Ring-Opening Reactions Of Aziridines Research Articles

Unexpected Ring-Opening Reactions of Aziridines with Aldehydes Catalyzed by Nucleophilic Carbenes under Aerobic Conditions

[reaction: see text] The chemoselective ring opening of N-tosyl aziridines with aldehydes catalyzed by an N-heterocyclic carbene was investigated under aerobic conditions. Unexpected carboxylates of 1,2-amino alcohols from the corresponding aldehydes, rather than the acyl anion ring-opened beta-amino ketones, were exclusively obtained. A plausible mechanism for this unprecedented carbene-mediated reaction was also proposed.

A Convenient and Efficient Ring-Opening Reaction of Aziridines with Acetylenes and Synthesis of Dihydropyrroles.

Abstract In the presence of t BuOK, reaction of acetylenes with N -Ts substituted aziridines derived from both cyclic and acyclic alkenes at room temperature gave rise to homopropargylamines in good to high yields and in high regioselectivity. Not only Ph- and Me 3 Si-substituted acetylenes but also acetylene itself was suitable reagents. Treatment of ring-opening products with I 2 and AgOAc in the presence of K 2 CO 3 provided dihydropyrroles in high yields. One-pot synthesis of dihydropyrroles was also realized by the reaction of aziridines and phenylacetylene in the presence of NaH followed by the treatment with I 2 and AgOAc.

Chemistry of Tetrathiomolybdate: Aziridine Ring Opening Reactions and Facile Synthesis of Interesting Sulfur Heterocycles

Benzyltriethylammonium tetrathiomolybdate, [BnEt3N]2MoS4, has been used successfully to effect ring opening of aziridines in a regiospecific and stereospecific manner under mild reaction conditions without the use of Lewis acid catalyst. Utility of this reagent in tandem and multistep processes in a one-pot operation for the synthesis of various novel sulfur heterocycles in very good yield is also reported.

Selectivity aspects of the ring opening reaction of 2-alkenyl aziridines by carbon nucleophiles

A series of common organometallic reagents were used in the reaction with an acyclic and a cyclic activated 2-alkenyl aziridines and the selectivity aspects for each aziridine was addressed.

An Efficient Ring-Opening Reaction of Aziridines with Alkynes Catalyzed by CuOTf

The alkynylation of activated aziridines in the presence of a catalytic amount of CuOTf provided the corresponding ring-opened products in high yields.

A Stereoselective Synthesis of a Key Intermediate to 1β‐Methylcarbapenem via Aziridine Ring‐Opening Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Ring-opening reactions of iminosugar-derived aziridines: application to the general synthesis of α-1- C-substituted derivatives of fagomine

A general approach to α-1- C-substituted derivatives of fagomine (2-deoxynojirimycin-α- C-glycosides) by ring-opening reactions of an aziridine with various heteroatomic nucleophiles, including thiol, amine, alcohol, carboxylate and phosphate, is reported. The nine-step reaction sequence proceeded in an overall yield of 14–28% from tri- O-benzyl- d-glucal. In the course of this study, the synthesis of α-1- C-ethyl-fagomine as well as of 1, N-anhydro derivatives of fagomine has been achieved for the first time.

Synthesis and Structure—Activity Relationship of Novel Aminotetralin Derivatives with High μ Selective Opioid Affinity.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Stereoselective Synthesisof a Key Intermediate to 1β-Methylcarbapenem via AziridineRing-opening Reaction

A stereocontrolled synthesis of azetidinone 3 as a key intermediate to 1β-methylcarbapenem 2 has been achieved via iodoamidation of trichloroacetimidate prepared from (Z)-olefinic allylic alcohol 6, aziridine ring-opening reaction with cyanide nucleophile and a tandem β-lactam formation.

Efficient ring-opening reaction of epoxides and aziridines promoted by tributylphosphine in water.

Tributylphosphine was found to be an effective promoting reagent for the ring-opening reaction of various epoxides and aziridines with nucleophile to produce corresponding anti-bifunctional products in moderate to excellent yields in water.

Synthesis and structure–activity relationship of novel aminotetralin derivatives with high μ selective opioid affinity

Several novel racemic aminotetralin derivatives have been prepared using a stereoselective aziridine ring opening reactions and were evaluated for their μ-opioid receptor binding affinity. Selectivity index towards other opioid receptors and antinociceptive activity in mice have been evaluated for the most potent derivatives.

Regioselective and stereoselective nucleophilic ring opening reactions of a phenyl-substituted aziridine: enantioselective synthesis of beta-substituted tryptophan, cysteine, and serine derivatives.

The asymmetric synthesis of beta-phenyl-substituted cysteine, tryptophan, and serine derivatives was successfully developed. In this approach, the key intermediate, enantiomerically pure 3-phenylaziridine-2-carboxylic ester 7, was prepared from alpha,beta-unsaturated ester 1 by employing the Sharpless asymmetric dihydroxylation. The aziridine 7 was treated with 4-methoxybenzylthiol, indole, and acetic acid to give beta-phenyl-substituted cysteine, tryptophan, and serine, respectively, in a clean S(N)2 type ring opening at the C3 position. This general approach can be used to synthesize a variety of beta-substituted novel amino acids.

Aziridine ring-opening reactions with chiral enolates. Stereocontrolled synthesis of 5-substituted-3-methyl-pyrrolidin-2-ones.

A procedure for performing stereocontrolled aziridine ring-opening reactions with chiral enolates derived from (S,S)-(+)-pseudoephedrine amides has been developed leading to gamma-aminoamides in good yields. The diastereoselectivity of the reaction becomes controlled by the presence of the chiral auxiliary on the enolate, although the stereogenic center contained in the structure of the aziridine has a striking influence on the stereochemical course of the reaction which results in the presence of the corresponding matched and mismatched combinations. Besides, the sense of the asymmetric induction of the chiral auxiliary has resulted to be the opposite to the one found with other type of electrophiles, although it is in good agreement with the trend observed in the reaction of the same kind of enolates with epoxides. Finally, the obtained gamma-aminoamide adducts were converted into enantiopure gamma-amino acids, gamma-aminoesters, and pyrrolidin-2-ones using easy to perform and high yielding reactions.

Synthesis, resolution, and absolute configuration of trans-1-amino-2-dimethylaminocyclohexane

Racemic trans-1-amino-2-dimethylaminocyclohexane was prepared by aziridine ring opening reaction of 7-azabicyclo[4.1.0]heptane with HNMe2. The resolution of the racemate was accomplished by crystallization as the l-tartrate. The optical purity of this material was checked by NMR after derivatization to the corresponding 10-camphorsulfonamide to be >95% ee. The absolute configuration of the R,R-enantiomer was confirmed by X-ray single crystal diffraction of a bis(diammine)copper complex.

An efficient procedure for cleavage of aziridines with various thiols promoted by ZnCl2

The ring-opening reaction of aziridines with various thiophenols and thiols catalyzed by ZnCl2 provides β-amino sulfides in high yield.

Asymmetric synthesis of (R)‐6‐amino‐1‐methyl‐4‐(3‐methyl‐benzyl)hexahydro‐1H‐1,4‐diazepine from L‐asparagine

AbstractAn efficient asymmetric synthesis of (R)‐6‐amino‐1‐methyl‐4‐(3‐rnethylbenzyl)hexahydro‐1H‐1,4‐diazepine [(R)‐2] which serves as the amine part of (R)‐1, a potent and selective 5‐HT3 receptor antagonist, is described. Formation of the hexahydro‐1H‐1,4‐diazepine ring was achieved by the intramolecular ami‐dation of the optically active aminocarboxylic acid 18 or reductive cyclization of the optically active aminoaldehyde 25. Compounds 18 and 25 were prepared from L‐asparagine via the key aziridine derivatives 15 and 22, respectively, with retention of the configuration. The intramolecular aziridine ring opening reaction of 29 gave the C2N bond cleavage product of the aziridine ring, the piperazin‐5‐one 30, as the main product along with the desired 7‐membered ring, the hexahydro‐1H‐1,4‐diazepine product 19.

Preparation and Ring-Opening Reactions of N-Diphenylphosphinyl Vinyl Aziridines

Preparation and Ring-Opening Reactions of N-Diphenylphosphinyl Vinyl Aziridines

Exploratory Investigations Probing a Preparatively Versatile, Pyridinium Salt Photoelectrocyclization−Solvolytic Aziridine Ring Opening Sequence

A novel pyridinium salt photoelectrocyclization-nucleophilic bicyclic aziridine ring opening reaction sequence has been investigated in order to determine its preparative potential. N-Alkylpyridinium perchlorates were found to undergo photoinduced electrocyclization upon irradiation in nucleophilic solvents, such as H(2)O and MeOH, to efficiently produce 6-alkyl-6-azabicyclo[3.1.0]hex-2-en-4-yl alcohols and ethers. The bicyclic aziridine photoproducts react with a number of different nucleophiles (e.g., H(2)O, MeOH, AcOH, AcSH) under acid-catalyzed conditions to produce 5-(nucleophile-substituted)-4-(alkylamino)cyclopenten-3-yl alcohols and ethers. The aziridine ring opening processes are both regioselective and stereoselective, yielding trans,trans-trisubstituted cyclopentenes exclusively, apparently as a consequence of the operation of an SN(2) mechanism. The effects of C-alkyl substitution on the regiochemistry of the pyridinium cation photocyclization reaction were briefly probed, and a method was developed to produce trans,cis-trisubstituted cyclopentenes by use of this tandem preparative sequence.

Synthesis of α- L-fucopyranosyl disaccharides with thioglycosidic linkages and characterization of α- L-fucosidases from bovine kidney and epididymis by their inhibitory activities

Sulfur-linked disaccharide analogs of three α- L-fucopyranosyl 2-acetamido-2-deoxy-β- D-glucopyranosides and one α- L-fucopyranosyl β- D-galactopyranoside were synthesized by substitution reactions of sulfonates and ring-opening reactions of aziridine as well as oxirane derivatives using 1-thio-α- L-fucopyranose as nucleophile. Fucosidases from bovine kidney and epididymis were inhibited by all of these disaccharide analogs and their Ki values range from 0.65 to 4.9 mM.

Synthesis of 1→6,1→4 and 1→3 linked 1-thio-α- L-fucopyranosyl 2-acetamido-2-deoxy-β- D-glucopyranosides and 1→2 linked β- D-galactopyranoside, and their linkage-specific inhibitory activities toward α- L-fucosidases

Sulfur-linked disaccharides analogs of three α- L-fucopyranosyl 2-acetamido-2-deoxy-β- D-gluco pyranosides and one α- L-fucopyranosyl β- D-galactopyranoside were synthesized by substitution reactions of sulfonates and ring-opening reactions of aziridine as well as oxirane derivatives using 1-thio-α- L-fucopyranose derivative as nucleophile. Fucosidases from bovine kidney and epididymis were inhibited by all of these disaccharide analogs and their Ki values range from 0.65 to 4.9 mM.