Photochemical Reactions of Benzo[b]Thiophene-2,3-Diones with 2,3-Dimethylbut-2-Ene

Abstract

Photochemical reactions of benzo[b]thiophene-2,3-diones with 2,3-dimethylbut-2-ene gave dioxene derivatives in excellent yields.     

Photocycloaddition of 2-Oxopyran-3-carbonitriles to 2,3-Dimethylbut-2-ene

On acetone-sensitized irradiation in the presence of 2,3-dimethylbut-2-ene, α-cyano-α,β-unsaturated δ-lactone 5 is converted both to cyclopentapyrans resulting from stepwise addition of the alkene to the olefinic C(β)- and the nitrile C-atom of triplet excited 5 , and cyclobutapyranes, i.e., [2+2] cycloadducts. Similarly, direct irradiation of 1-benzopyran-3-carbonitrile 6 in the presence of the same alkene affords cyclobutabenzopyran 13 and cyclopentabenzopyran 14 , the latter resulting from an upper excited triplet state of 6 .     

Novel Photocycloaddition Reactions of N-Methyl-2, 3-naphthalenedicarboximide with Phenylacetylene

UV irradiation of N-methyl-2,3-naphthalenedicarboximide with phenylacetylene in benzene solution afforded a novel hexacyclic adduct 2 confirmed unambiguously by single crystal X-ray diffraction.     

The Regiospecific Synthesis of Some New 3,5‐Disubstituted Isoxazoles

The compounds with isoxazole moiety have many pharmacological, biological and industrial applications, specifically their antiviral activity. In this research work, seven new compounds of 3,5‐disubstituted isoxazoles were synthesized. Propargyl alcohol ( 1 ) reacted with benzoyl chloride to give propargylphenylcarboxylate ( 2 ). Then, the aldehydes ( 3a‐3g ) were converted to the related oximes ( 4a‐4g ) and nitrileoxides in situ by NaOCl, consequently. Reaction of compound 2 with nitrileoxides in a [3+2] cycloaddition reaction gave regiospecifically isoxazoles ( 5a‐5g ). ¹H NMR, ¹³C NMR, FT‐IR, and elemental analyses confirmed the structure of the synthesized compounds.     

Copper(I)‐Catalyzed Asymmetric [3+2]‐Cycloaddition of α‐Substituted Iminoesters with α‐Trifluoromethyl α,β‐Unsaturated Esters

Reported herein is an example of highly regio‐, diastereo‐ and enantioselective Cu(I)‐catalyzed intermolecular [3+2] cycloaddition reaction of α‐substituted iminoesters with α‐trifluoromethyl α,β‐unsaturated esters. This novel strategy provided a facile access to pyrrolidines with two skipped (aza)quaternary stereocenters including a CF₃ all‐carbon quaternary stereocenter. A broad substrate scope was observed and high yields (up to 94%) with excellent diastereoselectivity (up to >20 : 1 d.r.) and enantioselectivity (up to 98% ee) were obtained.     

Diastereo- and enantioselective palladium-catalyzed dearomative [4+2] cycloaddition of 3-nitroindoles

A Pd-catalyzed asymmetric decarboxylative [4+2] cycloaddition of 3-nitroindoles and vinyl benzoxazinanones is developed through a dearomatization approach. The reaction provides an efficient protocol for constructing a series of chiral tetrahydro-5H-indolo[2,3-b]quinolines in high yields and with excellent diastereo- and enantioselectivities.     

Reactivity of allenoates toward aziridines: [3+2] and formal [3+2] cycloadditions

The reactivity of buta-2,3-dienoates toward aziridines is reported. Allenoates react as 2π-component in the [3+2] cycloaddition with the azomethine ylide generated from cis-1-benzyl-2-benzoyl-3-phenylaziridine affording 4-methylenepyrrolidines in a site-, regio-, and stereoselective fashion. Under conventional thermolysis, cis- and trans-2-benzoyl-1-cyclohexyl-3-phenylaziridines showed a different reactivity. These aziridines participate in formal [3+2] cycloadditions with allenes via C-N bond cleavage of the three-membered ring leading to functionalized pyrroles.     

Synthesis and properties of azoles and their derivatives. 57. Unexpected results of 3-nitropropene-1 [2+3] cycloaddition to C,C,N-triphenylnitrone

[2+3] Cycloaddition of 3-nitropropene-1 with C,C,N-triphenylnitrone leads to a mixture of 5-nitromethyl-2,3,3-triphenylisoxazolidine and 5-methyl-4-nitro-2,3,3-triphenylisoxazolidine. The results obtained can be explained assuming that 3-nitropropene-1 isomerizes to 1-nitropropene-1 under reaction conditions. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1545–1548, October, 2006.     

[3+2] Cycloaddition of Dimethyl Acetylenedicarboxylate, Methyl Acrylate, and Ethyl Acrylate to 4,5-Dihydro-5-methyl-3H-spiro[benz-2-azepine-3,1'-cyclohexane] N-Oxide

The cycloaddition of methyl acrylate and ethyl acrylate to 4,5-dihydro-5-methyl-3H-spiro[benz-2-azepine-3,1'-cyclohexane] N-oxide proceeds without either regiospecificity or stereospecificity. Eight geometrical isomers of spiro[isoxazolidino[3,2-a]benz-2-azepine-5,1'-cyclohexane] were formed, of which several were isolated as pure samples. The cycloaddition of dimethyl acetylenedicarboxylate proceeds stereoselectively, leading to spiro[isoxazolino[3,2-a]benz-2-azepine-5,1'-cyclohexane] with cis arrangement of the protons at C₍₇₎ and C_(11b).     

基于CaBa_2(BO_3)_2中的Ce~(3+)→Tb~(3+)能量传递及光谱特性

采用高温固相法合成了Ce3+,Tb3+掺杂激活的CaBa2(BO3)2荧光粉,并对其发光特性进行了研究。观察到CaBa2(BO3)2中Ce3+对Tb3+发光的敏化现象。在367 nm紫外光激发下,单掺Tb3+时CaBa2(BO3)2不发光。当Ce3+和Tb3+共掺时,出现Tb3+的发射峰,样品发绿光,表明Ce3+对Tb3+的发光有很强的敏化作用。根据Forster-Dexter理论,分析Ce3+和Tb3+的能量传递过程,还证明在CaBa2(BO3)2:Ce3+,Tb3+中Ce3+对Tb3+的能量传递属于共振能量传递。     

Solid-state[2+2] Photocycloaddition Reaction of Zinc(II) Complex Based on Quaternized 1,2-Bis(4'-pyridyl) ethylene

Aphotoactive metal-organic complex[Zn₂(BCbpe)₂(p-DBC)₂]∙     

可重复使用CuO纳米粒子催化微波辅助的腈和NaN3环加成反应 合成5-取代1H-四唑类

将可重复使用的CuO纳米粒子成功用于催化微波辅助的腈和NaN3[3+2]环加成反应高效合成5-取代1H-四唑类化合物.该法突出特点为成本低、合成快、稳定性高、可重复使用、反应条件温和、无需任何添加物、官能团兼容性好和产率高.这种环境友好的微波辅助纳米粒子催化合成策略可望替代现有的涉及常规路易斯酸催化剂方法,以及作为一种简易的合成特殊化合物的方法.     

Synthesis and Structure Elucidation of Novel Spirooxindole Linked to Ferrocene and Triazole Systems via [3 + 2] Cycloaddition Reaction

In the present work, a novel heterocyclic hybrid of a spirooxindole system was synthesized via the attachment of ferrocene and triazole motifs into an azomethine ylide by [3 + 2] cycloaddition reaction protocol. The X-ray structure of the heterocyclic hybrid (1″R,2″S,3R)-2″-(1-(3-chloro-4-fluorophenyl)-5-methyl-1H-1,2,3-triazole-4-carbonyl)-5-methyl-1″-(ferrocin-2-yl)-1″,2″,5″,6″,7″,7a″-hexahydrospiro[indoline-3,3″-pyrrolizin]-2-one revealed very well the expected structure, by using different analytical tools (FTIR and NMR spectroscopy). It crystallized in the triclinic-crystal system and the P-1-space group. The unit cell parameters are a = 9.1442(2) Å, b = 12.0872(3) Å, c = 14.1223(4) Å, α = 102.1700(10)°, β = 97.4190(10)°, γ = 99.1600(10)°, and V = 1484.81(7) ų. There are two molecules per unit cell and one formula unit per asymmetric unit. Hirshfeld analysis was used to study the molecular packing of the heterocyclic hybrid. H···H (50.8%), H···C (14.2%), Cl···H (8.9%), O···H (7.3%), and N···H (5.1%) are the most dominant intermolecular contacts in the crystal structure. O···H, N···H, H···C, F···H, F···C, and O···O are the only contacts that have the characteristic features of short and significant interactions. AIM study indicated predominant covalent characters for the Fe–C interactions. Also, the electron density (ρ(r)) at the bond critical point correlated inversely with the Fe–C distances.     

Rh(I)-catalyzed intramolecular hetero-[4+2] cycloaddition of ω-alkynyl-vinyl oximes

Cationic rhodium(I) catalyst derived from [RhCl(cod)]₂ and AgSbF₆ in hexafluoroisopropanol (HFIP) efficiently catalyzed the formation of bicyclic pyridine derivatives by intramolecular hetero-[4+2] cycloadditions of ω-alkynyl-vinyl oximes.     

Imidazolidin-4-ones via (3+2) cycloadditions of aza-oxyallyl cations onto (E)-N-arylideneanilines

In the course of our studies on the chemistry of oxyallyl species we uncovered a new (3+2) cycloaddition of aza-oxyallyl systems, generated in situ from N-benzyloxy-2-chloroamides in the presence of NEt₃, onto N-arylimines yielding imidazolidin-4-ones in moderate to good yields. The cycloadditions are regioselective. Computational modeling using DFT at the M062x/6-311+G⁷ level is in support the observed regioselectivities. Although the path to the trans imidazolin-4-one is favored, the cis product is preferred by almost 8?kcal/mol and could be formed by base-catalyzed epimerization. All products were isolated by chromatography and characterized by means of their FTIR, NMR and HRMS data.     

Direct,enantioselective synthesis of pyrroloindolines and indolines from simple indole derivatives

The (R)-BINOL·SnCl₄-catalyzed formal (3+2) cycloaddition between 3-substituted indoles and benzyl 2-trifluoroacetamidoacrylate is a direct, enantioselective method to prepare pyrroloindolines from simple starting materials. However, under the originally disclosed conditions, the pyrroloindolines are formed as mixtures of diastereomers, typically in the range of 3:1 to 5:1 favoring the exo-product. The poor diastereoselectivity detracts from the synthetic utility of the reaction. We report here that use of methyl 2-trifluoroacetamidoacrylate in conjunction with (R)-3,3′-dichloro-BINOL·SnCl₄ provides the corresponding pyrroloindolines with improved diastereoselectivity (typically ≥10:1). Guided by mechanistic studies, a one-flask synthesis of enantioenriched indolines by in situ reduction of a persistent iminium ion is also described.     

Synthesis of psudoheliotridane via formal [3+2] annulation and ring-closing metathesis

Base-induced coupling/cyclization stepwise [3+2] annulation of α-sulfonylacetamide with (Z)-2-bromoacrylates yielded polysubstituted pyroglutamates with three contiguous chiral centers with trans-trans orientation in a one-pot synthesis. The pyrrolizidine skeleton was obtained via the ring-closing metathesis (RCM) method. This facile strategy was used to synthesize psudoheliotridane.     

Scope of the formal [3+2] cycloaddition for the synthesis of substituted 3-arylindanes and related compounds

We report the single step synthesis of several 3-arylindanes and related compounds via a formal [3+2] cycloaddition. A study of the influence of the aromatic ring substitution pattern on the reaction was carried out.     

Enantioselective,Decarboxylative (3+2)-Cycloaddition of Azomethine Ylides and Chromone-3-Carboxylic Acids

Herein, we describe the synthesis of a variety of chiral hybrid pyrrolidine-chromanone polycyclic derivatives. A convenient (3+2)-annulation of azomethine ylides with chromone-3-carboxylic acid realized under Brønsted base catalysis produced highly functionalized products in high yields with good stereoselectivities through asymmetric, intermolecular, and decarboxylative (3+2)-cyclization.