10.1021/jo010860d
This study presents an asymmetric synthetic approach for the production of enantiomerically pure 3-phenylaziridine-2-carboxylate 7, a key intermediate for the synthesis of α-phenyl-substituted cysteine, tryptophan, and serine derivatives. These novel amino acids are of great interest as they have the potential to enhance the bioactivity and selectivity of peptides by constraining their side chain conformations. The synthesis involves the Sharpless asymmetric dihydroxylation of trans-benzylcinnamate 1 to generate (2R,3S)-diol 2, which is then transformed through a series of reactions involving cyclic sulfite 3, cyclic sulfate 4, and azido alcohols 5 and 6 to ultimately afford the desired aziridine 7. Further reactions with nucleophiles such as 4-methoxybenzyl mercaptan, indole, and acetic acid form the target amino acid derivatives. The chemicals used in the study serve as starting materials, reagents, and solvents in the various synthetic steps, each playing a crucial role in the formation of intermediates and final products.
10.1021/acs.orglett.7b01333
The study presents a magnesium-catalyzed asymmetric ring-opening reaction of aziridines with substituted tetrazoles, resulting in the formation of desymmetrization products with high yields and good enantioselectivities. A new chiral ligand, synthesized from azetidine and (R)-BINOL, was used in the in situ generated magnesium catalyst to achieve these results. The reaction is significant for the synthesis of enantioenriched heterocyclic compounds, which are important in medicinal chemistry due to their presence in many drugs. The study also explores the scope of the reaction with various substituted tetrazoles and provides a proposed mechanism for the Mg(II)-mediated desymmetrization process. The chemicals used in the study include meso-aziridines, substituted tetrazoles, and a series of chiral ligands derived from BINOL, which serve to catalyze the reaction and direct the stereochemistry of the products.
10.1021/jo900381b
The study focuses on the stereoselective synthesis of optically pure trans-aziridines, which are valuable compounds in organic synthesis with applications as ligands, chiral auxiliaries, and structural components in natural products and biologically active molecules. The researchers utilized (R)-N-sulfinylimine and (S)-N-sulfinylimine, which react with a ylide derived from (S)-dimethyl-[2-(ptoluenesulfonyl)phenyl]sulfonium salt, to produce trans-2,3-disubstituted aziridines. The study investigates the effects of the sulfur configuration at the reagents on the newly created chiral centers and observes complete trans selectivity with low facial diastereoselectivity when the configurations match, and total facial diastereoselectivity with a varied cis/trans ratio when they differ. Theoretical calculations suggest that the reaction proceeds mainly through a planar free carbanion. The study serves to develop efficient methods for accessing these compounds and provides insights into the reaction mechanisms and transition state stabilities.
10.1002/chem.201203470
The study explores the synthesis of N-thioacyl-1,2-diamines and N-thioacyl-1,3-diamines through the addition of thioamide dianions to imines and aziridines. The researchers utilized thioamide dianions derived from N-arylmethyl thioamides, which were generated by treating these thioamides with BuLi. These dianions were then reacted with various imines and aziridines to produce the desired N-thioacyl diamines. The study found that the addition reactions with imines proceeded with high diastereoselectivity, yielding products with good-to-excellent yields. The diastereomeric purity of these products could be further enriched through recrystallization. The resulting N-thioacyl-1,2-diamines could be reduced with LiAlH4 to obtain 1,2-diamines, retaining their stereochemistry. The study also investigated the addition of thioamide dianions to aziridines, which showed low diastereoselectivity but high regioselectivity, with the efficiency and regioselectivity improved by the addition of AlMe3. The stereochemistry of the products was confirmed through X-ray diffraction. The study provides a novel method for synthesizing sterically defined 1,2- and 1,3-diamines, which are important structural motifs in natural products, pharmaceuticals, and catalyst ligands.
10.1016/S0957-4166(97)00496-5
The study investigates the copper-catalyzed asymmetric aziridination of olefins, focusing on the impact of different nitrene precursors on the reaction's enantioselectivity and yield. The researchers compared several nitrene precursors, including [N-(4-nitrobenzenesulfonyl)imino]phenyliodinane (lb), p-tolyl analog (la), and others. They found that using lb instead of la significantly improved both the enantioselectivity and chemical yields, with aziridine derivatives obtained in moderate to excellent yields and enantioselectivity up to 95% ee. The study highlights the importance of the nitrene precursor's electronic properties in optimizing the reaction conditions for various olefins. The copper(I) triflate [CuOTf] and chiral bis-oxazoline were used as the catalytic system, and different olefins were tested to evaluate the efficiency of the nitrene precursors. The results suggest that the choice of nitrene source is crucial for achieving high enantioselectivity and yield in the asymmetric aziridination of olefins.
10.1016/0008-6215(88)80154-X
The study explores a novel synthetic route to 1,2-trans-2-amino-2-deoxyglycopyranosides via phosphoramidates of 1,2-trans-2-deoxy-2-iodoglycopyranosyles. The key chemicals involved include 1,2-trans-2-deoxy-2-iodoglycopyranosyl phosphoramidates, which are prepared from corresponding glycals by adding iodoazide followed by a Staudinger reaction with a phosphite. These phosphoramidates react with alcohols in the presence of a base to yield the desired 1,2-trans-2-deoxy-2-phosphoramidoglycopyranosides after inversion of configuration at C-1 and C-2, with an aziridine intermediate being opened by the alcohol present. Simple alcohols are used to produce alkyl glycosides with different configurations (β-D-gluco, β-D-xylo, α-D-manno, and α-D-lyxo) from various phosphoramidates, achieving excellent yields. However, when using an alcohol derived from galactopyranose, the resulting disaccharide is obtained in low yield. The study also involves the use of sodium for neutralization, hydrazine for hydrazinolysis, and palladium on carbon for hydrogenolysis, among other reagents, to transform the phosphoramidates into various derivatives and to confirm the structural rearrangements through chemical synthesis and spectroscopic analysis.
10.1007/s10562-011-0763-3
The study investigates the aminolysis of aziridines catalyzed by samarium diiodide and samarium iodobinaphtholate. Aziridines, which are three-membered heterocyclic compounds with a nitrogen atom, are reacted with aromatic amines to produce 1,2-diamines, which are important scaffolds for biologically active molecules and used in enantioselective catalysis. The researchers found that samarium diiodide efficiently catalyzes the ring-opening of both activated and non-activated aziridines, leading to the formation of various N-diprotected ?-diamines. The study also compared the effectiveness of different N-protecting groups on aziridines, with N-Boc (t-butoxycarbonyl) protection yielding the best results. Additionally, samarium iodobinaphtholate was tested for enantioselective aminolysis of aziridines, showing total conversion but low enantioselectivities, with encouraging results observed for N-Boc aziridines. The reactions were optimized in terms of solvent (THF or DCE) and reaction conditions, with microwave irradiation significantly reducing reaction times.
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