217795-79-4Relevant articles and documents
Interrupted Pyridine Hydrogenation: Asymmetric Synthesis of δ-Lactams
Wagener, Tobias,Lückemeier, Lukas,Daniliuc, Constantin G.,Glorius, Frank
, p. 6425 - 6429 (2021/02/22)
Metal-catalyzed hydrogenation is an effective method to transform readily available arenes into saturated motifs, however, current hydrogenation strategies are limited to the formation of C?H and N?H bonds. The stepwise addition of hydrogen yields reactive unsaturated intermediates that are rapidly reduced. In contrast, the interruption of complete hydrogenation by further functionalization of unsaturated intermediates offers great potential for increasing chemical complexity in a single reaction step. Overcoming the tenet of full reduction in arene hydrogenation has been seldom demonstrated. In this work we report the synthesis of sought-after, enantioenriched δ-lactams from oxazolidinone-substituted pyridines and water by an interrupted hydrogenation mechanism.
3-Acetoxyquinuclidine as Catalyst in Electron Donor-Acceptor Complex-Mediated Reactions Triggered by Visible Light
Bosque, Irene,Bach, Thorsten
, p. 9103 - 9109 (2019/10/16)
3-Acetoxyquinuclidine was found to act as a catalytic electron donor species in a variety of electron donor-acceptor complex-mediated reactions. Only substoichiometric amounts (10-25 mol %) were needed to trigger the desired reaction. The outcome could be tuned by selecting the nature of the formed radical to perform amino- and hydro-decarboxylation, dimerization, and cyclization reactions. Importantly, no external additives were needed in this reaction.
Aminolysis of benzyl 2-pyridyl thionocarbonate and t-butyl 2-pyridyl thionocarbonate: Effects of nonleaving groups on reactivity and reaction mechanism
Kim, Min-Young,Lee, Jae-In,Um, Ik-Hwan
, p. 1115 - 1119 (2013/07/28)
A kinetic study is reported for nucleophilic substitution reactions of benzyl 2-pyridyl thionocarbonate (5b) and t-butyl 2-pyridyl thionocarbonate (6b) with a series of alicyclic secondary amines in H2O at 25.0 °C. Generalbase catalysis, which has often been reported to occur for aminolysis of esters possessing a C=S electrophilic center, is absent for the reactions of 5b and 6b. The Bronsted-type plots for the reactions of 5b and 6b are linear with ssnuc = 0.29 and 0.43, respectively, indicating that the reactions of 5b proceed through a stepwise mechanism with formation of a zwitterionic tetrahedral intermediate (T±) being the rate-determining step while those of 6b proceed through a concerted mechanism. The reactivity of 5b and 6b is similar to that of their oxygen analogues (i.e., benzyl 2-pyridyl carbonate 5a and t-butyl 2-pyridyl carbonate 6a, respectively), indicating that the effect of modification of the electrophilic center from C=O to C=S (i.e., from 5a to 5b and from 6a to 6b) on reactivity is insignificant. In contrast, 6b is much less reactive than 5b, indicating that the replacement of the PhCH2 in 5b by the t-Bu in 6b results in a significant decrease in reactivity as well as a change in the reaction mechanism (i.e., from a stepwise mechanism to a concerted pathway). It has been concluded that the contrasting reactivity and reaction mechanism for the reactions of 5b and 6b are not due to the electronic effects of PhCH2 and t-Bu but are caused by the large steric hindrance exerted by the bulky t-Bu in 6b.
