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1.
Michał Rachwalski Stanisław Leśniak Piotr Kiełbasiński 《Tetrahedron: Asymmetry》2010,21(15):1890-1892
Enantiomerically pure tridentate heteroorganic catalysts, containing hydroxyl, sulfinyl, and aziridine moieties, have proven to be highly efficient in the enantioselective conjugate diethylzinc addition to chalcone and cyclohexenone to give the desired products in very high yields (up to 95%) and with ee’s up to 93%. The influence of the stereogenic centers located on the sulfinyl sulfur atom and in the aziridine moiety on the stereochemical course of the reaction is discussed. 相似文献
2.
Stanisław Leśniak Michał Rachwalski Ewelina Sznajder Piotr Kiełbasiński 《Tetrahedron: Asymmetry》2009,20(20):2311-2314
New tridentate enantiomerically pure heteroorganic catalysts, containing hydroxyl, sulfinyl, and aziridine moieties, have proven to be highly efficient in the enantioselective diethylzinc addition to aryl and alkyl aldehydes to give the desired products in very high yields (up to 99%) and with ee’s up to 97%. The influence of the stereogenic centers located on the sulfinyl sulfur atom and in the aziridine moiety on the stereochemical course of the reaction are discussed. 相似文献
3.
Michał Rachwalski Stanisław Leśniak Piotr Kiełbasiński 《Tetrahedron: Asymmetry》2010,21(21-22):2687-2689
Diastereomerically pure tridentate heteroorganic ligands containing hydroxyl, sulfinyl and aziridine moieties as nucleophilic centers, capable of binding to various organometallic reagents, have been proven to be highly efficient catalysts in the enantioselective addition of phenylethynylzinc to aldehydes to give the desired products in very high yields (up to 95%) and with ee’s up to 90%. The influence of the stereogenic centers located on the sulfinyl sulfur atom and in the aziridine moiety on the stereochemical course of the reaction is also discussed. 相似文献
4.
Szymon Jarzyński Greta Utecht Stanisław Leśniak Michał Rachwalski 《Tetrahedron: Asymmetry》2017,28(12):1774-1779
Enantiomerically pure, chiral secondary and tertiary aziridine alcohols (including the aziridine analogue of ProPhenol—AziPhenol) have proven to be highly effective catalysts for enantioselective asymmetric reactions in the presence of zinc ions, including arylation of aromatic aldehydes, epoxidation of chalcone and addition of diethylzinc to aldehydes, leading to the desired chiral products in high chemical yields (up to 90%) and with ee’s up to 90%. A higher catalytic activity of Prophenol-type bis(aziridine alcohol) in the aforementioned asymmetric transformations has been demonstrated. 相似文献
5.
Diastereomerically pure heteroorganic catalysts built on the chiral scaffold of (S)-(+)-mandelic acid and containing secondary hydroxyl and aziridine moieties, have proven to be highly efficient for the enantioselective conjugate diethylzinc addition to chalcone and 2-cyclohexen-1-one to afford the desired chiral adducts in high yields (up to 92%) and with ee’s of up to 90%. The influence of the stereogenic center located at the aziridine moiety on the stereochemical outcome is also discussed. 相似文献
6.
Michał Rachwalski Szymon Jarzyński Marcin Jasiński Stanisław Leśniak 《Tetrahedron: Asymmetry》2013,24(11):689-693
A straightforward synthesis of a series of new catalysts containing secondary hydroxyl and aziridine moieties as nucleophilic centers built on the chiral scaffold of (S)-(+)-mandelic acid is described. The new compounds have been tested for the enantioselective addition of diethylzinc and phenylethynylzinc to aryl and alkyl aldehydes, which yielded the corresponding chiral alcohols in high chemical yields (up to 95%) and with excellent ee’s of ca. 90%. The strong influence of the stereogenic center located at the aziridine subunit on the stereochemical outcome is also reported on. 相似文献
7.
Stanisław Leśniak Michał Rachwalski Szymon Jarzyński Emilia Obijalska 《Tetrahedron: Asymmetry》2013,24(20):1336-1340
A straightforward synthetic route to a series of new catalysts bearing secondary hydroxyl and aziridine moieties as nucleophilic centers built on the chiral skeleton of (S)-(+)-lactic acid is described. All of the new compounds have been tested in the enantioselective addition of diethyl- and phenylethynylzinc to aryl and alkyl aldehydes, yielding the corresponding chiral alcohols in high chemical yields (up to 85%) and good ee’s of approximately 85%. The influence of the stereogenic center located at the aziridine subunit on the stereochemical outcome is also discussed. 相似文献
8.
Liang JL Huang JS Yu XQ Zhu N Che CM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(7):1563-1572
Chiral metalloporphyrins [Mn(Por*)(OH)(MeOH)] (1) and [Ru(Por*)(CO)(EtOH)] (2) catalyze asymmetric aziridination of aromatic alkenes and asymmetric amidation of benzylic hydrocarbons to give moderate enantiomeric excesses. The mass balance in these nitrogen-atom-transfer processes has been examined. With PhI=NTs as the nitrogen source, the aziridination of styrenes, trans-stilbene, 2-vinylnaphthalene, indene, and 2,2-dimethylchromene catalyzed by complex 1 or 2 resulted in up to 99 % substrate conversions and up to 94 % aziridine selectivities, whereas the amidation of ethylbenzenes, indan, tetralin, 1-, and 2-ethylnaphthalene catalyzed by complex 2 led to substrate conversions of up to 32 % and amide selectivities of up to 91 %. Complex 1 or 2 can also catalyze the asymmetric amidation of 4-methoxyethylbenzene, tetralin, and 2-ethylnaphthalene with "PhI(OAc)(2) + NH(2)SO(2)Me", affording the N-substituted methanesulfonamides in up to 56 % ee with substrate conversions of up to 34 % and amide selectivities of up to 92 %. Extension of the "complex 1 + PhI=NTs" or "complex 1 + PhI(OAc)(2) + NH(2)R (R=Ts, Ns)" amidation protocol to a steroid resulted in diastereoselective amidation of cholesteryl acetate at the allylic C-H bonds at C-7 with substrate conversions of up to 49 % and amide selectivities of up to 90 % (alpha:beta ratio: up to 4.2:1). An aziridination- and amidation-active chiral bis(tosylimido)ruthenium(VI) porphyrin, [Ru(Por*)(NTs)(2)] (3), and a ruthenium porphyrin aziridine adduct, [Ru(Por*)(CO)(TsAz)] (4, TsAz=N-tosyl-2- (4-chlorophenyl)aziridine), have been isolated from the reaction of 2 with PhI=NTs and N-tosyl-2-(4-chlorophenyl)aziridine, respectively. The imidoruthenium porphyrin 3 could be an active species in the aziridination or amidation catalyzed by complex 2 described above. The second-order rate constants for the reactions of 3 with styrenes, 2-vinylnaphthalene, indene, ethylbenzenes, and 2-ethylnaphthalene range from 3.7-42.5x10(-3) dm(3) mol(-1) s(-1). An X-ray structure determination of complex 4 reveals an O- rather than N-coordination of the aziridine axial ligand. The fact that the N-tosylaziridine in 4 does not adopt an N-coordination mode disfavors a concerted pathway in the aziridination by a tosylimido ruthenium porphyrin active species. 相似文献
9.
Katagiri T Katayama Y Taeda M Ohshima T Iguchi N Uneyama K 《The Journal of organic chemistry》2011,76(22):9305-9311
The preparation of optically pure α-trifluoromethyl-α-amino acids from N-tosyl-2-trifluoromethyl-2-alkyloxycarbonylaziridine is described. Optically pure aziridine was prepared with a 60% yield via three steps from optically pure 2,3-epoxy-1,1,1-trifluoropropane (TFPO). Ring-opening reactions of the aziridine with a variety of nucleophiles and subsequent deprotection of the N-tosyl moieties gave the optically pure β-substituted-α-trifluoromethyl-α-amino acids in moderate to good yields (up to 85%) without racemization at the quaternary stereogenic center of the amino acid. 相似文献
10.
Xiaojuan Wang Wenxian Zhao Gaowei Li Jin Wang Guanjun Liu Lantao Liu Ruijuan Zhao Mincan Wang 《应用有机金属化学》2014,28(12):892-899
A family of enantiopure β‐aminoalcohols based on aziridine backbones were synthesized, and examined as chiral ligands for the copper(II)‐catalyzed asymmetric Henry reaction of aromatic aldehydes with nitromethane, giving β‐nitroalcohols in excellent yields (up to 93%) and moderate to good enantioselectivities (up to 82%). Moreover, possible transition states of the reaction are proposed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
11.
The chemoselective and diastereoselective synthesis of syn-α-bromo-α-fluoro-β-lactams was achieved using the diethylzinc-mediated Reformatsky-type reaction of ethyl dibromofluoroacetate with imines. The reaction led to diastereomerically pure β-lactams in good to moderate yields (up to 78% yield) with only small amounts of aziridine derivatives. Noncyclized 3-amino-2-bromo-2-fluoro carboxylic esters, usual Reformatsky adducts, were not formed. In contrast, reactions carried out under typical Reformatsky conditions using zinc metal were poorly chemoselective, leading to mixtures of β-lactams and aziridine derivatives. 相似文献
12.
Braga AL Milani P Paixão MW Zeni G Rodrigues OE Alves EF 《Chemical communications (Cambridge, England)》2004,(21):2488-2489
Chiral aziridine sulfides and disulfides were synthesized from readily available and inexpensive R-cysteine by a Mitsunobu reaction; their application in the addition of diethylzinc to aldehydes provides secondary alcohols with up to 99% ee and S-configuration. 相似文献
13.
The enantioselective ring opening of aziridines using a latent source of HF is described. A combination of two Lewis acids, (salen)Co and an achiral Ti(IV) cocatalyst, provided optimal reactivity and enantioselectivity for the trans β-fluoroamine product. The use of a chelating aziridine protecting group was crucial. Acyclic and cyclic meso N-picolinamide aziridines underwent fluoride ring opening in up to 84% ee, and the kinetic resolution of a piperidine-derived aziridine was performed with krel=6.6. The picolinamide group may be readily removed without epimerization of the fluoroamine. Preliminary studies revealed a bimetallic mechanism wherein the chiral (salen)Co catalyst delivers the nucleophile and the Ti(IV) cocatalyst activates the aziridine. 相似文献
14.
Jianke Pan Jia‐Hong Wu Hongkui Zhang Xiaoyu Ren Jian‐Ping Tan Lixiang Zhu Hong‐Su Zhang Chunhui Jiang Tianli Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(22):7503-7508
The first enantioselective aza‐Darzens reaction of cyclic imines with α‐halogenated ketones was realized under mild reaction conditions by using amino‐acid‐derived bifunctional phosphonium salts as phase‐transfer promoters. A variety of structurally dense tri‐ and tetrasubstituted aziridine derivatives, containing benzofused heterocycles as well as spiro‐structures, were readily synthesized in high yields with excellent diastereo‐ and enantioselectivities (up to >20:1 d.r. and >99.9 % ee). The highly functionalized aziridine products could be easily transformed into different classes of biologically active compounds. 相似文献
15.
《Tetrahedron: Asymmetry》2014,25(3):219-223
The facile synthesis of a series of novel catalysts bearing a tertiary hydroxyl group and an aziridine moiety as chelating centers constructed on the scaffold derived from limonene oxide is described. The newly prepared compounds have been tested for the enantioselective addition of diethylzinc and phenylethynylzinc to aryl and alkyl aldehydes, affording the corresponding chiral alcohols in very high chemical yields (up to 96%) and with excellent ee’s of ca. 95%. 相似文献
16.
Highly diastereoselective Lewis acid mediated aza-Diels-Alder reactions of chiral auxiliary derivatized 2H-azirines have been accomplished for the first time, yielding bi and tri-cyclic heterocyclic compounds, comprising aziridine and tetrahydropyridine substructures, in up to 97% de; with the absolute stereochemistry of the major product confirmed by X-ray crystallography. 相似文献
17.
Sven P. Fritz Zulfiquar Ali Matthew G. Unthank Eoghan M. McGarrigle Varinder K. Aggarwal 《Helvetica chimica acta》2012,95(12):2384-2398
A versatile and simple method is reported for the synthesis of bicyclic epoxide and aziridine? fused heterocycles (up to 98% yield, up to 96 : 4 er or up to 15 : 1 dr), using a tandem Michael addition/Johnson? Corey? Chaykovsky annulation approach. A new chiral (2‐bromoethyl)sulfonium reagent is described, based on an easily available chiral sulfide; it promotes or enhances stereoselectivity in the reaction. 相似文献
18.
A General Strategy for the Synthesis of Enantiomerically Pure Azetidines and Aziridines through Nickel‐Catalyzed Cross‐Coupling 下载免费PDF全文
Dr. Kim L. Jensen Dennis U. Nielsen Prof. Dr. Timothy F. Jamison 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7379-7383
In this communication, we report a straightforward synthesis of enantiomerically pure 2‐alkyl azetidines. The protocol is based on a highly regioselective nickel‐catalyzed cross‐coupling of aliphatic organozinc reagents with an aziridine that features a tethered thiophenyl group. Activation by methylation transforms the sulfide into an excellent leaving group and triggers the formation of the 2‐substituted azetidine core structure by cyclization. In addition, we have expanded this concept to the synthesis of enantiomerically pure, terminal alkyl aziridines. Coupling of a TMS‐protected aziridine alcohol, followed by acidic work‐up to remove the silyl group, provides 1,2‐amino alcohol products that are readily cyclized to aziridines. Both of these sequences display excellent functional group tolerance and deliver the desired azetidine and aziridine products in good to excellent yields. 相似文献
19.
Enantiospecific total synthesis of (-)-polyoxamic acid using 2,3-aziridino-gamma-lactone methodology
The non-natural enantiomer of polyoxamic acid was synthesized in six steps from 2,3-aziridino-gamma-lactone 7 with an overall yield of 10%. The key step of the strategy is a deprotection-protection sequence on the nitrogen atom of the aziridine ring required for aziridine activation toward nucleophilic ring opening. 相似文献
20.
A series of new optically pure phosphine oxides containing chiral aziridine subunit were synthesized in good yields and applied as organocatalysts in asymmetric Michael reaction of various aliphatic aldehydes with β-nitrostyrene. The corresponding organocatalysts were synthesized starting from optically pure aziridines in a few simple efficient steps. The appropriate Michael adducts were obtained in most cases in very high chemical yield (up to 97%), excellent enantioselectivity (up to 98% of ee) and diastereoselectivity (up to 95:5 of dr). 相似文献