556835-36-0Relevant academic research and scientific papers
Enantiospecific on-water bromination: A mild and efficient protocol for the preparation of alkyl bromides
Alletto, Francesco,Adamo, Mauro F. A.
supporting information, p. 8692 - 8698 (2020/12/29)
Herein we report the first example of an on-water enantiospecific synthesis of alkyl bromides. This procedure allowed the conversion of secondary activated alkyl sulphides to benzylic alkyl bromides, which were obtained in 80-99% yields. The reaction carried out on enantio-pure sulphides provided the corresponding bromides in high yields and enantioselectivity (up to 92% ee; 94% es) at room temperature. The on-water conditions reduced significantly the reaction times compared to similar procedures run in organic media. The condition identified made use of no solvent, required no temperature control and produced a smooth organic phase easily separated for further synthetic use on a multigram-scale without the need for any organic extraction. Therefore, the present constitutes the most operationally simple and environmentally benign approach to a class of much sought organic intermediates. This journal is
Sulphide as a leaving group: Highly stereoselective bromination of alkyl phenyl sulphides
Canestrari, Daniele,Cioffi, Caterina,Biancofiore, Ilaria,Lancianesi, Stefano,Ghisu, Lorenza,Ruether, Manuel,O'Brien, John,Adamo, Mauro F.A.,Ibrahim, Hasim
, p. 9042 - 9050 (2019/10/22)
A conceptionally novel nucleophilic substitution approach to synthetically important alkyl bromides is presented. Using molecular bromine (Br2), readily available secondary benzyl and tertiary alkyl phenyl sulphides are converted into the corresponding bromides under exceptionally mild, acid- and base-free reaction conditions. This simple transformation allows the isolation of elimination sensitive benzylic β-bromo carbonyl and nitrile compounds in mostly high yields and purities. Remarkably, protic functionalities such as acids and alcohols are tolerated. Enantioenriched benzylic β-sulphido esters, readily prepared by asymmetric sulpha-Michael addition, produce the corresponding inverted bromides with high stereoselectivities, approaching complete enantiospecificity at -40 °C. Significantly, the reported benzylic β-bromo esters can be stored without racemisation for prolonged periods at -20 °C. Their synthetic potential was demonstrated by the one-pot preparation of γ-azido alcohol (S)-5 in 90% ee. NMR studies revealed an initial formation of a sulphide bromine adduct, which in turn is in equilibrium with a postulated dibromosulphurane intermediate that undergoes C-Br bond formation.
N-heterocyclic carbene-catalyzed oxidation of aldehydes for the synthesis of amides via phenolic esters
Ji, Miran,Lim, Seungyeon,Jang, Hye-Young
, p. 28225 - 28228 (2014/07/22)
N-heterocyclic carbene-catalyzed oxidation using TEMPO is reported for the conversion of aldehydes to amides. A wide range of amides were synthesized in good yields (up to 72%) via a one-pot, sequential protocol involving oxidative esterification of aldehydes and subsequent aminolysis. To promote efficient aminolysis, various alkoxide leaving groups were evaluated.
Organocatalytic asymmetric sulfa-michael addition of thiols to α,β-unsaturated hexafluoroisopropyl esters: Expeditious access to (R)-thiazesim
Fang, Xin,Li, Jun,Wang, Chun-Jiang
supporting information, p. 3448 - 3451 (2013/07/26)
A highly efficient organocatalytic asymmetric SMA reaction of hexafluoroisopropyl α,β-unsaturated esters has been developed. Introducing electron-withdrawing hexafluoroisopropyl ester is crucial to enhancing the electrophilicity of unsaturated esters as S
Oxidative esterification of aldehydes using a recyclable oxoammonium salt
Kelly, Christopher B.,Mercadante, Michael A.,Wiles, Rebecca J.,Leadbeater, Nicholas E.
supporting information, p. 2222 - 2225 (2013/06/05)
A simple, high yielding, rapid route for the oxidative esterification of a wide range aldehydes to hexafluoroisopropyl (HFIP) esters using the oxoammonium salt 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (1a) is reported. These esters can be readily transformed into a variety of other functional groups. The spent oxidant (1b) can be recovered and conveniently reoxidized to regenerate the oxoammonium salt, 1a.
