61907-84-4Relevant academic research and scientific papers
Synthesis of N?H Bearing Imidazolidinones and Dihydroimidazolones Using Aza-Heck Cyclizations
Xu, Feiyang,Shuler, Scott A.,Watson, Donald A.
supporting information, p. 12081 - 12085 (2018/09/11)
The synthesis of unsaturated, unprotected imidazolidinones via an aza-Heck reaction is described. This palladium-catalyzed process allows for the cyclization of N-phenoxy ureas onto pendant alkenes. The reaction has broad functional group tolerance, can b
Transition Metal Free Cycloamination of Prenyl Carbamates and Ureas Promoted by Aryldiazonium Salts
Abrams, Roman,Lefebvre, Quentin,Clayden, Jonathan
supporting information, p. 13587 - 13591 (2018/09/25)
Upon treatment with aryldiazonium salts, prenyl carbamates and ureas undergo redox-neutral azocycloamination. In general, N-aryl O-prenyl carbamates cyclize in a photocatalytic reaction with visible light and an organic dye. With electron-deficient diazonium salts, electronic matching with an electron-rich N-aryl substituent results in a reaction proceeding in the ground state, without either light or photocatalyst. Cyclic voltammetry suggests that this radical reaction is initiated by hydrogen-atom abstraction mediated by an aryl radical, followed by a radical addition cascade and proton-coupled hole propagation. The reaction proceeds at room temperature in short reaction times, and a range of functional groups is tolerated.
Achieving control over the branched/linear selectivity in palladium-catalyzed allylic amination
Dubovyk, Igor,Watson, Iain D. G.,Yudin, Andrei K.
, p. 1559 - 1575 (2013/03/28)
Palladium-catalyzed reaction of unsymmetrical allylic electrophiles with amines gives rise to regioisomeric allylic amines. We have found that linear products result from the thermodynamically controlled isomerization of the initially formed branched products. The isomerization is promoted by protic acid and active palladium catalyst. The use of base shuts down the isomerization pathway and allows for the preparation and isolation of branched allylic amines. Solvent plays a key role in achieving high kinetic regioselectivity and in controlling the rate of isomerization. The isomerization can be combined with ring-closing metathesis to afford the synthesis of exocyclic allylic amines from their endocyclic precursors.
Development of an intramolecular aryne ene reaction and application to the formal synthesis of (±)-crinine
Candito, David A.,Dobrovolsky, Dennis,Lautens, Mark
, p. 15572 - 15580 (2012/11/07)
A general and high yielding annulation strategy for the synthesis of various carbo- and heterocycles, based on an intramolecular aryne ene reaction is described. It was found that the geometry of the olefin is crucial to the success of the reaction, with exclusive migration of the trans-allylic-H taking place. Furthermore, the electronic nature of the aryne was found to be important to the success of the reaction. Deuterium labeling studies and DFT calculations provided insight into the reaction mechanism. The data suggests a concerted asynchronous transition state, resembling a nucleophilic attack on the aryne. This strategy was successfully applied to the formal synthesis of the ethanophenanthridine alkaloid (±)-crinine.
Heavier alkaline earth catalysts for the intermolecular hydroamination of vinylarenes, dienes, and alkynes
Brinkmann, Christine,Barrett, Anthony G. M.,Hill, Michael S.,Procopiou, Panayiotis A.
supporting information; experimental part, p. 2193 - 2207 (2012/03/10)
The heavier group 2 complexes [M{N(SiMe3)2} 2]2(1, M = Ca; 2, M = Sr) and [M{CH(SiMe3) 2}2(THF)2] (3, M = Ca; 4, M = Sr) are shown to be effective precatalysts for the intermolecular hydroamination of vinyl arenes and dienes under mild conditions. Initial studies revealed that the amide precatalysts, 1 and 2, while compromised in terms of absolute activity by a tendency toward transaminative behavior, offer greater stability toward polymerization/oligomerization side reactions. In every case the strontium species, 2 and 4, were found to outperform their calcium congeners. Reactions of piperidine with para-substituted styrenes are indicative of rate-determining alkene insertion in the catalytic cycle while the ease of addition of secondary cyclic amines was found to be dependent on ring size and reasoned to be a consequence of varying amine nucleophilicity. Hydroamination of conjugated dienes yielded isomeric products via η3-allyl intermediates and their relative distributions were explained through stereoelectronic considerations. The ability to carry out the hydroamination of internal alkynes was found to be dramatically dependent upon the identity of the alkyne substituents while reactions employing terminal alkynes resulted in the precipitation of insoluble and unreactive group 2 acetylides. The rate law for styrene hydroamination with piperidine catalyzed by [Sr{N(SiMe3) 2}2]2 was deduced to be first order in [amine] and [alkene] and second order in [catalyst], while large kinetic isotope effects and group 2 element-dependent ΔS? values implicated the formation of an amine-assisted rate-determining alkene insertion transition state in which there is a considerable entropic advantage associated with use of the larger strontium center.
A detailed investigation of the aza-prins reaction
Dobbs, Adrian P.,Guesne, Sebastien J. J.,Parker, Robert J.,Skidmore, John,Stephenson, Richard A.,Hursthouse, Mike B.
scheme or table, p. 1064 - 1080 (2010/06/13)
The development of a Lewis acid-promoted aza-Prins reaction to form piperidines and pyrrolidines is described. Indium trichloride has been found to be a highly successful and mild Lewis acid for promoting this reaction. A thorough mechanistic investigation is described, including the factors that influence the formation of the 5- or 6-membered ring product(s). The Royal Society of Chemistry.
Tandem wittig - Ene reaction approach to kainic acid
Majik, Mahesh S.,Parameswaran, Peruninakulath S.,Tilve, Santosh G.
experimental part, p. 3591 - 3594 (2009/09/05)
The first example of a tandem Wittig - intramolecular ene reaction approach and its application toward the synthesis of kainic acid is reported. The synthetic pathway involves conversion of prenyl bromide into phosphorane 3, followed by one-pot Wittig ole
Chasing the proton culprit from palladium-catalyzed allylic amination
Dubovyk, Igor,Watson, Iain D. G.,Yudin, Andrei K.
, p. 14172 - 14173 (2008/09/18)
We have found that the addition of base has a significant effect on palladium-catalyzed allylic amination. The long-standing problem of controlling the branched-to-linear ratio has been solved. In the presence of DBU and inexpensive, readily available ligands, palladium-catalyzed allylation proceeds under kinetic control, leading to high branched selectivity. Given the widespread utility of palladium-catalyzed allylic amination, we expect that these findings will be relevant in many areas ranging from asymmetric catalysis to target-oriented synthesis. Copyright
Palladium/BINAP(S)-catalyzed asymmetric allylic amination
Faller,Wilt, Jeremy C.
, p. 633 - 636 (2007/10/03)
(Chemical Equation Presented) The enantioselective allylic amination of acyclic allylic carbonates catalyzed by a palladium/(S)-BINAP(S) system was investigated. Amination of several substrates proceeded with high ee. Crotyl carbonates show an unusually high regioselectivity for the branched isomer. The use of (S)-TolBINAP(S) and (S)-3,5-xylyl-BINAP(S) as ligands was found to increase the enantioselectivity of the aminations. A P,S binding mode of the BINAP(S) ligand was found in an X-ray crystallographic study.
New phenylselanyl group activation: Synthesis of aziridines and oxazolidin-2-ones
Miniejew, Catherine,Outurquin, Francis,Pannecoucke, Xavier
, p. 1575 - 1576 (2007/10/03)
After the study of different phenylselanyl group activators, halogenation by N-bromosuccinimide (NBS) has been shown to be the most suitable manner for cyclizing β-phenylselanyl amines into aziridines and also enabled production of oxazolidin-2-ones from N-Boc β-phenylselanyl amines in excellent yield.
