Hydrolysis of epoxides and aziridines catalyzed by polymer-supported quarternary ammonium bisulfate

Macroporous resin （D201）-supported quartemary ammonium bisulfate （D201-HSO4） was prepared and effectively used in catalyzing the hydrolysis of epoxides or aziridines under mild and non-metal conditions to give the corresponding 1,2-diols and β-amino alcohols in high yields. The catalyst was facilely prepared and recyclable.     

Highly regioselective ring opening of epoxides and aziridines using (bromodimethyl)sulfonium bromide

Epoxides and aziridines undergo ring opening efficiently with (bromodimethyl)sulfonium bromide at room temperature to form the corresponding β-bromohydrins and β-bromoamines, respectively. The conversions are highly regioselective and afford the products in excellent yields within a short period of time.     

Microwave assisted ring-opening of epoxides with N-biaryl sulfonamides in the synthesis of matrix metalloproteinase-9 inhibitors

A microwave accelerated epoxide ring-opening process with N-biaryl sulfonamides is described. Under this mild, highly efficient condition, an α-hydroxy-β-N-biaryl sulfonamide skeleton is rapidly assembled leading ultimately to a novel series of matrix metalloproteinase-9 inhibitors with single digit nanomolar activities.     

Highly regio- and stereoselective ring-opening of epoxides and aziridines with sodium azide using ammonium-12-molybdophosphate

Epoxides and aziridines undergo ring-opening readily with NaN₃ in the presence of ammonium-12-molybdophosphate to afford the corresponding 2-azidoalcohols and 2-azidoamines in high yields with good regio- and stereoselectivity under mild reaction conditions.     

Direct conversion of epoxides to vic-difluorides

vic-Difluoro compounds can be directly prepared from epoxides by reaction with Et₃N-3HF and DFMBA under microwave-irradiation conditions.     

A mild, rapid and highly regioselective ring-opening of epoxides and aziridines with acetic anhydride under solvent-free conditions using ammonium-12-molybdophosphate

A highly regioselective ring opening of epoxides and aziridines can be carried out efficiently with acetic anhydride to form the acetates of the corresponding 1,2-diols and 2-amino-alcohols, respectively, using ammonium-12-molybdophosphate (AMP) as a heterogeneous catalyst, at room temperature, in the absence of solvent.     

Zirconyl nitrate mediated regioselective ring opening of epoxides and aziridines: an easy synthesis of β-nitrato-alcohols and -sulfonamides

Epoxides and aziridines are cleaved efficiently and regioselectively in the presence of zirconyl nitrate at room temperature to afford the corresponding β-nitrato-alcohols and -sulfonamides, respectively, in high yields.     

Direct synthesis of aliphatic vinyl aziridines

The synthesis of vinyl aziridines, by the reactions of a range of diphenylphosphinyl and p-toluenesulfonyl alkyl aldimines with the ylide derived from S-allyl tetrahydrothiophenium bromide, are reported.     

A convenient and efficient ring-opening reaction of aziridines with acetylenes and synthesis of dihydropyrroles

In the presence of ^tBuOK, 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 Me₃Si-substituted acetylenes but also acetylene itself was suitable reagents. Treatment of ring-opening products with I₂ and AgOAc in the presence of K₂CO₃ 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 I₂ and AgOAc.     

Regioselective ring-opening of aziridines with potassium thiocyanate and thiols using sulfated zirconia as a heterogeneous recyclable catalyst

Ring-opening of aziridines with potassium thiocyanate and thiols has efficiently been carried out at room temperature in the presence of sulfated zirconia to give the corresponding β-aminothiocyanates and β-aminosulfides, respectively, in high yields within 2 h and with high regioselectivity. The catalyst, a solid acid, functions under heterogeneous conditions.     

Graphite oxide: a simple and efficient solid acid catalyst for the ring-opening of epoxides by alcohols

A simple, efficient, and general procedure for the ring-opening of epoxides with various alcohols to give the corresponding β-alkoxy alcohols using graphite oxide (GO) as the catalyst, under very mild reaction conditions is described. The method proceeds in good to excellent yields and in short reaction times at room temperature under metal-free conditions.     

Application of N-thiocyanatosuccinimide as a reagent for the facile conversion of epoxides into thiocyanohydrines

The use of in situ generated N-thiocyanatosuccinimide with NH₄SCN offers an efficient reagent system for the conversion of epoxides into their corresponding thiocyanohydrines in good to high yields.The major advantages of this method are as follows:use of cheap reagent,high regioselectivity,simple availability of reagent,ease of workup of the reaction.     

Quaternary ammoniums and a cationic sodium complex as supramolecular catalysts in ring-opening of epoxides by amines

Supramolecular ionic organocatalysts and a metal-based catalyst were investigated in the ring-opening of epoxides by amines, without any artifice to enhance conversion (i.e., solvophobic effect, extended reaction time, heating, excess of amine, high catalyst loading). Different β-amino-alcohols were obtained in satisfying conversion (50–80%) in 24 h, under mild conditions.     

[F]Fluoroamines via ring-opening of N-Cbz-2-methylaziridine with [F]-fluoride

A highly regioselective method was developed for ring-opening benzyloxycarbonyl (Cbz)-protected 2-methylaziridine with [¹⁸F]-labelled fluoride. Following catalytic hydrogenation, 1-[¹⁸F]fluoro-2-propanamine ([¹⁸F]1) and 2-[¹⁸F]fluoro-1-propanamine ([¹⁸F]2) were prepared as the major and minor products, respectively (85:15), and were characterized following acylation with benzyl chloride. This methodology is applicable towards the generation of new [¹⁸F]-labelled amines for incorporation into radiopharmaceuticals.     

A novel conversion of erythro phospholane epoxides to one-carbon atom homologated allylic alcohols

A novel synthetic approach is described to incorporate one more carbon atom at C-2 position of phospholane oxides as homologated allylic alcohol by treatment of erythro-2,3-epoxy-3-methylphospholane 1-oxides with excess of dimethylsulfonium methylide.     

Investigation of the catalytic activity of an electron-deficient vanadium(IV) tetraphenylporphyrin: A new, highly efficient and reusable catalyst for ring-opening of epoxides

In this work, the catalytic activity of high-valent tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V^IV(TPP)(OTf)₂], in the nucleophilic ring-opening of epoxides is reported. This new V(IV) catalyst was used as an efficient catalyst for alcoholysis with primary (methanol, ethanol and n-propanol), secondary (iso-propanol) and tertiary alcohols (tert-butanol), hydrolysis and acetolysis of epoxides with acetic acid and also for the conversion of epoxides to 1,2-diacetates with acetic anhydride, conversion of epoxides to thiiranes with ammonium thiocyanate and thiourea, and for conversion of epoxides to acetonides with acetone. The catalyst was reused several times without loss of its activity.     

Regio- and stereoselective ring opening of aziridines with nitric oxide

Reaction of N-tosyl aziridines with nitric oxide affords the corresponding ring-opened products in regio-, stereoselectivities and excellent yields.     

Guanidines as a nitrogen source for direct conversion of epoxides to aziridines

Direct conversion of epoxides to aziridines was achieved with guanidines as a nitrogen source. Stereochemical inversion at the chiral centers of epoxides was observed without loss of optical purity.     

Practical and reliable synthesis of dialkyl N-arylphosphoramidates with nitroarenes as substrates

A new single-step transformation of readily available nitroarenes with trialkyl phosphites, which can be performed both under thermal and microwave conditions, delivers dialkyl N-arylphosphoramidates in good yields and short reaction times.     

Influence of multidentate N-donor ligands on highly electrophilic zinc initiator for the ring-opening polymerization of epoxides

A set of multidentate ligands have been synthesized and used to stabilize the putative highly electrophilic zinc species initiating ring-opening polymerization (ROP) of cyclohexene oxide (CHO) and propylene oxide (PO). Reaction of the bidentate C₂-chiral bis(oxazoline) ligand (^R2,R3BOX: R₂ = (4S)-tBu, R₃ = H (a); R₂ = (4S)-Ph, R₃ = H (b); R₂ = (4R)-Ph, R₃ = (5S)-Ph (c)) with Zn(R₁)₂ (R₁ = Et (1), Me (2)) led to the heteroleptic three-coordinate complexes (^R2,R3BOX)ZnR₁, 1a-c and 2a, which were isolated in 92-96% yield. Next, two pyridinyl-functionalized N-heterocyclic carbene (NHC) ligands have been designed and synthesized: the 1,3-bis(2-pyridylmethyl)imidazolinium salt (d) and the protected NHC adduct 2-(2,3,4,5,6-pentafluorophenyl)-1,3-bis(2-pyridylmethyl)imidazolidine (e). The reaction of ligands d and e with ZnEt₂ led directly to the formation of (NHC)ZnEt(Cl) 3d complex with ethane elimination and the adduct (NHC-C₆F₅(H))ZnEt₂4e, respectively, in high yield. In situ combinations of selected complexes 1a-c, 3d and 4e with B(C₆F₅)₃ (1 or 2 equivalents) give active systems for ROP, with high productivity (3.3-5.9 10⁶ g_polym. mol_Zn⁻¹ h⁻¹) and high molecular weight (M_n up to 132 10³ g mol⁻¹) for CHO polymerization. Although the in situ B(C₆F₅)₃-activated zinc species were not isolated, the sterically demanding BOX ligands (1c > 1b > 1a) and functionalized NHC ligands seem to enhance the stability of highly electrophilic zinc complexes over ligand redistribution, allowing a better control of the cationic ROP as reflected particularly for 3d and 4e complexes by their respective efficiency (42-88%).