- Chemoenzymatic Synthesis of Substituted Azepanes by Sequential Biocatalytic Reduction and Organolithium-Mediated Rearrangement
-
Enantioenriched 2-aryl azepanes and 2-arylbenzazepines were generated biocatalytically by asymmetric reductive amination using imine reductases or by deracemization using monoamine oxidases. The amines were converted to the corresponding N′-aryl ureas, which rearranged on treatment with base with stereospecific transfer of the aryl substituent to the 2-position of the heterocycle via a configurationally stable benzyllithium intermediate. The products are previously inaccessible enantioenriched 2,2-disubstituted azepanes and benzazepines.
- Zawodny, Wojciech,Montgomery, Sarah L.,Marshall, James R.,Finnigan, James D.,Turner, Nicholas J.,Clayden, Jonathan
-
supporting information
p. 17872 - 17877
(2019/01/04)
-
- Highly effective asymmetric hydrogenation of cyclic N -alkyl imines with chiral cationic Ru-MsDPEN catalysts
-
A range of cyclic N-alkyl imines were efficiently hydrogenated by using a chiral cationic Ru(η6-cymene)(MsDPEN)(BArF) complex (MsDPEN = N-(methanesulfonyl)-1,2-diphenylethylenediamine) in high yields and up to 98% ee. A one-pot synthesis of chiral 2-phenylpyrrolidine via reductive amination was also developed.
- Chen, Fei,Ding, Ziyuan,Qin, Jie,Wang, Tianli,He, Yanmei,Fan, Qing-Hua
-
supporting information; experimental part
p. 4348 - 4351
(2011/10/13)
-
- The reaction of cyclic imines with the Ruppert-Prakash reagent. Facile approach to α-trifluoromethylated nornicotine, anabazine, and homoanabazine
-
We have demonstrated that the Ruppert-Prakash reagent is able to react with a number of cyclic imines under acidic condition to afford the corresponding α-trifluoromethyl derivatives of nitrogen heterocycles. 5-7-Membered cyclic imines bearing various alkyl, aryl or heterocyclic group were successfully involved in this transformation. Novel trifluoromethylated analogues of nicotine, anabasine, and homoanabasine alkaloids were synthesized.
- Shevchenko, Nikolay E.,Vlasov, Katja,Nenajdenko, Valentine G.,R?schenthaler, Gerd-Volker
-
scheme or table
p. 69 - 74
(2011/02/27)
-
- Synthesis of aminoalkylpyrazoles and-isoxazoles from cyclic β-(trifluoroacetyl) enamines
-
A method for the synthesis of cyclic β-(trifluoroacetyl) enamines was proposed. Reactions of the latter with hydrazine and hydroxylamine gave pyrazoles and isoxazoles, respectively, containing trifluoromethyl and ω-aminoalkyl fragments. Addition of hydraz
- Nenajdenko,Pronin,Balenkova
-
p. 336 - 344
(2008/03/11)
-
- Oxidative C-arylation of free (NH)-heterocycles via direct (sp3) C-H bond functionalization
-
The development of a new chemical transformation, namely oxidative C-arylation of saturated (NH)-heterocycles, is described. This reaction combines dehydrogenation and arylation in one process, leading to cross-coupling of (NH)-heterocycles and haloarenes. Typical reaction conditions involve heating the reaction partners in anhydrous dioxane at 120-150 °C in the presence of RhCl(CO)[P(Fur)3]2 as the catalyst and Cs2CO3 as the base. Addition of tert-butylethylene as the hydrogen acceptor increases the chemical yield by diminishing the dehalogenation pathway. This method demonstrated a good substrate scope, allowing for cross-coupling of a variety of (NH)-heterocycles (e.g., pyrrolidine, piperidine, piperazine, morpholine) and halo(hetero)arenes to afford valuable heterocyclic products in one step. The preliminary mechanistic studies provided some insight regarding the key events in the proposed catalytic cycle, including β-hydride elimination of an amido rhodium complex and carbometalation of the resulting imine. A large kinetic isotope effect [KIE (kC-H/kC-D) = 4.3] suggests that one or both β-hydride elimination steps are rate determining. The central role for the phosphine ligand was established in controlling the partitioning between the oxidative C-arylation and N-arylation pathways. Copyright
- Sezen, Bengue,Sames, Dalibor
-
p. 13244 - 13246
(2007/10/03)
-
- A One-Pot Process for the Enantioselective Synthesis of Amines via Reductive Amination under Transfer Hydrogenation Conditions
-
(Equation presented) Cyclic amines may be prepared via a sequence of deprotection followed by intramolecular reductive amination of t-Boc-protected amino ketones under asymmetric transfer hydrogenation conditions. In cases where the corresponding imine reaction proceeds with high enantioselectivity, this is reflected in the one-step process.
- Williams, Glynn D.,Pike, Richard A.,Wade, Charles E.,Wills, Martin
-
p. 4227 - 4230
(2007/10/03)
-
- Catalytic asymmetric hydrogenation of imines with a chiral titanocene catalyst: Scope and limitations
-
The asymmetric hydrogenation of imines with a chiral titanocene catalyst derived from Brintzinger's ansatitanocene complex 1 proceeds to afford amines with good to excellent enantioselectivity. The catalyst is particularly effective for the reduction of cyclic imines. For these substrates enantiomeric excesses from 95 to 99% were achieved. For acyclic imines lower enantiomeric excesses were observed. The reason for this is likely due to the fact that the acyclic imines are mixtures of anti and syn isomers which interconvert during the reaction. The catalyst was found to be tolerant of many functional groups found in organic synthesis. Thus the reaction represents an effective method for the synthesis of chiral cyclic amines.
- Willoughby, Christopher A.,Buchwald, Stephen L.
-
p. 8952 - 8965
(2007/10/02)
-
- La reaction d'ω-azidocetones avec la triphenylphosphine: une voie d'acces generale aux imines cycliques
-
The ω-azidoketones RC(=O)-CH(R')-(CH2)n-CH(R'')-N3 react with triphenylphosphine in anhydrous media to give 5, 6 and 7 membered cyclic imines via an intramolecular aza-Wittig reaction with good yields.A general synthesis of ω-haloketones which are the precursors of the azidoketones was also devised.
- Vaultier, M.,Lambert, P. H.,Carrie, R.
-
-
- Reaction of Organolithium Reagents with Lactim Ethers: Preparation of Cyclic 2-Alkyl Imines or 2,2-Dialkyl Amines
-
The reaction of lactim ethers 1-3 with organolithium reagents has been found to be an effective method for the preparation of cyclic 2-alkyl imines 4-6.The method is most effective for the preparation of 2-aryl and sterically hindered 2-alkyl imines.In addition, treatment of 1-3 with excess organolithium provides a facile route to the rare cyclic 2,2-dialkyl amine derivatives 7-9.These reactions are characterized by mild reaction conditions and good yields and constitute a superior route to the title compounds.
- Zezza, Charles A.,Smith, Michael B.,Ross, Betsy A.,Arhin, Akwasi,Cronin, Patricia L. E.
-
p. 4397 - 4399
(2007/10/02)
-