Regio- and Stereoselective Formation of 1,3-Oxathiolanes by Reactions of Thiocarbonyl Compounds with Oxiranes

Abstract

Lewis acid-catalyzed reactions of oxiranes with a variety of C═S compounds yield 1,3-oxathiolanes. The ring enlargement of monosubstituted oxiranes occurs regioselectively via cleavage of the O,C(3) bond of alkyl substituted oxiranes and the O,C(2) bond of phenyl oxirane. Furthermore, the reaction proceeds with inversion of the configuration at the center of the nucleophilic attack by the S-atom. The formation of thiocarbonylium ions as intermediates is supported by Wagner–Meerwein-type rearrangements. Enolized thioketones react with oxiranes to give enesulfanyl alcohols, which undergo an acid-catalyzed cyclization to yield 1,3-oxathiolanes.     

非对称环氧乙烷的区域选择性亲核开环反应

本文总结了常用亲核试剂对非对称环氧乙烷的亲核开环反应及其区域选择性。强亲核性的亲核试剂通常只受空间效应影响,进攻非对称环氧乙烷位阻小的碳原子,对于烯基取代环氧乙烷还可以进攻烯基的β-碳原子发生S_N2'开环反应,其他亲核试剂同时受空间效应和电子效应的影响,对于烷基环氧乙烷通常进攻其取代少的碳原子, 空间效应起主导作用,而对芳基和烯基取代环氧乙烷开环反应通常发生在环氧乙烷芳甲位和烯丙位的碳原子上, 电子效应起主导作用。在质子酸或强Lewis酸存在下,虽然单烷基环氧乙烷的开环仍然发生在其取代少的碳原子上,但对于芳基、烯基和同碳双取代环氧乙烷,亲核开环反应将主要受电子效应控制,一般亲核试剂倾向于进攻环氧乙烷的芳甲位、烯丙位或多取代的碳原子。分子内的亲核开环反应主要受成环时环大小的控制, 成环时的倾向是五元环> 六元环> 七元环。环氧乙烷亲核开环的区域选择性是环氧乙烷和亲核试剂空间效应和电子效应平衡的结果。     

Pd/C‐Catalyzed Carbonylative Esterification of Aryl Halides with Alcohols by Using Oxiranes as CO Sources

A carbonylative esterification reaction between aryl bromides and alcohols, promoted by Pd/C and NaF in the presence of oxiranes, has been developed. In this process, oxiranes serve as sources of carbon monoxide by their conversion to aldehydes through a palladium‐promoted Meinwald rearrangement pathway. Intramolecular versions of this process serve as methods for the synthesis of lactones and phthalimides.     

Synthesis of Aldehydes from Oxiranes using Silica Gel as Reagent

The rearrangement of some 2-aryl monosubstituted and 2-aryl, 2-methyl disubstituted oxiranes to aldehydes using silica gel in very mild conditions is reported.     

Stereospecific Transformations of Chiral Compounds Using Anchimeric Assistance of Arylthio and Arylseleno Group

A new chiral pool method is developed starting from readily available chiral oxiranes, the key step being the substitution reaction through the anchimeric assistance of the arylthio and arylseleno group. The overall transformation is the introduction of nucleopiles into the chiral carbon of the oxiranes with retention of the configuration.     

Reaction of Oxiranes with Ethyl 3-Phenyl-1H-pyrazole-5-carboxylate

Russian Journal of Organic Chemistry - Ethyl 3-phenyl-1H-pyrazole-5-carboxylate reacted with oxiranes to give mixtures of 2-phenyl-6-R-6,7-dihydro-4H-pyrazolo[5,1-c][1,4]oxazin-4-ones and ethyl...     

Enantioselective epoxidation of unfunctionalized simple olefins by non-racemic molybdenum(VI)(oxo-diperoxo) complexes

Molybdenum(VI)(oxo-diperoxo) complexes bearing bidentate ligands with hydroxy and carbonyl functions show asymmetric induction in the stoichiometric epoxidation of simple prochiral olefins. The influence of the ligand and alkene structure on the enantiomeric excess of the oxiranes has been investigated. The addition of chiral diols to the molybdenum(VI)(oxo-diperoxo) reagents gives high enantiomeric excesses probably because of an efficient kinetic resolution of the oxiranes formed.     

A Facile Solvent‐Free Synthesis of Chiral Oxazolidinone Derivatives Catalyzed by MgI2 Etherate: An Approach to Enantiopure Synthesis of Linezolid

A highly efficient and stereoselective cycloaddition of aryl isocyanates with chiral oxiranes catalyzed by MgI₂ etherate under solvent‐free conditions was developed to prepare the chiral oxazolidinone derivatives. This methodology has been applied into the practical synthesis of antibacterial drug linezolid.     

Enzymatic Ring‐Opening Polymerization of Oxiranes and Dicarboxylic Anhydrides

Oxiranes, such as glycidyl phenyl ether, benzyl glycidate, glycidyl methyl ether, and styrene oxide, were copolymerized with dicarboxylic anhydrides, such as succinic anhydride, phthalic anhydride, and maleic anhydride, by the action of an enzyme in a stepwise reaction to produce the corresponding polyesters containing some ether linkages having a maximum M _w of 13 500. Oxiranes, such as glycidol and glycidyl phenyl ether, were also homopolymerized and copolymerized with other oxiranes by the enzyme to produce the corresponding polyethers.

Enzymatic polymerization of oxiranes and dicarboxylic anhydrides.     

Nitration of Alkenes and Oxiranes with Nitrogen(IV) Oxide in Liquid and Supercritical Carbon Dioxide Media

Doklady Chemistry - For the first time the reactions of radical nitration of alkenes and oxiranes with nitrogen dioxide in the liquid and supercritical carbon dioxide (sc-CO2) media were carried...     

Desulfurization of 2-Thioxo-1,2,3,4-tetrahydropyrimidin-4-ones with Oxiranes and 2-Haloacetonitriles

A procedure was developed for the synthesis of tetrahydropyrimidine-2,4-diones by desulfurization of 2-thioxo-1,2,3,4-tetrahydropyrimidin-4-ones with oxiranes or 2-haloacetonitriles in polar solvents in the presence of a base.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 617–619.Original Russian Text Copyright © 2005 by Novakov, Orlinson, Navrotskii.     

Calcined MgAICO3-HT Catalysed Cyanosilylation of Carbonyl Compounds and Nucleophilic Ring Opening of Oxiranes Using TMSCN

Nucleophilic addition of TMSCN to carbonyl compounds is found to be catalysed efficiently using hydrotalcite as a solid base. The catalyst is also found to be active in the nucleophilic ring opening of oxiranes giving high regioselectivity.     

Spiroacetals from Acetone and Oxiranes - A Simple Route to Optically Active 1,6-Dioxaspiro [4,4]nonane-pheromones

A new and efficient synthetis of 1,6-dioxaspiro[4,4]nonane-spiroacetals, starting from the simple building blocks acetone and oxiranes is described.     

Bismuth(III) Chloride; A Mild and Efficient Catalyst for Synthesis of Thiiranes from Oxiranes

A simple and efficient method for the conversion of oxiranes to the corresponding thiiranes using ammonium thiocyanate (NH₄SCN) and catalytic amounts of bismuth(III) chloride (BiCl₃) is described. The yields obtained are excellent.     

Chiral Thietanes and Thiethane-1, 1-dioxides—Novel Building Blocks for Liquid Crystals -

The synthesis of chiral thietanes and chiral thiiranes from oxiranes under Mitsunobu conditions is described. One chiral thietane was oxidized to the corresponding thietane-1, 1-dioxide. ¹H-NMR, ¹³C-NMR, IR, MS data of the new compounds are given. In connection with a mesogenic group liquid crystal behavior could be observed for the thietane and the thiirane as well.     

An Environmentally Benign Catalytic Method for Efficient and Selective Nucleophilic Ring Opening of Oxiranes by Zirconium Tetrakis(dodecyl Sulfate)

An operationally simple and environmentally benign protocol for a highly regio‐ and chemoselective preparation of β‐substituted alcohols by means of ring‐opening reactions of oxiranes with various aliphatic alcohols, H₂O, NaN₃, and NaCN as nucleophiles in the presence of catalytic amounts of zirconium tetrakis(dodecyl sulfate) as Lewis acid/surfactant‐combined catalysts (LASCs) was developed. The high efficiency of the catalyst was confirmed by the high product yields obtained within desired times and, in particularly by the reusability of the Zr^IV complex.     

Highly Active Aluminium Catalysts for the Formation of Organic Carbonates from CO2 and Oxiranes

Al^III complexes of amino‐tris(phenolate) ligand scaffolds have been prepared to attain highly Lewis acidic catalysts. Combination of the aforementioned systems with ammonium halides provides highly active catalysts for the synthesis of organic carbonates through addition of carbon dioxide to oxiranes with initial turnover frequencies among the highest reported to date within the context of cyclic carbonate formation. Density functional theory (DFT) studies combined with kinetic data provides a rational for the relative high activity found for these Al^III complexes, and the data are consistent with a monometallic mechanism. The activity and versatility of these Al^III complexes has also been evaluated against some state‐of‐the‐art catalysts and the combined results compare favorably in terms of catalyst construction, stability, activity, and applicability.     

Palladium-catalyzed coupling reaction of propargylic oxiranes with arylboronic acids in aqueous media

A novel type of coupling reaction has been developed by the palladium-catalyzed reaction of propargylic oxiranes with arylboronic acids, in which anti-substituted 4-aryl-2,3-allenols were produced in a highly diastereoselective manner. A chiral-substituted allene has been synthesized from the reaction of a chiral propargylic oxirane without loss of the chirality.     

Ferroelectric liquid crystals and dopants containing the chiral thiirane unit. A comparison with analogous oxiranes

The synthesis and mesomorphic properties of a new type of ferroelectric liquid crystals and dopants (for induced ferroelectric phases) containing cis or trans disub-stituted thiiranes as the chiral unit are described. A comparison of the thiiranes with the corresponding oxiranes is given. In the thiirane series the tendency to exhibit mesophases is less pronounced. S*_C phases occur for three aromatic cores in the mesogenic part of the molecule. The temperature ranges of the liquid crystal phases are broader and the transition temperatures are higher in the trans compared with cis configured thiiranes and oxiranes. Cis configured thiiranes exhibit a higher spontaneous polarization than the corresponding trans compounds.     

Asymmetric cyclizations of some chlorohydrins catalyzed by optically active cobalt (salen) type complexes

Optically active chloromethyloxirane was obtained from 1,3-dichloro-2-propanol by a process of asymmetric synthesis. The highest enantiomenc excess (e. e. ) of chloromethyloxirane that could be obtained was 67%, using Co(II) (3,5-Cl,Cl-sal)₂(S-CHXDA) and K₂CO₃ as the catalyst and base, respectively. For purpose of comparison, asymmetric cyclizations of racemic 2,3-dichloro-1-propanol and 2-chloro-1-propanol were examined; optically active chloromethyloxirane and methyloxirane were obtained according to kinetic resolution mechanisms, although the optical purities of oxiranes formed were not so high. The mechanisms for the asymmetric reactions were investigated by circular dichroism and absorption spectroscopies. It was found that the cobalt (salen) type complex forms a new complex with alkali metal carbonate, similarly to the function of crown ether. The substrate interacts with the newly formed chiral complex, followed by cylization to give optically active oxiranes.