RESUMEN
Three hybrid electrochemical protocols, which involve the energy transfer, direct photolysis and N-hydroxyphthalimide catalyst, respectively, are presented for the selenylation/cyclization of the fragile substrates of 3-aza-1,5-dienes with diorganyl diselenides to afford 3-selenomethyl-4-pyrrolin-2-ones. The two electrophotocatalytic reactions and the indirect electrolysis one are both regioselective and external-oxidant- and transition-metal-free, and are associated with a broad substrate scope and high Se-economy, and all three methods are amenable to gram-scale syntheses, late-stage functionalizations, sunlight-induced experiments and all-solar-driven syntheses.
RESUMEN
An electrochemical or photoelectrochemical regioselective polyfluoroalkylation/cyclization cascade of 3-aza-1,5-dienes with sodium fluoroalkanesulfinates is presented. This protocol proceeds with a broad substrate scope and good functional group tolerance under mild, oxidant-free, transition-metal-free, and electrolyte-free conditions to provide 3-polyfluoroalkylated 4-pyrrolin-2-ones in one step from readily available N-vinylacrylamides, and it is readily scalable to the Gram scale.
RESUMEN
A chemical reductant or a sacrificial electron donor is required in any reduction reactions, generally resulting in undesired chemical waste. Herein, we report a reductant-free reductive [3 + 2 + 1] annulation of ß-keto amides with CS2 enabled by the synergy of electro/copper/base using water as an innocuous anodic sacrifice with O2 as a sustainable by-product. This electrochemical protocol is mild and provides access to polyfunctionalized pyridin-2-ones from simple starting materials in a single step.
RESUMEN
A heat- or photoredox/iron dual catalysis-enabled dehydrogenative acylarylation of N-allyl anilines leading to 2-substituted 3-(α-acyl) indolines with a quaternary stereogenic center is presented, with unactivated alkenic bonds as radical acceptors and simple aldehydes as radical precursors. This reaction features high yields, a broad substrate scope, and a great exo selectivity, and gram-scale syntheses could be readily carried out.
RESUMEN
Styrene butadiene rubber latex (SBR), waterborne epoxy adhesive (WE) and colloidal silica sol (SiO2) were used to prepare modified bitumen emulsion for cold mix asphalt. The modification effects of the individual modifiers and the combination of these modifiers were investigated by using bonding strength and dynamic shear rheological property. Test results showed that the modifier dosage helped to balance the performance of modified bitumen emulsion by improving its bonding strength without compromising its rheological properties. The critical dosage at which the peak bonding strength occurred was 4%, 12% and 4% for SBR, WE and SiO2 respectively. Improved rheological performance on the master curves was well distinguished, in particular, by increased complex modulus and reduced phase angle at the low frequency region. Abrupt changes, especially on phase angle occurred when the modifier dosage was beyond 12%. The measured ratio between bonding strength and complex shear modulus could vary ranging from 10-2 to 102. Highly-modified bitumen emulsion with good adhesion, rheology and compatibility can be prepared by using the combination of SBR, WE and SiO2. It is important to carefully select the type and dosage of modifier for a particular combination to optimize the performance of modified bitumen emulsion.
RESUMEN
A rare example of C(sp3 )-H functionalization of simple alkanes with unactivated alkenes is presented. In the presence of a copper salt and di-tert-butyl peroxide (DTBP), N-allyl anilines underwent exo-selective alkylation/cyclization cascade with unactivated alkenic bonds as radical acceptors and simple alkanes as radical precursors, providing a direct access to 3-alkyl indolines. The present protocol features simple operation, broad substrate scope and great exo selectivity.
RESUMEN
An unprecedented benzylic C-H functionalization of methyl arenes across unactivated alkenes is presented. In the presence of MnCl2·4H2O and di- tert-butyl peroxide, N-allyl anilines underwent benzylation/cyclization cascade to give benzylated indolines, which are a previously unmet synthetic goal. This protocol features simple operation, broad substrate scope, and great exo selectivity.
RESUMEN
With an unactivated double bond as the radical acceptor, allyl amines underwent a metal-free trifluoromethylation/cyclization cascade with CF3SO2Na (Langlois' reagent), affording CF3CH2-containing indolines and tetrahydroisoquinolines, whose practical syntheses are significant challenges. This protocol features mild conditions, low cost, and a broad substrate scope.
RESUMEN
A silver-catalyzed phosphorylation/cyclization cascade of N-allyl anilines was developed, allowing direct access to 3-phosphonoalkyl indolines, which were previously obtainable only via tedious procedures under harsh/toxic conditions. The unactivated double bond serves as the radical acceptor, whereas H-phosphonates or -phosphine oxides act as the radical precursor. This protocol features simple operation, broad substrate scope, and great exo selectivity, and a gram-scale synthesis could be readily carried out.
