On the photocycloaddition of dimethyl acetylenedicarboxylate to benzo(b)thiophene

Ditto, Steven R.; Davis, Paul D.; Neckers, Douglas C.

doi:10.1016/s0040-4039(01)90144-3

Cited by 16 publications

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“…The absorption spectrum of 7a in ethanol (Figure ) exhibits a broad structureless absorption band around 300−350 nm. This band is similar to the charge-transfer absorption band as observed in the unrearranged photoproduct of 1 and benzo[ b ]thiophene 1 Absorption spectrum of 2 , 6a , and 7a in ethanol.…”

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“…The photochemical reaction of thiophene and dimethyl acetylenedicarboxylate ( 1 ) affords a [4π + 2π] Diels−Alder adduct that undergoes instant extrusion of sulfur yielding dimethyl phthalate as the sole reaction product . Benzo[ b ]thiophene (BT) undergoes cycloaddition reactions with 1 , methyl propiolate, and methyl phenylpropiolate affording adducts that differ from the expected simple [2π + 2π] photoadduct. , The primary adduct of 1 to BT undergoes a secondary photorearrangement under the reaction conditions . Interestingly, this rearranged photoadduct is thermally unstable and yields naphthalene 1,2-dimethyl carboxylate upon pyrolysis …”

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Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene^,¹

et al. 2003

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The photochemical [2pi +2pi] cycloaddition of dimethyl acetylenedicarboxylate to benzo[1,2-b:4,5-b']dithiophene has been used to synthesize substituted cyclobuta[b]thieno[2,3-f][1]benzothiophene. The first [2pi + 2pi] photocycloaddition reaction of a series of butadiynes to benzodithiophene is reported to yield regioselective and acetylene-substituted cyclobutene derivatives containing an aromatic thiophene moiety.

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Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene^,¹

et al. 2003

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“…It is also important to note that, due to the cyclic nature of benzothiophene, the photoinduced cis–trans isomerization that is possible in acyclic olefins, around the C2–C3 bond, can be ruled out due to the connectivity of the double bond (within the aromatic ring). Furthermore, we used the S , S -dioxo derivatives of benzothiophene given their more efficient photoreactivity (the photochemistry of benzothiophene with other π-systems has been reported − ) (Figure B).…”

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Photocycloaddition of S,S-Dioxo-benzothiophene-2-methanol, Reactivity in the Solid State and in Solution: Mechanistic Studies and Diastereoselective Formation of Cyclobutyl Rings

et al. 2019

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The formation of cyclobutane rings is a promising strategy in the development of potential drugs and/or synthetic intermediates, typically challenging to obtain due to their constrained nature. In this work, the [2 + 2] photocycloaddition reaction of S,S-dioxobenzothiophene-2-methanol was explored in microcrystalline powders and its outcome was compared to that observed in solution. It was found that the molecular constraints inherited within the crystal lattice provide an optimal environment that leads to photodimer 4 as the major product in ca. 9.6:0.4 diastereomeric ratios with conversions >95%. The photoreaction was analyzed via X-ray, displaying a crystalline-to-amorphous transformation and showing that units of monomer 2 align to generate the corresponding dimer with a syn-head-to-tail regio-and diastereoselectivity. This result contrasted with that obtained in solution, where the diastereomeric ratio varied as a function of the excited state that is generated, to yield mixtures of dimers 4 and 5 (anti-head-to-tail), or exclusively 5 in the tripletsensitized photoreaction, in the presence of benzophenone. Density functional theory was used to elucidate a plausible detailed mechanism for the phototransformation, which aided in justifying the results that led to the corresponding dimers. X-ray crystallography allowed us to establish the stereochemical assignment of the obtained cyclobutyl rings. Thus, the use of solidstate or solution photochemistry can be used to gain control of diastereo-and regioselectivities in the formation of this important moiety.

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ChemInform Abstract: ON THE PHOTOCYCLOADDITION OF DIMETHYL ACETYLENEDICARBOXYLATE TO BENZO(B)THIOPHENE

Ditto¹,

Davis²,

Neckers³

1981

Chemischer Informationsdienst

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On the photocycloaddition of dimethyl acetylenedicarboxylate to benzo(b)thiophene

Cited by 16 publications

References 5 publications

Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene^,¹

Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene^,¹

Photocycloaddition of S,S-Dioxo-benzothiophene-2-methanol, Reactivity in the Solid State and in Solution: Mechanistic Studies and Diastereoselective Formation of Cyclobutyl Rings

ChemInform Abstract: ON THE PHOTOCYCLOADDITION OF DIMETHYL ACETYLENEDICARBOXYLATE TO BENZO(B)THIOPHENE

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On the photocycloaddition of dimethyl acetylenedicarboxylate to benzo(b)thiophene

Cited by 16 publications

References 5 publications

Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene,1

Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene,1

Photocycloaddition of S,S-Dioxo-benzothiophene-2-methanol, Reactivity in the Solid State and in Solution: Mechanistic Studies and Diastereoselective Formation of Cyclobutyl Rings

ChemInform Abstract: ON THE PHOTOCYCLOADDITION OF DIMETHYL ACETYLENEDICARBOXYLATE TO BENZO(B)THIOPHENE

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Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene^,¹

Photoaddition Reactions of Acetylene and Butadiyne Derivatives to Benzodithiophene^,¹