41616-59-5Relevant articles and documents
Acceptorless dehydrogenative construction of CN and CC bonds through catalytic aza-Wittig and Wittig reactions in the presence of an air-stable ruthenium pincer complex
Biswas, Nandita,Das, Kalicharan,Sardar, Bitan,Srimani, DIpankar
, p. 6501 - 6512 (2019/05/24)
The construction of CN bonds was achieved by the dehydrogenative coupling of alcohol and azide via aza-Wittig type reaction. The reaction is catalyzed by an acridine-derived ruthenium pincer complex and does not use any oxidant. The present protocol offers a wide substrate scope, including aliphatic, aryl or heteroaryl alcohol/azides. This expeditious protocol was successfully applied to construct a CC bond directly from alcohol via dehydrogenative Wittig reaction. Furthermore, the synthesis of structurally important pyrrolo[1,4]benzodiazepine derivatives was also achieved by this methodology.
Separation of Ring Polar and Resonance Effects on the Rate and Equilibrium Constants for Methoxide Ion-Promoted Addition of Methanol to N-Benzylideneanilines Substituted at the Benzylidene Moiety
Toullec, Jean,Bennour, Sadjia
, p. 2831 - 2839 (2007/10/02)
Rate and equilibrium constants for the title reaction (α-amino ether formation) at 25 deg C in methanol are reported for 16 N-benzylideneanilines (BAs) substituted at the benzaldehyde moiety.In contrast to a previous report dealing with BAs substituted at the aniline residue, it is shown that an uncatalyzed pathway competes with the methoxide ion-catalyzed reaction, these two processes corresponding to rate-limiting attachment of the lyate ion to the C=N bond of iminium ion and free imine, respectively.For the latter reaction pathway, the lifetimes of the amide-ion intermediates are long enough to allow a stepwise mechanism.The equilibrium constants for the overall reaction are correlated by the two-parameter Young-Jencks (YJ) equation n?n + ρr(?+ - ?n) + C> allowing separation of the overall polar effect of the substituted ring (ρn = 0.87), including resonance-induced polar (RP) effects, from the direct resonance (DR) effect due to conjugation with the C=N group (ρr = 0.54).For the forward methoxide ion-catalyzed process, the polar and DR contributions to the substituent effects on the second-order rate constant have the same sign (ρn = 1.79 and ρr = 0.28, respectively), but these have opposite signs (ρn = 0.92 and ρr = -0.25) for the reverse reaction.The contribution of the DR effects for the reverse rate constants, which make the points lie above the log k-?n line, stems from gain in resonance at the negatively charged transition state.The validity and significance of the YJ treatment are discussed.
