39082-44-5Relevant academic research and scientific papers
Base-free Enantioselective C(1)-Ammonium Enolate Catalysis Exploiting Aryloxides: A Synthetic and Mechanistic Study
McLaughlin, Calum,Slawin, Alexandra M. Z.,Smith, Andrew D.
, p. 15111 - 15119 (2019/11/05)
An isothiourea-catalyzed enantioselective Michael addition of aryl ester pronucleophiles to vinyl bis-sulfones via C(1)-ammonium enolate intermediates has been developed. This operationally simple method allows the base-free functionalization of aryl esters to form α-functionalized products containing two contiguous tertiary stereogenic centres in excellent yield and stereoselectivity (all ≥99:1 er). Key to the success of this methodology is the multifunctional role of the aryloxide, which operates as a leaving group, Br?nsted base, Br?nsted acid and Lewis base within the catalytic cycle. Comprehensive mechanistic studies, including variable time normalization analysis (VTNA) and isotopologue competition experiments, have been carried out. These studies have identified (i) orders of all reactants; (ii) a turnover-limiting Michael addition step, (iii) product inhibition, (iv) the catalyst resting state and (v) catalyst deactivation through protonation.
Stereoselective One-Pot Synthesis of cis-1,2-Dicyanoalkenes from 1,1-Bis(benzenesulfonyl)alkenes and KCN
Zhang, Yue,Wei, Yi,Li, Shen,Ma, Jun-An
supporting information, p. 199 - 203 (2019/01/04)
An efficient synthesis of cis-1,2-dicyanoalkenes by the reaction of 1,1-bis(benzenesulfonyl)alkenes with KCN was developed. This reaction was conducted in the presence of tetrabutylammonium bromide and NH4Cl/K3PO4 under phase-transfer conditions. A series of cis-1,2-dicyanoalkenes were obtained in good to high yields. Further transformation of the obtained product allows for access to imide and dicarboxylic acid compounds.
Enantioselective organocatalytic conjugate addition of aldehydes to vinyl sulfones and vinyl phosphonates as challenging michael acceptors
Sulzer-Mosse, Sarah,Alexakis, Alexandre,Mareda, Jiri,Bollot, Guillaume,Bernardinelli, Gerald,Filinchuk, Yaroslav
supporting information; experimental part, p. 3204 - 3220 (2009/12/03)
Chiral amines with a pyrrolidine framework catalyze the enantioselective conjugate addition of a broad range of aldehydes to various vinyl sulfones and vinyl phosphonates in high yields and with enantioselectivities up to >99% ee. This novel process provides synthetically useful chiral γ-gem-sulfonyl or phosphonyl aldehydes which can be widely functionalized with retention of the enantiomeric excess. Mechanistic insights including DFT calculations are explored in detail.
Highly enantioselective conjugate additions of aldehydes to vinyl sulfones
Landa, Aitor,Maestro, Miguel,Masdeu, Carme,Puente, Angel,Vera, Silvia,Oiarbide, Mikel,Palomo, Claudio
supporting information; experimental part, p. 1562 - 1565 (2009/10/01)
The use of less basic chiral amine catalysts for highly enantioselective conjugate additions of aldehydes to vinyl sulfones was reported. The results show that the addition of aldehydes to α-cyano vinyl sulfones takes place at -40°C to give alcohols. The
Alkyl- and arylsubstituted ketenedithioacetal tetroxides: Diels-Alder reactivity and reductive desulfonylation of the adducts
De Lucchi,Fabbri,Lucchini
, p. 1485 - 1496 (2007/10/02)
The Diels-Alder reactivity of the representative alkyl and aryl-substituted ketenedithioacetal tetroxides of general formula 1 is reported. These dienophiles reacted under thermal conditions (refluxing toluene) with cyclopentadiene to afford predominantly
Synthetic Studies on O-Heterocycles via Cycloadditions. Part 2. Adducts from Styrene Oxides
Clawson, Paul,Lunn, Patricia M.,Whiting, Donald A.
, p. 159 - 162 (2007/10/02)
The styrene oxides (14) and (15), bearing electron-withdrawing functions, readily undergo thermal and photochemical (triplet sensitised) dipolar cycloadditions with simple electron-deficient olefins, regioselectively in the case of methyl acrylate.However, cycloadditions with 5-arylbutenolides as dipolarophiles, required for lignan synthesis, could not be effected in significant yield.A new short route to 5-arylbut-2-enolides was devised.The dihydro- and tetrahydro-furan adducts (18d), (19d), and (20d) all fragment in base to the dienol nitrile (25).
