- [2,3] Sigmatropic rearrangement of unstable sulfur ylides from allyl sulfonium salts. Comparative study of electrochemical reduction with the base method and mechanism elucidation by the MO method
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The cathodic reduction of sulfonium salts in acetonirile under the presence and absence of benzaldehyde were carried out and compared with the results of the base method. Under the presence of benzaldehyde, the electrochemical reduction gave epoxides as a
- Okazaki, Yuichi,Ando, Fumio,Koketsu, Jugo
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Read Online
- Tin(II)-mediated allylation. Asymmetric induction with a chiral tin(II) alkoxide
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In a study of tin-mediated allylation some tin(II) species including tin(II) halides, amides, acetonates, and alkoxides, have been shown to undergo oxidation of allyl halide in the presence of benzaldehyde to give the corresponding homoallyl alcohol.The first preparation of a chiral tin(II) alkoxide, tin(II) diethyltartrate is described; its 119Sn NMR spectrum exhibits two signals at high field, consistent with a trans dimer structure.This new reagent undergoes oxidative addition of 1,3-chloroiodopropene in the presence of benzaldehyde to give an optically active phenylvinyloxirane; this represents the first enantioselective preparation of cis- and trans-vinyloxiranes from aldehydes.
- Auge, Jacques,Bourleaux, Guy
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Read Online
- Novel reaction course of thiiranes to vinyloxiranes: Reaction of benzyne with thiiranes and aldehydes
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Reaction of 2 molar amount of 2-(trimethylsilyl)phenyl triflate with thiiranes and aldehydes in the presence of CsF afforded vinyloxiranes in one-pot operation. Reaction of benzyne with thiiranes gave the corresponding alkenyl phenyl sulfides, which furth
- Okuma, Kentaro,Qu, Yuxuan,Nagahora, Noriyoshi
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p. 1294 - 1300
(2021/07/19)
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- Synthesis of Epoxides from Alkyl Bromides and Alcohols with in Situ Generation of Dimethyl Sulfonium Ylide in DMSO Oxidations
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Direct conversion of the readily available alkyl bromides and alcohols to value-added epoxides using dimethyl sulfoxide (DMSO) under mild reaction conditions has been developed. Benzyl and allyl bromides, and activated and unactivated alcohols all proceeded smoothly to give epoxides in high to excellent yield. Dimethyl sulfide, generated by DMSO oxidations, was in situ elaborated to form the substituted dimethyl sulfonium ylide species that participates in the Corey-Chaykovsky epoxidation in a domino and one-pot fashion, respectively.
- Zhang, Zhi-Wei,Li, Hai-Bo,Li, Jin,Wang, Cui-Cui,Feng, Juan,Yang, Yi-Hua,Liu, Shouxin
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p. 537 - 547
(2020/01/02)
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- A One-Pot Reaction toward the Diastereoselective Synthesis of Substituted Morpholines
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The diastereoselective synthesis of various substituted morpholines has been achieved from vinyloxiranes and amino-alcohols under sequential Pd(0)-catalyzed Tsuji-Trost/Fe(III)-catalyzed heterocyclization. Using the same strategy, 2,6-, 2,5-, and 2,3-disubstituted as well as 2,5,6- and 2,3,5-trisubstituted morpholines were obtained in good to excellent yields and diastereoselectivities.
- Aubineau, Thomas,Cossy, Janine
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supporting information
p. 7419 - 7423
(2018/12/11)
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- A new protocol for the in situ generation of aromatic, heteroaromatic, and unsaturated diazo compounds and its application in catalytic and asymmetric epoxidation of carbonyl compounds. Extensive studies to map out scope and limitations, and rationalization of diastereo- and enantioselectivities
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A variety of metalated tosylhydrazone salts derived from benzaldehyde have been prepared and were reacted with benzaldehyde in the presence of tetrahydrothiophene (THT) (20 mol %) and Rh2(OAc)4 (1 mol %) to give stilbene oxide. Of the lithium, sodium, and potassium salts tested, the sodium salt was found to give the highest yield and selectivity. This study was extended to a wide variety of aromatic, heteroaromatic, aliphatic, α,β-unsaturated, and acetylenic aldehydes and to ketones. On the whole, high yields of epoxides with moderate to very high diastereoselectivities were observed. A broad range of tosylhydrazone salts derived from aromatic, heteroaromatic, and α,β-unsaturated rated aldehydes was also examined using the same protocol in reactions with benzaldehyde, and again, good yields and high diastereoselectivities were observed in most cases. Thus, a general process for the in situ generation of diazo compounds from tosylhydrazone sodium salts has been established and applied in sulfur-ylide mediated epoxidation reactions. The chiral, camphor-derived, [2.2.1] bicyclic sulfide 7 was employed (at 5-20 mol % loading) to render the above processes asymmetric with a range of carbonyl compounds and tosylhydrazone sodium salts. Benzaldehyde tosylhydrazone sodium salt gave enantioselectivities of 91 ± 3% ee and high levels of diastereoselectivity with a range of aldehydes. However, tosylhydrazone salts derived from a range of carbonyl compounds gave more variable selectivities. Although those salts derived from electron-rich or neutral aldehydes gave high enantioselectivities, those derived from electron-deficient or hindered aromatic aldehydes gave somewhat reduced enantioselectivities. Using α,β-unsaturated hydrazones, chiral sulfide 7 gave epoxides with high diastereoselectivities, but only moderate yields were achieved (12-56%) with varying degrees of enantioselectivity. A study of solvent effects showed that, while the impact on enantioselectivity was small, the efficiency of diazo compound generation was influenced, and CH3CN and 1,4-dioxane emerged as the optimum solvents. A general rationalization of the factors that influence both relative and absolute stereochemistry for all of the different substrates is provided. Reversibility in formation of the betaine intermediate is an important issue in the control of diastereoselectivity. Hence, where low diastereocontrol was observed, the results have been rationalized in terms of the factors that contribute to the reduced reversion of the syn betaine back to the original starting materials. The enantioselectivity is governed by ylide conformation, facial selectivity in the ylide reaction, and, again, the degree of reversibility in betaine formation. From experimental evidence and calculations, it has been shown that sulfide 7 gives almost complete control of facial selectivity, and, hence, it is the ylide conformation and degree of reversibility that are responsible for the enantioselectivity observed. A simple test has been developed to ascertain whether the reduced enantioselectivity observed in particular cases is due to poor control in ylide conformation or due to partial reversibility in the formation of the betaine.
- Aggarwal, Varinder K.,Alonso, Emma,Bae, Imhyuck,Hynd, George,Lydon, Kevin M.,Palmer, Matthew J.,Patel, Mamta,Porcelloni, Marina,Richardson, Jeffery,Stenson, Rachel A.,Studley, John R.,Vasse, Jean-Luc,Winn, Caroline L.
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p. 10926 - 10940
(2007/10/03)
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- Preparation of γ-heterosubstituted allylindium and diindium reagents and their reactions with carbonyl compounds
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Various γ-heteroatom-substituted allylindium reagents were prepared, and their reactions with carbonyl compounds were examined. The reaction of 1,3-dibromopropene with metallic indium gave two types of organoindium species, γ-bromoallylindium and allylic
- Hirashita, Tsunehisa,Kamei, Toshiya,Horie, Tomoaki,Yamamura, Hatsuo,Kawai, Masao,Araki, Shuki
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p. 172 - 177
(2007/10/03)
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- Simple synthetic method of allyl- and vinyl-epoxides by allylation of carbonyl groups with allylic tins catalyzed by PbI2-HMPA
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Allyl epoxides were prepared by the chemoseletive allylation at the carbonyl groups of a-bromo ketones with allylic tin, where PbI2-HMPA effected as a chemoselective catalyst. Moreover, vinyl epoxides were obtained in one pot procedure by the P
- Shibata, Ikuya,Fukuoka, Shoji,Baba, Akio
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p. 533 - 534
(2007/10/03)
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- Diastereo- and enantioselective synthesis of syn-α-vinylchlorohydrins and cis-vinylepoxides
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A new method to generate chiral syn-vinylchlorohydrins and cis-vinyloxiranes is reported. Reaction of (α-haloallyl)lithiums with methoxy-9-BBN or Ipc2BOMe followed by treatment with BF3·OEt2 leads to (Z)-(γ-haloallyl)boranes which react with aldehydes to yield cis-vinylepoxides (de ≥ 90%) upon oxidative workup. Alternatively, addition of ethanolamine to the allylboration product yields syn-α-halohydrins (de ≥ 90%) that are also easily cyclized to cis-vinylepoxides. Extension of this protocol using [(Z)-γ-chloroallyl]BIpc2 leads to chiral syn-α-chlorohydrins and cis-vinylepoxides in high de (≥90%) and ee (90-99%). Enantioselectivity of reactions of chiral (Z)-(γ-chloroallyl)boranes with aldehydes are more sensitive to reaction conditions than enantioselectivity of reactions of other α-or γ-substituted allylboranes. The effects of proportion of BP3·OEt2 and the relative efficacies of LiNR2 bases on diastereo- and enantioselectivity of the chloroallylation are reported.
- Hu, Shaojing,Jayaraman, Seetharaman,Oehlschlager, Allan C.
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p. 7513 - 7520
(2007/10/03)
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- A novel catalytic cycle for the synthesis-of epoxides using sulfur ylides: Application to base sensitive aldehydes
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Epoxidation of base sensitive aldehydes can be achieved by a new catalytic cycle which requires the slow addition of a diazocompound to a solution of an aldehyde containing catalytic quantities of a sulfide and catalytic quantities of rhodium acetate.
- Aggarwal, Varinder K.,Abdel-Rahman, Hesham,Jones, Ray V.H.,Standen, Mike C.H.
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p. 1731 - 1732
(2007/10/02)
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- Reactions of α-haloallyllithium derivatives with carbon, silicon, tin or boron halides and carbonyl compounds
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A series of allylic halides have been converted into their α-carbanions with strong lithium bases, using different techniques.These have been compared in their reaction with various electrophiles leading to functionally substituted allyl derivatives.The influence of the counterion on the regio- and stereoselectivity has been investigated. allylic halides / α-halocarbanions / allylsilanes / allyltin derivatives / α-chlorohydrins / vinylepoxides / diastereoselectivity
- Julia, Marc,Verpeaux, Jean-Noel,Zahneisen, Thomas
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p. 539 - 554
(2007/10/02)
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- Chloroallyl Anion: Highly Regio- and Diastereoselective α-Addition of Chloroallyl Zinc Reagent to Carbonyl Compounds
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The chloroallyl zinc reagent generated insitu by deprotonation of allyl chloride in the presence of lithium diisopropylamide and zinc chloride undergoes highly regio- and diastereoselective α-addition to carbonyl compounds to give syn chlorohydrins which
- Mallaiah, K.,Satyanarayana, J.,Ila, H.,Junjappa, H.
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p. 3145 - 3148
(2007/10/02)
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- A FIRST EXAMPLE OF CATALYTIC YLIDE EPOXIDATION REACTION: FACILE SYNTHESIS OF VINYL EPOXIDES FROM ALDEHYDES CATALYZED BY DIISOBUTYL TELLURIDE
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In the presence of cesium carbonate, a variety of aldehydes can be epoxidized directly with allyl bromide at 50 deg C under solid-liquid phase transfer condition by use of a catalytic amount of diisobutyl telluride to afford vinyl epoxides in good yields
- Zhou, Zhang-Lin,Shi, Li-Lan,Huang, Yao-Zeng
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p. 7657 - 7660
(2007/10/02)
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- FACILE PREPARATION OF γ-CHLORO-SUBSTITUTED ALLYLMETALLIC REAGENTS AND THEIR REACTIONS. STEREOSELECTIVE ACCESS TO CIS-VINYLOXIRANES
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The title compounds are readily prepared from metallated allyl chloride and organotin chloride or organoaluminum chloride.After treatment with a base, they react with aldehydes in highly regio- and diastereo-selective modes, giving cis-vinyloxiranes selectively.Keywords -- lithiated allyl chloride; Z-γ-chloroallyltrimethyltin; γ-chloroallyldiethylaluminum; stereoselective synthesis; syn-chlorohydrin; cis-vinyloxirane
- Hosomi, Akira,Kohra, Shinya,Tominaga, Yoshinori,Ando, Masamoto,Sakurai, Hideki
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p. 3058 - 3061
(2007/10/02)
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- Selective Condensation of titanium Reagent with Carbonyl Compounds
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titanium reagent generated easily from allyl ethyl sulfides condensed with aldehydes to give erythro-β-hydroxy sulfides in highly regio- and stereoselective manner.In contrast, crotyl ethyl sulfide reacted with aldehydes affording δ-hydroxy vinyl sulfide exclusively.The substitution pattern of the starting sulfide can have a pronounced effect on the selectivity in this condensation reaction, erythro-β-Hydroxy sulfide obtained was transfromed stereoselectively to the trans-vinyloxirane or 1,3-alkadiene.
- Furuta, Kyoji,Ikeda, Yoshihiko,Meguriya, Noriyuki,Ikeda, Nobuo,Yamamoto, Hisashi
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p. 2781 - 2790
(2007/10/02)
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- Oxyanionic Substituent Effect on the C-H Insertion of Carbenes. Reaction of Alkoxides with Dichlorocarbene and Chlorophenylcarbene
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The lithium alkoxides of benzylic, allylic, and simple alkyl alcohols were allowed to react with chloroform in the presence of t-BuOLi in THF-hexane to give, in 32-91percent yields, dichloromethylcarbinols, which were produced by the insertion of dichlorocarbene into the α C-H bond of alkoxides but not by the Wittig rearrangement of carbanions of alkyl dichloromethyl ethers.The enhanced reactivity toward dichlorocarbene of the α C-H bond of alkoxides was clearly demonstrated by the high selectivity of the insertion.The potassium alkoxides of a series of analogous alcohols reacted analogously with benzal chloride in the presence of t-BuOK in THF to give the corresponding substituted oxiranes (16-79percent); e.g., the reaction of potassium benzyl oxide gave 2,3-diphenyloxirane (79percent) as a mixture of stereoisomers (trans:cis = 1.0).With 2-phenethoxide, n-octyl oxide, or 2-methoxyethoxide, the corresponding dialkyl acetals of benzaldehyde were also formed in 9, 6, and 6percent yield, respectively, and their formation is explained in terms of nucleophilic attack of alkoxide on chlorophenylcarbene.With trans-crotyl oxide or 2-phenetoxide, 1,3-diphenylpropan-1-one(33percent) and 1-phenylpent-3-en-1-one (6percent) were produced, respectively, as byproducts through the isomerization of the primary product oxiranes.Oxiranes were produced by the insertion of chlorophenylcarbene into the α C-H bond of alkoxides followed by the cyclization of the intermediate 1-substituted 2-chloro-2-phenethyl alkoxide.These reactions provide us with new preparative methods of synthetically useful dichloromethyl carbinols and oxiranes.
- Harada, Toshiro,Akiba, Eiji,Oku, Akira
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p. 2771 - 2776
(2007/10/02)
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- A SIMPLE, STEREOSELECTIVE, ROOM-TEMPERATURE SYNTHESIS OF CIS VINYLOXIRANES AND TRANS 1-PHENYL-1,3-BUTADIENE
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The organotin reagent from 1-chloro-3-iodoprop-1-ene and SnCl2 in dimethylformamide reacted with aldehydes by its chlorine-substituted carbon atom.Treatment with NaOMe then gave cis vinyloxiranes with good stereoselectivity.Benzaldehyde and 1-bromo-3-iodo
- Auge, Jacques,David, Serge
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p. 4009 - 4012
(2007/10/02)
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- THE HIGHLY STEREOSELECTIVE SYNTHESIS OF CIS-VINYLOXIRANES
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In the presence of triethylaluminum, oxyallyl anions derived from 2-allyloxybenzimidazoles react with aldehydes in highly regio- and stereoselective manner to afford α-adducts in good yields.The adducts are stereospecifically converted to cis-vinyloxiranes in good yields.
- Yamaguchi, Masahiko,Mukaiyama, Teruaki
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p. 237 - 240
(2007/10/02)
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- ACTION DU CHLOROALLYLLITHIUM SUR LES ALDEHYDES ET LES CETONES: SYNTHESE EN UNE ETAPE D'ALCOOLS β-ETHYLENIQUES γ-CHLORES DE CONFIGURATION Z ET D'EPOXYDES α-ETHYLENIQUES BI- OU TRI-SUBSTITUES
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Chloroallyllithium readily reacts with aliphatic and aromatic aldehydes and ketones to produce, in a one-step reaction, Z-γ-chlorinated-β-ethylenic alcohols and bi- or tri-substituted epoxides.
- Doucoure, A.,Mauze, B.,Miginiac, L.
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p. 139 - 148
(2007/10/02)
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- Reaction of 3-Chloroallyltrimethylsilane with Acid Chloride and Exploitation of a New Regioselective Synthesis of αβ-Unsaturated Epoxide
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α-Chloro-βγ-unsaturated ketone (2) was synthetized from the reaction of 3-chloroallyltrimethylsilane (1) with acid chloride.The ketone was converted into αβ-unsaturated epoxide (3) regioselectively in good yield via reduction with NaBH4 or LiAlH4 followed
- Ochiai, Masahito,Fujita, Eiichi
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p. 4369 - 4372
(2007/10/02)
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