the bromination in aqueous micelles of a series of unsaturated fatty acids, esters, and alcohols.A limited kinetic study of mercuration in SDS micelles is also reported.Bromination products are the following: CTAB micelles, 100percent dibromide; CTAC, principally α-bromochloride, with some bromohydrin and trace dibromide; SDS, a 2:1 mixture of bromohydrin and a bromosulfate ester derived from reaction with the headgroup of the micelle.These products are formed stereospecifically anti,and there is no significant dependence on the original position or geometry of the double bond.The bromination kinetic studies, carried out in SDS, Brij-35, and CTAB micelles, reveal considerably slower rates as compared to those in water and, in contrast to homogeneous media, sensitivities to the double bond position, its geometry and the presence of other unsuturated chains, and an enhanced terminal alkene reactivity.A dependency on micelle charge type and added salts is also observed.Both products and kinetics support a mechanism where the bromonium ion intermediate is formed and trapped in a relatively polar region of the micelle, intimately associated with the headgroup and its counterions.A model, the segment protrusion model, is proposed in which the double bond enters the "reactive" region by protrusion of a chain segment from the relatively nonpolar hydrocarbon region.The rate of reaction is determined by the absolute rate in this region, which is large, offset by the probability of the double bond being found there, which is small.The fraction of double bonds in a reactive state is determined by two factors: the probability that the chain segment containing the double bond will reach an interfacial location and the free energy cost of solubilizing a chain segment in a polar environment.This model is examined in the context of other recent experimentally and theoretically based models of micelles.
Preparation of a novel bromine complex and its application in organic synthesis
Nishio, Yuya,Yubata, Kotaro,Wakai, Yutaro,Notsu, Kotaro,Yamamoto, Katsumi,Fujiwara, Hideki,Matsubara, Hiroshi
, p. 1398 - 1405 (2019/02/07)
Although molecular bromine (Br2) is a useful brominating reagent, it is not easy to handle. Herein, we describe the preparation of a novel air-stable bromine complex prepared from 1,3-dimethyl-2-imidazolidinone (DMI) and Br2, which was identified to be (DMI)2HBr3 by spectral and X-ray techniques. This complex was then used to brominate olefins, carbonyl compounds, and aromatics, as well as in the Hofmann rearrangement. Yields of reaction products using this complex were almost the same or superior to those using other bromine alternatives.
Configurational Assignment of ‘Cryptochiral’ 10-Hydroxystearic Acid Through an Asymmetric Catalytic Synthesis
Brunner, Andreas,Hintermann, Lukas
, p. 928 - 943 (2016/12/09)
An asymmetric catalytic total synthesis of (S)-10-hydroxystearic acid (1) for comparison of its absolute configuration to that of samples obtained by fermentative hydration of oleic acid is reported. The synthesis involves two catalytic key-steps, namely Ru-catalyzed anti-Markovnikov hydration of 9-decynoic acid (7) to 10-oxodecanoic acid (5), followed by titanium-mediated asymmetric catalytic addition of dioctylzinc (25) to 5 in presence of the chiral ligand N,N’-((1R,2R)-cyclohexane-1,2-diyl)bis(1,1,1-trifluoromethanesulfonamide) (6). The synthesis is short and efficient and avoids use of protecting groups. Ozonolysis of 10-undecynoic acid (9) to 5 provides an alternative entry point into the synthetic route. The double dehydrobromination of (ω,ω-1)-dibromoalkanoic acids to ω-alkynoic acids under a variety of conditions was investigated with 10,11-dibromoundecanoic acid (11) as model substrate and using qNMR to quantify all reaction products. The synthetic approaches presented here have the potential to be generalized to the asymmetric catalytic synthesis of a variety of n-hydroxy-fatty acids.
