Opening Of Aziridines Research Articles

ChemInform Abstract: Synthesis of β‐Substituted Tryptamines by Regioselective Ring Opening of Aziridines.

Functionalized tryptamines are targets of interest for development as small molecule therapeutics. The ring opening of aziridines with indoles is a powerful method for tryptamine synthesis if site selectivity can be controlled. 4-Nitrobenzyl carbamate (PNZ)-protected aziridines undergo regioselective ring opening to produce β-substituted tryptamines for a series of indoles. The PNZ-protected tryptamines can be further manipulated by PNZ removal under mild conditions.

ChemInform Abstract: Diastereoselective Synthesis of Substituted Tetrahydroisoquinolines and Isoindolines via a Silver(I) Triflate‐Promoted Tandem Reaction.

AbstractA silver(I) triflate‐promoted tandem reaction comprising the ring opening of aziridines and a Michael reaction is developed.

ChemInform Abstract: Zwitterionic Imidazolium Salt: Recent Advances in Organocatalysis

AbstractReview: [50 refs.

ChemInform Abstract: Catalytic Borylative Opening of Propargyl Cyclopropane, Epoxide, Aziridine, and Oxetane Substrates: Ligand Controlled Synthesis of Allenyl Boronates and Alkenyl Diboronates.

AbstractThe borylative ring opening reactions proceed with high regio‐ and stereoselectivity providing alkenyl diboronates or allenyl boronate products selectively depending on the choice of the phosphine ligand.

Synthesis of β-substituted tryptamines by regioselective ring opening of aziridines

Functionalized tryptamines are targets of interest for development as small molecule therapeutics. The ring opening of aziridines with indoles is a powerful method for tryptamine synthesis if site selectivity can be controlled. 4-Nitrobenzyl carbamate (PNZ)-protected aziridines undergo regioselective ring opening to produce β-substituted tryptamines for a series of indoles. The PNZ-protected tryptamines can be further manipulated by PNZ removal under mild conditions.

Construction of functionalized ABEF ring system of C20-diterpenoid alkaloid racemulosine

A continued effort to synthesis of functionalized ABEF tetracyclic ring system of structurally complex C20-diterpenoid alkaloid racemulosine from previously reported tetracyclic aziridine intermediate 3 was described. The synthesis features a regio- and stereoselective ring opening of aziridine and a challenging free radical cyclization reaction to construct functionalized ring B, which could provide a good basis for total synthesis of racemulosine.

Mechanism studies of the chemoselective ring opening of N-tosyl aziridines with aldehydes catalyzed by an N-heterocyclic carbene under aerobic conditions

The mechanism of the reaction of N-tosyl aziridines with aldehyde catalyzed by nucleophilic carbene under aerobic conditions was investigated using B97D method. Two pathways were studied based on experimental reports, and the results show the first pathway is the best one. In the first pathway, the aziridine ring-opening step is the rate-determining step with the free energy of 18.3 kcal mol−1. The addition step of one oxygen molecule to olefin forms the singlet state compound. The oxygen molecule in this system can be utilized as a source of an oxygen atom for the carboxylate product.

Diastereoselective Synthesis of Substituted Tetrahydroisoquinolines and Isoindolines via a Silver(I) Triflate‐Promoted Tandem Reaction

AbstractA new silver(I) triflate‐promoted tandem reaction comprising the ring opening of aziridines and a Michael reaction has been developed. Using secondary amines or primary amines as nucleophiles, this methodology allows for the synthesis of cis‐1‐alkyl‐4‐aminotetrahydroisoquinolines or cis‐1,3‐disubstituted isoindolines in good yields with excellent diastereoselectivities, respectively. Besides, easy operation and mild reaction conditions are also notable features of this tandem reaction.magnified image

Zwitterionic Imidazolium Salt: Recent Advances in Organocatalysis

Imidazole-based zwitterionic-type molten salts have been explored as a new class of organocatalyst in various chemical transformations. It is known that imidazolium motifs provide an unconventional C–H bond for bonding. It is experimentally proven that C2–H of the imidazole moiety plays a crucial role in catalyzing the reaction via electrophilic activation. This review is based on the role of imidazole-based zwitterionic-type molten salts as an organocatalyst for some useful chemical transformations in organic synthesis. One of the most important features of this catalyst is that it can easily be recovered from the reaction media. The recovered catalyst can be reused for subsequent reactions without losing its catalytic activity significantly. 1 Introduction 2 Zwitterionic-type Molten Salt Catalyzed syn-Selective Aza-Henry Reaction 3 Synthesis of 1-(Amidoalkyl)- and 1-(Carbamatoalkyl)-2-naphthols 4 Synthesis of 3-Aminoalkylated Indoles 5 Synthesis of Highly Substituted Imidazoles 6 Synthesis of 5-Substituted 1H-Tetrazoles by the Cycloaddition of Arenecarbonitriles with Sodium Azide 7 Synthesis of 4-Arylidene-2-phenyloxazol-5(4H)-ones 8 Zwitterion-Promoted Ethylene Methoxycarbonylation 9 Synthesis of 5,6-Unsubstituted 1,4-Dihydropyridines 10 Regioselective Ring Opening of Aziridines 11 Conclusions

3 + 2] cycloaddition reaction of azomethine ylides generated by thermal ring opening of aziridines onto carbon nanohorns

Functionalization of carbon nanohorns via [3 + 2] cycloaddition of azomethine ylides generated by thermal ring opening of aziridines.

ChemInform Abstract: A Synthetic Route to Chiral Dihydrobenzothiazines Through Ring Opening of Activated Aziridines with 2‐Halothiophenols/Copper‐Powder‐Mediated C—N Cyclization.

AbstractRegio‐ and stereoselective base‐promoted ring opening of aziridines with o‐halothiophenols and subsequent Cu‐catalyzed intramolecular nucleophilic aromatic substitution offers a straightforward synthetic route to dihydrobenzothiazine derivatives.

Catalytic Borylative Opening of Propargyl Cyclopropane, Epoxide, Aziridine, and Oxetane Substrates: Ligand Controlled Synthesis of Allenyl Boronates and Alkenyl Diboronates

AbstractA new copper‐catalyzed reaction for the stereo‐ and regioselective synthesis of alkenyl diboronates and allenyl boronates is presented. In this process propargyl derivatives of strained three/four‐membered rings were employed as substrates and B2pin2 was used as the boronate source. Selective formation of the alkenyl diboronate versus the allenyl boronate products was controlled by the choice of phosphine ligand.

Catalytic Borylative Opening of Propargyl Cyclopropane, Epoxide, Aziridine, and Oxetane Substrates: Ligand Controlled Synthesis of Allenyl Boronates and Alkenyl Diboronates.

A new copper‐catalyzed reaction for the stereo‐ and regioselective synthesis of alkenyl diboronates and allenyl boronates is presented. In this process propargyl derivatives of strained three/four‐membered rings were employed as substrates and B2pin2 was used as the boronate source. Selective formation of the alkenyl diboronate versus the allenyl boronate products was controlled by the choice of phosphine ligand.

ChemInform Abstract: Lewis Acid Promoted Three‐Component Reactions of Aziridines, Arenes and Aldehydes: An Efficient and Diastereoselective Synthesis of cis‐1,4‐Disubstituted Tetrahydroisoquinolines.

Abstract A new Lewis acid promoted three-component reaction between the aziridine, arene and aldehyde has been developed. This reaction involves sequential ring opening of aziridine and Pictet–Spengler condensation and gives a broad range of cis-1,4-disubstituted tetrahydroisoquinolines in moderate yields with good diastereoselectivities under mild conditions. The methodology provides a rapid and convergent synthesis for the scaffold of tetrahydroisoquinoline and serves as a good tool for constructing the libraries of substituted tetrahydroisoquinolines.

ChemInform Abstract: Generation and Ring Opening of Aziridines in Telescoped Continuous Flow Processes.

AbstractVarious N‐sulfonyl aziridines are synthesized from 1,2‐amino alcohols under continuous flow conditions.

ChemInform Abstract: Reactivity of Aziridinium Salts in Different Solvents Unraveled by a Combined Theoretical and Experimental Approach

This chapter focuses on the importance of aziridinium ions as intermediates in organic chemistry. The principal aim is to gain insight into the factors to take into account for the selective synthesis of a variety of functionalized amines via aziridinium salts, such as the nature of the aziridinium ion (ring strain and N- and C-substituents of the aziridine ring), the nucleophile, and the solvent environment. Molecular modeling is used to investigate kinetics, electrostatics, and frontier molecular orbitals of reactions involving intermediate aziridinium ions, such as the nucleophilic ring opening of aziridines, the ring expansion of nitrogen heterocycles, and the ene reactions with triazolinedione. Open image in new window

A Modular Synthesis of Multidentate S-, N- and O-Containing Meta- and Paracyclophanes

© 2015 Wiley-VCH Verlag GmbH andCo. KGaA, Weinheim. The development of a modular approach to macrocycle assembly has enabled the synthesis of a library of pyridine-based macrocycles possessing multiple donor sites where chirality was readily introduced from (R)- or (S)-alanine, a representative amino acid. The facile, regioselective, nucleophilic ring opening of aziridines by dithiols enabled the synthesis of thioether-based linkers which on subsequent alkylation provided access to optically pure macrocycles. A modular approach to macrocyclic assembly has enabled the synthesis of a library of macrocycles possessing multiple donor sites where chirality was readily introduced from (S)-alanine. Key to this approach was the facile, regioselective, nucleophilic ring opening of aziridines by dithiols followed by macrocylisation under conditions of high dilution.

Chiral aziridine ring opening: facile synthesis of (R)-mexiletine and (R)-phenoxybenzamine hydrochloride

A simple and efficient synthesis of chiral drugs (R)-mexiletine 1, an anti-arrhythmic drug and (R)-phenoxybenzamine hydrochloride 2, an anti-hypertensive drug has been described via controlled reductive ring opening of chiral aziridine as a key step. The target compounds 1 and 2 were obtained in overall yields of 34% and 10.5%, respectively.

Generation and Ring Opening of Aziridines in Telescoped Continuous Flow Processes

A simple method for the preparation of a variety of N-sulfonyl aziridines (10 examples) from 1,2-amino alcohols under continuous flow conditions is described. Using flow based methods, the aziridines can be further ring opened with oxygen, carbon, and halide nucleophiles or ring expanded to imidazolines by Lewis acid promoted reaction with nitriles. Telescoping the aziridine generation and ring opening steps together in a microfluidic reactor allows the chemistry to be undertaken with limited exposure to the potentially hazardous aziridine intermediates.

ChemInform Abstract: A Novel and Selective Fluoride Opening of Aziridines by XtalFluor‐E. Synthesis of Fluorinated Diamino Acid Derivatives.

ChemInform Abstract: A Novel and Selective Fluoride Opening of Aziridines by XtalFluor‐E. Synthesis of Fluorinated Diamino Acid Derivatives.