Cycloaddition reactions of phenylallene. Ring closure of the diradical intermediate involving the aromatic ring

1986 ◽  
Vol 51 (10) ◽  
pp. 1676-1680 ◽  
Author(s):  
Daniel J. Pasto ◽  
Shun Hua Yang
Keyword(s):  
Aromatic Ring ◽  
Ring Closure ◽  
Cycloaddition Reactions

scholarly journals Dihydroquinolines, Dihydronaphthyridines and Quinolones by Domino Reactions of Morita-Baylis-Hillman Acetates

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 890
Author(s):  
Joel K. Annor-Gyamfi ◽  
Ebenezer Ametsetor ◽  
Kevin Meraz ◽  
Richard A. Bunce
Keyword(s):  
Aromatic Ring ◽  
Aromatic Amines ◽  
Control Experiment ◽  
Ring Closure ◽  
Domino Reaction ◽  
Side Chain ◽  
Initial Reaction ◽  
Dual Reactivity ◽  
Michael Acceptor ◽  
Nitrogen Nucleophile

An efficient synthetic route to highly substituted dihydroquinolines and dihydronaphthyridines has been developed using a domino reaction of Morita-Baylis-Hillman (MBH) acetates with primary aliphatic and aromatic amines in DMF at 50–90 °C. The MBH substrates incorporate a side chain acetate positioned adjacent to an acrylate or acrylonitrile aza-Michael acceptor as well as an aromatic ring activated toward SNAr ring closure. A control experiment established that the initial reaction was an SN2′-type displacement of the side chain acetate by the amine to generate the alkene product with the added nitrogen nucleophile positioned trans to the SNAr aromatic ring acceptor. Thus, equilibration of the initial alkene geometry is required prior to cyclization. A further double bond migration was observed for several reactions targeting dihydronaphthyridines from substrates with a side chain acrylonitrile moiety. MBH acetates incorporating a 2,5-difluorophenyl moiety were found to have dual reactivity in these annulations. In the absence of O2, the expected dihydroquinolines were formed, while in the presence of O2, quinolones were produced. All of the products were isolated in good to excellent yields (72–93%). Numerous cases (42) are reported, and mechanisms are discussed.

scholarly journals α-Halogenoacetamides: versatile and efficient tools for the synthesis of complex aza-heterocycles

2019 ◽  
Vol 17 (37) ◽  
pp. 8467-8485 ◽  
Author(s):  
Abderrahman El Bouakher ◽  
Arnaud Martel ◽  
Sébastien Comesse
Keyword(s):  
Ring Closure ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions

This review presents the use of α-alkyl- and α-alkoxy-halogenoacetamides as powerful partners for domino and 1,3-dipolar cycloaddition reactions resulting in a ring closure.

scholarly journals Photochemical and thermal intramolecular 1,3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

2011 ◽  
Vol 7 ◽  
pp. 1663-1670 ◽  
Author(s):  
Kristina Butković ◽  
Željko Marinić ◽  
Krešimir Molčanov ◽  
Biserka Kojić-Prodić ◽  
Marija Šindler-Kulyk
Keyword(s):  
Acetic Acid ◽  
Photochemical Reactions ◽  
Acid Anhydride ◽  
Ring Closure ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Thermal Reactions

New trans- and cis-o-stilbene-methylene-sydnones 3a,b were synthesized by transforming the trans- and cis-o-aminomethylstilbene derivative, obtained by reduction of corresponding o-cyano derivatives, into glycine ester derivatives (43 and 31% yield) followed by hydrolysis (90 and 96% yield), nitrosation and ring closure with acetic acid anhydride (30 and 40% yield). The products were submitted to photochemical and thermal intramolecular [3 + 2] cycloadditions to afford diverse heteropolycyclic compounds. Photochemical reactions afforded cis-3-(4-methylphenyl)-3a,8-dihydro-3H-pyrazolo[5,1-a]isoindole (11, 12.5% yield) and trans-3-(4-methylphenyl)-3a,8-dihydro-3H-pyrazolo[5,1-a]isoindole (12, 5% yield). Thermal reactions afforded 3-(4-methylphenyl)-3,3a,8,8a-tetrahydroindeno[2,1-c]pyrazole (14, 50% yield) and 11-(4-methylphenyl)-9,10-diazatricyclo[7.2.1.02,7]dodeca-2,4,6,10-tetraene (15, 22% yield).

Synthesis of 5-Aryl- 1,4-benzoxazepine and 6-phenyl-2H-1,5-benzoxazocine derivatives

1984 ◽  
Vol 37 (1) ◽  
pp. 129 ◽  
Author(s):  
JB Bremner ◽  
EJ Browne ◽  
IWK Gunawardana
Keyword(s):  
Aromatic Ring ◽  
Sodium Tetrahydroborate ◽  
Phosphorus Oxychloride ◽  
Ring Expansion ◽  
Ring Closure ◽  
Dilute Solution ◽  
Type Reaction ◽  
Chlorine Substituent

Four 5-aryl-2,3-dihydro-1,4-benzoxazepines (5a-d), with electron-releasing substituents, were prepared by a Bischler-Napieralski-type reaction of N-(2-aryloxyethyl)benzamides with phosphorus oxychloride in butanenitrile or ethanenitrile. Analogous 2,3-dihydro-1,4-benzoxazepines (12a, b), with hydrogen only or a chlorine substituent in the fused aromatic ring, were prepared by C-N ring-closure reactions. Cyclization of a dilute solution of N-[3-(3-methoxyphenoxy)propyl]benzamide (21) with phosphorus oxychloride in ethanenitrile gave a 40% yield of 9-methoxy-6-phenyl-3,4-dihydro- 2H-1,5-benzoxazocine (22). The seven- and eight-membered cyclic imines were converted into their methiodide salts (6a-d), (15a,b) and (24). These were reduced with sodium tetrahydroborate to yield the 5-aryl-4-methyl-2,3,4,5-tetrahydro-1,4-benzoxazepines (7a-d) and (l6a,b), and the 9-methoxy- 5-methyl-6-phenyl-3,4,5,6-tetrahydro-2H-1,5-benzoxazocine (25). These products were prepared for use as starting materials in ring-expansion reactions through the Meisenheimer rearrangement.

scholarly journals Naphthalenes and Quinolines by Domino Reactions of Morita–Baylis–Hillman Acetates

Molecules ◽  
2020 ◽  
Vol 25 (21) ◽  
pp. 5168
Author(s):  
Joel K. Annor-Gyamfi ◽  
Ebenezer Ametsetor ◽  
Kevin Meraz ◽  
Richard A. Bunce
Keyword(s):  
Aromatic Ring ◽  
Control Experiment ◽  
Ring Closure ◽  
Side Chain ◽  
Initial Reaction ◽  
Domino Reactions ◽  
Initial Product ◽  
Michael Acceptor ◽  
Active Methylene Compounds ◽  
Active Methylene

An efficient synthetic route to highly functionalized naphthalenes and quinolines has been developed using domino reactions between Morita–Baylis–Hillman (MBH) acetates and active methylene compounds (AMCs) promoted by anhydrous K2CO3 in dry N,N-dimethylformamide (DMF) at 23 °C. The substrates incorporate allylic acetates positioned adjacent to a Michael acceptor as well as an aromatic ring activated toward a SNAr ring closure. A control experiment indicated that the initial reaction was an SN2’-type displacement of a side chain acetoxy by the AMC anion to afford the alkene product bearing the added nucleophile trans to the SNAr aromatic ring acceptor. Thus, equilibration of the alkene geometry of the initial product was required prior to cyclization. Products were isolated in good to excellent yields. Numerous cases (24) are reported, and several mechanistic possibilities are discussed.

scholarly journals Competitive 1,3-Dipolar Cycloaddition Reactions of an Azomethine Ylide with Aromatic and Carbonyl Groups of Nitro-Substituted Isatoic Anhydrides

2018 ◽  
Vol 71 (9) ◽  
pp. 690 ◽  
Author(s):  
Asha M. D'Souza ◽  
Daniel J. Rivinoja ◽  
Roger J. Mulder ◽  
Jonathan M. White ◽  
Adam G. Meyer ◽  
...  
Keyword(s):  
Carbonyl Group ◽  
Aromatic Ring ◽  
Addition Reaction ◽  
Cycloaddition Reaction ◽  
Azomethine Ylide ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Carbonyl Groups ◽  
Isatoic Anhydride

A study of the reactivity of a non-stabilised azomethine ylide, derived from N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine, with nitro-substituted isatoic anhydrides was undertaken. N-Methyl-4-nitroisatoic anhydride underwent a 1,3-dipolar cycloaddition reaction exclusively at the isatoic anhydride C1-carbonyl group, followed by decarboxylative rearrangement to yield a benzo-1,3-diazepin-5-one derivative. In contrast, N-methyl-5-nitroisatoic anhydride underwent competing cycloaddition processes to the isatoic anhydride C1-carbonyl group and to the nitro-substituted aromatic ring. The dearomative addition reaction resulted in the formation of novel tetracyclic products.

Ditopic thiacyclophanes containing the S(CH2)2X(CH2)2S (X = O, S) linkage. Synthesis and structures of 2,5,8,17,20,23-hexathia[9](1,2)[9](4,5)cyclophane and 5,20-dioxa-2,8,17,23-tetrathia[9](1,3)[9](4,6)-2,5-bis(ethoxy)cyclophane

1994 ◽  
Vol 72 (7) ◽  
pp. 1728-1734 ◽  
Author(s):  
Stephen J. Loeb ◽  
George K.H. Shimizu
Keyword(s):  
Crystal Structures ◽  
Aromatic Ring ◽  
Ring Closure ◽  
Structural Variations ◽  
Triclinic Space Group ◽  
Space Group ◽  
Target Molecule ◽  
Double Ring ◽  
Linkage Synthesis

The Cs+/DMF mediated reactions of 1,2,4,5-tetra(bromomethyl)benzene and 1,2,4,5-tetra(bromomethyl)3,6-bis(ethoxy)benzene with dithiols HSCH2CH2XCH2CH2SH (X = S,O) were explored in order in order to ascertain the effect of structural variations on the regioselectivity of double ring-closure. Although a structure with bis(ortho) geometry was the target molecule, the major products are those with a bis(meta) structure. Two crystal structures, one with a bis(ortho) structure, 2,5,8,17,20,23-hexathia[9](1,2)[9](4,5)cyclophane, 1, and one with a bis(meta) structure, 5,20-dioxa-2,8,17,23-tetrathia[9](1,3)[9](4,6)−2,5-bis(ethoxy)cyclophane, 7, are reported. 1 crystallized in the triclinic space group [Formula: see text] with a = 8.583(3), b = 11.806(3), c = 5.448(2) Å, α = 97.18(2), β = 107.18(2), γ = 99.40(2)°, V = 511.6(6) Å3, and Z = 1. The structure refined to R = 6.48% and Rw = 7.13% for 1020 reflections with Fo2 > 3σ(Fo2). 7 crystallized in the triclinic space group [Formula: see text] with a = 9.568(2), b = 9.577(2), c = 8.312(2) Å, α = 113.53(2), β = 94.58(2), γ = 114.94(2)°, V = 604.3(7) Å3 and Z = 1. The structure refined to R = 3.86% and Rw = 4.20% for 1129 reflections with Fo2 > 3σ(Fo2). Both compounds sit on a crystallographic centre of symmetry and have the thioether linkages oriented on opposite sides of the central aromatic ring.

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