- Beyond the five and six: Evaluation of seven-membered cyclic anhydrides in the castagnoli-cushman reaction
-
The Castagnoli-Cushman reaction with benzo[d]- oxepine-2,4(1H,5H)-dione as an anhydride component allowed for preparation of 2,3-disubstituted 4-oxo-2,3,4,5-tetrahydro-1H-benzo[d]- azepine-1-carboxylic acids in 21-75% yields and with good trans diastereoselectivity. The method worked with imines generated from aromatic or a-branched aliphatic aldehydes and is amenable for both parallel synthesis and scale-up. The procedure for epimerization of the resulting trans-disubstituted tetrahydrobenzo[d]azepines to their cis isomers was also developed.
- Adamovskyi, Mykhailo I.,Ryabukhin, Sergey V.,Sibgatulin, Dmitriy A.,Rusanov, Eduard,Grygorenko, Oleksandr O.
-
-
Read Online
- Enantioselective Reductive Cyanation and Phosphonylation of Secondary Amides by Iridium and Chiral Thiourea Sequential Catalysis
-
The combination of transition-metal catalysis and organocatalysis increasingly offers chemists opportunities to realize diverse unprecedented chemical transformations. By combining iridium with chiral thiourea catalysis, direct enantioselective reductive cyanation and phosphonylation of secondary amides have been accomplished for the first time for the synthesis of enantioenriched chiral α-aminonitriles and α-aminophosphonates. The protocol is highly efficient and enantioselective, providing a novel route to the synthesis of optically active α-functionalized amines from the simple, readily available feedstocks. In addition, the reactions are scalable and the thiourea catalyst can be recycled and reused.
- Chen, Dong-Huang,Sun, Wei-Ting,Zhu, Cheng-Jie,Lu, Guang-Sheng,Wu, Dong-Ping,Wang, Ai-E,Huang, Pei-Qiang
-
supporting information
p. 8827 - 8831
(2021/03/16)
-
- A BEt3-Base Catalyst for Amide Reduction with Silane
-
Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.
- Yao, Wubing,Fang, Huaquan,He, Qiaoxing,Peng, Dongjie,Liu, Guixia,Huang, Zheng
-
p. 6084 - 6093
(2019/05/24)
-
- A BEt3-Base catalyst for amide reduction with silane
-
Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.
- Yao, Wubing,Fang, Huaquan,He, Qiaoxing,Peng, Dongjie,Liu, Guixia,Huang, Zheng
-
-
- Activation of primary amines by copper(i)-based lewis acid promoters in the solventless synthesis of secondary propargylamines
-
Primary amines are activated by copper(I)-based Lewis acid promoters in an A 3 -coupling one-pot solventless reaction with aldehydes and phenylacetylene for the synthesis of secondary propargylamines. The reaction is promoted by a CuSO 4 /NaI system, a practical precursor of the in situ generated effective CuI/I 2 system, that worked well, but only in a restricted number of examples. Substitution of I 2 with CeCl 3 ·7H 2 O in a one-pot two-step reaction provided good yields and a wider applicability, with the added value given by a safer procedure.
- Cimarelli, Cristina,Navazio, Federica,Rossi, Federico V.,Del Bello, Fabio,Marcantoni, Enrico
-
p. 2387 - 2396
(2019/05/27)
-
- One-Pot Reductive Allylation of Amides by Using a Combination of Titanium Hydride and an Allylzinc Reagent: Application to a Total Synthesis of (-)-Castoramine
-
A one-pot direct reductive allylation protocol has been developed for the synthesis of secondary amines by using titanium hydride and an allylzinc reagent. This protocol is applicable to a broad range of substrates, including acyclic amides, benzamides, α,β-unsaturated amides, and lactams. The stereochemical outcome obtained from the reaction with crotylzinc reagent suggested that the allylation reaction proceeds through a six-membered cyclic transition state. A total synthesis of (-)-castoramine was accomplished by following this protocol for the highly stereoselective construction of contiguous stereocenters.
- Itabashi, Suguru,Shimomura, Masashi,Sato, Manabu,Azuma, Hiroki,Okano, Kentaro,Sakata, Juri,Tokuyama, Hidetoshi
-
supporting information
p. 1786 - 1790
(2018/07/03)
-
- Zinc(II)-Catalyzed Synthesis of Propargylamines by Coupling Aldimines and Ketimines with Alkynes
-
A ZnII-catalyzed reaction between imines, which were derived from unactivated aldehydes or ketones and primary amines or α-amino acid esters, and terminal alkynes has led to the rapid and efficient formation of tri- and tetrasubstituted propargylamines (from aldimines and ketimines, respectively) in good to excellent yields. No additives or extra Lewis acid reagents were required for the imine-alkyne coupling reaction.
- Shehzadi, Syeda Aaliya,Saeed, Aamer,Lemière, Filip,Maes, Bert U. W.,Abbaspour Tehrani, Kourosch
-
supporting information
p. 78 - 88
(2018/03/27)
-
- Aza-Henry reactions on C-Alkyl substituted aldimines
-
The reactivity of C-CH3 substituted N-protected aldimines in aza-Henry addition reactions was compared with that of the analogous trifluoromethylated compounds. C-Alkyl aldimines easily reacted with nitro alkanes under solvent-free conditions and in the absence of catalyst, despite being worse electrophiles than C-CF3 aldimines, they gave the aza-Henry addition only when ZrCl4 was added. The presence of a bulky group on the imine carbon deeply influenced the reactivity.
- Pelagalli, Alessia,Pellacani, Lucio,Scandozza, Elia,Fioravanti, Stefania
-
-
- Factors influencing the regioselectivity of the oxidation of asymmetric secondary amines with singlet oxygen
-
Aerobic amine oxidation is an attractive and elegant process for the α functionalization of amines. However, there are still several mechanistic uncertainties, particularly the factors governing the regioselectivity of the oxidation of asymmetric secondary amines and the oxidation rates of mixed primary amines. Herein, it is reported that singlet-oxygen-mediated oxidation of 1° and 2° amines is sensitive to the strength of the α-C-H bond and steric factors. Estimation of the relative bond dissociation energy by natural bond order analysis or by means of one-bond C-H coupling constants allowed the regioselectivity of secondary amine oxidations to be explained and predicted. In addition, the findings were utilized to synthesize highly regioselective substrates and perform selective amine cross-couplings to produce imines.
- Ushakov, Dmitry B.,Plutschack, Matthew B.,Gilmore, Kerry,Seeberger, Peter H.
-
supporting information
p. 6528 - 6534
(2015/04/22)
-
- Semi-catalytic reduction of secondary amides to imines and aldehydes
-
Secondary amides can be reduced by silane HSiMe2Ph into imines and aldehydes by a two-stage process involving prior conversion of amides into iminoyl chlorides followed by catalytic reduction mediated by the ruthenium complex [Cp(i-Pr3P)Ru(NCCH3)2]PF6 (1). Alkyl and aryl amides bearing halogen, ketone, and ester groups were converted with moderate to good yields under mild reaction conditions to the corresponding imines and aldehydes. This procedure does not work for substrates bearing the nitro-group and fails for heteroaromatic amides. In the case of cyano substituted amides, the cyano group is reduced to imine.
- Lee, Sun-Hwa,Nikonov, Georgii I.
-
supporting information
p. 8888 - 8893
(2014/06/09)
-
- METHOD FOR THE CATALYTIC REDUCTION OF ACID CHLORIDES AND IMIDOYL CHLORIDES
-
The present application relates to methods for the catalytic reduction of acid chlorides and/or imidoyl chlorides. The methods comprise reacting the acid chloride or imidoyl chloride with a silane reducing agent in the presence of a catalyst such as [Cp(Pri3P)Ru(NCMe)2]+[PF6]?.
- -
-
Paragraph 0176; 0188
(2014/08/19)
-
- Catalytic three-component domino reaction for the preparation of trisubstituted oxazoles
-
Multicomponent reactions are attractive for assembling functionalized heterocyclic compounds. To this end, an efficient gold-catalyzed three-component domino reaction to form oxazoles directly from imines, alkynes, and acid chlorides is presented. The reaction proceeds in a single synthetic step by using a gold(III)-N,N'-ethylenebis(salicylimine) (salen) catalyst to give trisubstituted oxazoles in up to 96 % yield. The substrate scope, a mechanistic study exploring the role of the gold catalyst, and the synthetic applications of the oxazole products are discussed. Copyright
- Wachenfeldt, Henrik V.,R?se, Philipp,Paulsen, Filip,Loganathan, Nagarajan,Strand, Daniel
-
supporting information
p. 7982 - 7988
(2013/07/25)
-
- An easy synthesis of α-trifluoromethyl-amines from aldehydes or ketones using the Ruppert-Prakash reagent
-
A small library of structurally diverse primary amines bearing a geminal CF3 group was synthesized on a preparative scale. The synthesis starts with an aldehyde or ketone that reacts with benzylamine yielding the corresponding imine. The latter is then trifluoromethylated with Me 3SiCF3 under acidic conditions to give a benzylalkylamine. In the last step the Pd-mediated hydrogenation of the benzylalkylamines furnishes the title compounds. All synthetic steps are high-yielding; neither the isolation of the intermediates nor the chromatographic purification of the products is necessary.
- Radchenko, Dmytro S.,Michurin, Oleg M.,Chernykh, Anton V.,Lukin, Oleg,Mykhailiuk, Pavel K.
-
supporting information
p. 1897 - 1898
(2013/04/24)
-
- Synthesis of iminonitriles by oxone/tbab-mediated one-pot oxidative three-component strecker reaction
-
Oxidative three-component reaction of aldehydes, amines, and TMSCN in a biphasic solvent system (toluene/H2O) containing Oxone, tetra-n-butylammonium bromide (TBAB) and sodium bicarbonate afforded α-iminonitriles in good to excellent yields. This oxidative Strecker reaction was applicable to a wide range of aldehydes and amines, aromatic or aliphatic, of different electronic and steric properties. Substituted 1-aza-2-cyano-1,3-dienes were also accessible using α,β-unsaturated aldehydes as inputs.
- Gualtierotti, Jean-Baptiste,Schumacher, Xavier,Wang, Qian,Zhu, Jieping
-
p. 1380 - 1386
(2013/07/05)
-
- Asymmetric addition of trimethylsilylcyanide to N-benzylimines catalyzed by recyclable chiral dimeric V(V) salen complex
-
Chiral dimeric vanadium (V) salen complex (10 mol%) derived from 5,5-Methylene di-[(S,S)-{N-(3-tert-butyl salicylidine)-N′-(3′,5′-di-tert-butyl salicylidene)]-1,2-cyclohexanediamine] with vanadyl suphate followed by auto oxidation was used as efficient catalyst for enantioselective Strecker reaction of N-benzylimines with TMSCN at -30 °C. Excellent yield (92%) of α-aminonitrile and high chiral induction was achieved (ee up to 94%) in case of 2-methoxy substituted N-benzylimines in 10 h. The catalytic system worked well up to four cycles with retention of enantioselectivity.
- Khan, Noor-ul H.,Saravanan,Kureshy, Rukhsana I.,Abdi, Sayed H.R.,Sadhukhan, Arghya,Bajaj, Hari C.
-
experimental part
p. 1133 - 1137
(2010/06/13)
-
- Catalytic, asymmetric Strecker reactions catalysed by titaniumIV and vanadiumV(salen) complexes
-
VanadiumV(salen) complex 3 has been found to be an effective catalyst for the asymmetric addition of hydrogen cyanide (generated in situ from trimethylsilyl cyanide) to imines. The best results (up to 81% enantiomeric excess) were obtained for aromatic imines in which the nitrogen atom is protected with a benzyl group and in which the imine bond is not sterically encumbered.
- Blacker, John,Clutterbuck, Lisa A.,Crampton, Michael R.,Grosjean, Christophe,North, Michael
-
p. 1449 - 1456
(2007/10/03)
-
- The simple and selective synthesis of 3-amino-2,2-difluorocarboxylic esters and difluoro-β-lactams using ethyl bromodifluoroacetate in the presence of rhodium catalyst
-
Treatment of imines (5) with ethyl bromodifluoroacetate (1) and Et 2Zn in the presence of RhCl(PPh3)3 in anhydrous medium gave difluoro-β-lactams (7) in good to excellent yields, while 3-amino-2,2-difluorocarboxylic esters (6) were obtained in good yields by adding MgSO4·7H2O to the reaction medium.
- Sato, Kazuyuki,Tarui, Atsushi,Matsuda, Seiji,Omote, Masaaki,Ando, Akira,Kumadaki, Itsumaro
-
p. 7679 - 7681
(2007/10/03)
-
- A straightforward approach towards thiazoles and endothiopeptides via Ugi reaction
-
Endothiopeptides can easily be obtained via Ugi reaction using thio acids as acid components. If isonitriles with an acetal group are applied, the endothiopeptides can directly be converted into thiazoles using TMSCl-NaI under microwave irradiation. The Royal Society of Chemistry 2005.
- Kazmaier, Uli,Ackermann, Stefanie
-
p. 3184 - 3187
(2007/10/03)
-
- Thiourea-Catalyzed Enantioselective Hydrophosphonylation of Imines: Practical Access to Enantiomerically Enriched α-Amino Phosphonic Acids
-
Chiral thiourea 1b catalyzes the highly enantioselective hydrophosphonylation of a wide range of N-benzyl imines. The hydrophosphonylation products are readily deprotected by hydrogenolysis, providing access to free α-amino phosphonic acids in highly enantioenriched form. Copyright
- Joly, Guy D.,Jacobsen, Eric N.
-
p. 4102 - 4103
(2007/10/03)
-
- A stereoselective synthesis of alkynylaziridines
-
Reactions between allenylzinc carbenoid 1 and various imines were examined; trans-substituted alkynylaziridines were produced with excellent diastereoselectivity. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Chemla, Fabrice,Ferreira, Franck,Hebbe, Virginie,Stercklen, Eric
-
p. 1385 - 1391
(2007/10/03)
-
- A one-pot aza-Wittig based solution and polymer supported route to amines
-
This paper presents a high yielding one-pot solution phase and polymer supported synthesis of a range of primary and secondary amines starting from azides and aldehydes. The synthesis utilises a tandem process which begins with an aza-Wittig reaction between the aldehyde and an iminophosphorane, followed by reduction, or organometallic 1,2-addition reaction, of the resultant imine. The requisite iminophosphoranes were accessed using the highly efficient Staudinger reaction between the azide starting material and a phosphine. The process was applicable to the solid phase by the use of polymer supported iminophosphoranes and polymer supported cyanoborohydride.
- Hemming,Bevan,Loukou,Patel,Renaudeau
-
p. 1565 - 1568
(2007/10/03)
-
- A mild, convenient, and inexpensive method for converting imines into amines: Tin-catalyzed reduction with polymethylhydrosiloxane (PMHS)
-
We have developed a mild, convenient, and inexpensive protocol for reducing imines to amines. Thus, treatment of any of a wide array of imines with catalytic n-butyltris(2-ethylhexanoate)tin and stoichioimetric polymethylhydrosiloxane (PMHS) in ethanol at room temperature cleanly affords the desired secondary amine product. Alkyl bromides, alkynes, epoxides, esters, nitriles, and olefins are inert toward these reduction conditions, whereas aldehydes, ketones, and nitro compounds are not.
- Lopez, Rosa M.,Fu, Gregory C.
-
p. 16349 - 16354
(2007/10/03)
-