scholarly journals Absolute Asymmetric Synthesis Involving Chiral Symmetry Breaking in Diels–Alder Reaction

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 910 ◽  
Author(s):  
Naohiro Uemura ◽  
Seiya Toyoda ◽  
Waku Shimizu ◽  
Yasushi Yoshida ◽  
Takashi Mino ◽  
...  
Keyword(s):  
Main Product ◽  
Chiral Symmetry Breaking ◽  
Catalytic Amount ◽  
Alder Reaction ◽  
Enantiomeric Purity ◽  
Diels Alder ◽  
X Ray ◽  
Chiral Amplification ◽  
Diels Alder Reaction ◽  
Amplification Of Chirality

Efficient generation and amplification of chirality from prochiral substrates in the Diels–Alder reaction (DA reaction) followed by dynamic crystallization were achieved without using an external chiral source. Since the DA reaction of 2-methylfuran and various maleimides proceeds reversibly, an exo-adduct was obtained as the main product as the reaction proceeded. From single crystal X-ray structure analysis, it was found that five of ten exo-adducts gave conglomerates. When 2-methylfuran and various maleimides with a catalytic amount of TFA were reacted in a sealed tube, the exo-DA adducts were precipitated from the solution, while the reaction mixtures were continuously ground and stirred using glass beads. Deracemization occurred and chiral amplification was observed for four of the substrates. Each final enantiomeric purity was influenced by the crystal structure, and when enantiomers were included in the disorder, they reached an enantiomeric purity reflecting the ratio of the disorder. The final ee value of the 3,5-dimethylphenyl derivative after chiral amplification was 98% ee.

scholarly journals One-Pot and Metal-Free Synthesis of 3-Arylated 4-Nitrophenols via Polyfunctionalized Cyclohexanones from β-Nitrostyrenes

2020 ◽  
Author(s):  
Haruyasu Asahara ◽  
Minami Hiraishi ◽  
Nagatoshi Nishiwaki
Keyword(s):  
Dimethyl Sulfoxide ◽  
Catalytic Amount ◽  
Alder Reaction ◽  
Diels Alder ◽  
One Pot ◽  
Metal Free ◽  
Diels Alder Reaction ◽  
Thienyl Group ◽  
Danishefsky's Diene

β-Nitrostyrenes underwent the Diels-Alder reaction with Danishefsky’s diene to afford cyclohexenes together with the corresponding hydrolyzed products, 3-arylated 5-methoxy-4-nitrocyclohexanones. When the reaction was conducted in the presence of water, the cyclohexenes were efficiently hydrolyzed into cyclohexanones. Subsequent aromatization by heating the cyclohexanone with a catalytic amount of iodine in dimethyl sulfoxide gave 3-arylated 4-nitrophenols. The reaction of nitrostyrenes with Danishefsky’s diene could be conducted in one-pot to directly afford the corresponding nitrophenols. Moreover, a heteroaryl group such as a thienyl group could be introduced into the nitrophenol framework.

scholarly journals One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes

2020 ◽  
Vol 16 ◽  
pp. 1830-1836
Author(s):  
Haruyasu Asahara ◽  
Minami Hiraishi ◽  
Nagatoshi Nishiwaki
Keyword(s):  
Dimethyl Sulfoxide ◽  
Catalytic Amount ◽  
Alder Reaction ◽  
Diels Alder ◽  
One Pot ◽  
Metal Free ◽  
Diels Alder Reaction ◽  
Thienyl Group ◽  
Danishefsky's Diene

β-Nitrostyrenes underwent a Diels–Alder reaction with Danishefsky’s diene to afford cyclohexenes together with the corresponding hydrolyzed products, 3-arylated-5-methoxy-4-nitrocyclohexanones. When the reaction was conducted in the presence of water, the cyclohexenes were efficiently hydrolyzed into cyclohexanones. Subsequent aromatization by heating the cyclohexanone with a catalytic amount of iodine in dimethyl sulfoxide gave 3-arylated-4-nitrophenols. The reaction of nitrostyrenes with Danishefsky’s diene could be conducted in one pot to directly afford the corresponding nitrophenols. Moreover, a heteroaryl group, e.g., a thienyl group could be introduced into the nitrophenol framework.

scholarly journals Two-Carbon Ring Enlargement of Five-, Six-, and Seven-Membered 1-Aza-2-vinylcycloalk-2-enes with Dimethyl Acetylenedicarboxylate and Subsequent Thermal Isomerization Reactions

2006 ◽  
Vol 61 (4) ◽  
pp. 385-395 ◽  
Author(s):  
Gerhard Maas ◽  
Robert Reinhard ◽  
Hans-Georg Herz
Keyword(s):  
Elevated Temperatures ◽  
Alder Reaction ◽  
Thermal Isomerization ◽  
Diels Alder ◽  
Dimethyl Acetylenedicarboxylate ◽  
X Ray ◽  
Ring Enlargement ◽  
Diels Alder Reaction ◽  
Carbon Ring ◽  
Electrocyclic Reaction

2-Aminodienes, in which the enamine function is incorporated in a five-, six-, or seven-membered ring, react with dimethyl acetylenedicarboxylate in a sequence of [2+2] cycloaddition and electrocyclic ring-opening to form the two-carbon ring expanded unsaturated heterocycles, i.e., 3,4- dicarboxylate substituted 6,7-dihydro-1H-azepines 3, 8 and 21, 1,6,7,8-tetrahydroazocines 22, and 6,7,8,9-tetrahydro-1H-azonines 13. Similarly, 2-[(2-thienyl)ethynyl]-4,5,6,7-tetrahydro-1H-azepine 9 is converted into 2-[(2-thienyl)ethynyl]-6,7,8,9-1H-azonine-3,4-dicarboxylate 10 which was characterized by X-ray structure determination. The eight- and nine-membered azaheterocycles 22 and 13, which have not been isolated, undergo thermal isomerization at elevated temperatures. Thus, ring contraction by a 6π-electrocyclic reaction takes place for N-methyl substituted azonine 13, while the N-allyl moiety of azocines 22 engages in an intramolecular Diels-Alder reaction or a 1,7- electrocyclization reaction

The Asymmetric Diels–Alder Reaction by the Use of a Catalytic Amount of a Chiral Titanium Reagent

1986 ◽  
Vol 15 (11) ◽  
pp. 1967-1968 ◽  
Author(s):  
Koichi Narasaka ◽  
Masayuki Inoue ◽  
Tohru Yamada
Keyword(s):  
Catalytic Amount ◽  
Alder Reaction ◽  
Diels Alder ◽  
Diels Alder Reaction

ChemInform Abstract: Abnormal Diels-Alder Reaction of 5-Alkoxyoxazoles with Tetracyanoethylene and X-Ray Crystal Structure of an Adduct.

ChemInform ◽  
2010 ◽  
Vol 23 (44) ◽  
pp. no-no
Author(s):  
T. IBATA ◽  
Y. ISOGAMI ◽  
H. NAKAWA ◽  
H. TAMURA ◽  
H. SUGA ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Alder Reaction ◽  
Diels Alder ◽  
X Ray ◽  
Diels Alder Reaction

Molecular Topology of Linked Anthracenes: X-Ray Structure Analyses of Alkyl Di-9-anthryl-glycolates, 9-Anthryl 9-Anthrylmethyl Ethers and Their Photoisomers

1989 ◽  
Vol 42 (11) ◽  
pp. 1869 ◽  
Author(s):  
HD Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Single Crystal ◽  
Alder Reaction ◽  
Diels Alder ◽  
Molecular Structures ◽  
Molecular Topology ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diels Alder Reaction ◽  
Photochemical Isomerization ◽  
Spatial Demand

The molecular structures of ethyl di-9-anthrylglycolate (1) and methyl di-9-anthrylglycolate (2), as well as those of three isomerization products of (2), have been established by single-crystal X-ray diffraction studies. In both (1) and (2), the anthracenemoieties are characterized by marked deviations from planarity. The stereospecific course of the thermal and photochemical isomerization of (2) by Diels -Alder reaction is suggested to be governed by the spatial demand of the alkoxycarbonyl group. Base-catalysed isomerization of (2) by migration of 9-anthryl from carbon to oxygen is associated with steric relief.

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