Studies on the Chemistry of Heterocyclics. XIX. The Application of the Hofmann and Curtius Rearrangements to the Preparation of 2-Thienylacetaldehydes

Mason, C. D.; Nord, F. F.

doi:10.1021/jo50006a008

Cited by 15 publications

(3 citation statements)

References 5 publications

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“…Perhaps the acyl isocyanate intermediate formed via Curtius rearrangement undergoes hydrolysis during a workup process to produce the cinnamamide. Formation of the primary amide as the exclusive product led us to consider whether this method could provide a general access to this valuable scaffold as a complement to the existing procedures. , After optimization with different conditions, use of 2.0 equiv of DPPA and 30 mol % of Cu(OTf) 2 in DMF/H 2 O (9.5:0.5) proved to be optimal (entry 4, Table ). Next, the scope of α-keto thioesters 1 was explored, as shown in Table .…”

Section: Resultsmentioning

confidence: 99%

“…Next, the scope of α-keto thioesters 1 was explored, as shown in Table . Various γ-substituted β,γ-unsaturated α-keto methylthioesters or α-substituted α-keto thioesters were successfully converted to their corresponding primary amides in moderate to good yields ( 4a – s ) . It is noteworthy that the α-keto thioesters having an alkyl group at the α-position were also found to be compatible under the reaction conditions ( 4t , u )…”

Section: Resultsmentioning

confidence: 99%

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Copper(II)-Catalyzed Reactions of α-Keto Thioesters with Azides via C–C and C–S Bond Cleavages: Synthesis of N-Acylureas and Amides

2018

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Cu(II)-catalyzed reaction of α-keto thioesters with trimethylsilyl azide (TMSN) proceeds with the transformation of the thioester group into urea through C-C and C-S bond cleavages, constituting a practical and straightforward synthesis of N-acylureas. When diphenyl phosphoryl azide (DPPA) is used instead as the azide source in an aqueous environment, primary amides are formed via substitution of the thioester group. The reactions are proposed to proceed through Curtius rearrangement of the initially formed α-keto acyl azide to generate an acyl isocyanate intermediate, which reacts further with an additional amount of azide or water and rearranges to afford the corresponding products. To demonstrate the potentiality of the method, one-step syntheses of pivaloylurea and isovaleroylurea, displaying anticonvulsant activities, have been carried out.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Copper(II)-Catalyzed Reactions of α-Keto Thioesters with Azides via C–C and C–S Bond Cleavages: Synthesis of N-Acylureas and Amides

2018

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“…Material (benzene), mp 152 -153°(lit. [8] 152 -1530), was irradiated for 11 days during which time the powder-photograph lines of the monomer had almost disappeared. The material was extracted (soxhlet) with benzene and the insoluble residue which contained small amounts of an oligomer was chromatographed.…”

Section: Introductionmentioning

confidence: 99%

Topochemistry Part XXXV. The Formation of Mixed Dimers from Solid Solutions of Trans‐Cinnamic Acids and Trans‐Cinnamides

Hung¹,

Lahav²,

Luwisch³

et al. 1972

Israel Journal of Chemistry

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Irradiation (λ >300 nm) of eight two‐component solid solutions of β‐arylacrylamides, prepared by melting and crystallising equimolar quantities of the amides tr‐ArCH:CHCONE where Ar=C6H5, p‐MeOC6H4, p‐ClC6H4, p‐MeC6H4, and 2‐thienyl, which appeared in the α crystal form, gave three photoproducts for each system studied: two α‐truxillic homodimers, derived from the respective monomers, and an α‐truxillic heterodimer. No other isomers were found. Similarly, two‐component solid solutions were prepared by melting and crystallising ring‐substituted cinnamic acids (tr‐ArCH:CHCO2H, where Ar=C6H5 (α‐form), p—ClC6H4(β), p‐MeC6H4(α), p‐MeOC6H4(γ), o‐ClC6H4(β) and o‐CH3C6H4(γ)) and irradiated. A solid solution of two α‐type acids (each photodimerising in the solid to α‐truxillic acid) behaved like the amides, affording two α‐truxillic homodimers and an α‐truxillic heterodimer. A solid solution of an α‐type acid with a β‐type acid (photodimerising to β‐truxinic acids) gave six photoproducts: three α‐truxillic acid dimers and three β‐truxinic acid dimers (i.e., four homodimers and two heterodimers). Irradiation of a solution of a γ‐type acid (non‐photodimerising in the solid state) with an α‐type acid afforded α‐truxillic dimers (two homodimers and one heterodimer). The above results are consistent with mutual miscibility of the two components which gives rise to mixed crystal formation and subsequent photo‐behaviour within each crystal which is characteristic of the particular lattice type. However, irradiation of the mixed crystals from p‐methoxycinnamic acid (γ‐type) and p‐chlorocinnamic acid (β‐type), which afford two α‐truxillic dimers (methoxy‐homodimer and methoxy, chloro‐heterodimer) and two β‐truxinic dimers (chloro‐homodimer and methoxy, chloro‐heterodimer) indicates that new phases, unobserved for the pure compounds, can also be generated. The new dimers were all characterised by the NMR and mass spectra of their dimethyl ester derivatives and, when possible, by conversion to known compounds.

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Side‐Chain Reactivity of Thiophenes. Thenyl Derivatives

Musumarra

1986

Chemistry of Heterocyclic Compounds: A Series of Monographs

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Studies on the Chemistry of Heterocyclics. XIX. The Application of the Hofmann and Curtius Rearrangements to the Preparation of 2-Thienylacetaldehydes

Cited by 15 publications

References 5 publications

Copper(II)-Catalyzed Reactions of α-Keto Thioesters with Azides via C–C and C–S Bond Cleavages: Synthesis of N-Acylureas and Amides

Copper(II)-Catalyzed Reactions of α-Keto Thioesters with Azides via C–C and C–S Bond Cleavages: Synthesis of N-Acylureas and Amides

Topochemistry Part XXXV. The Formation of Mixed Dimers from Solid Solutions of Trans‐Cinnamic Acids and Trans‐Cinnamides

Side‐Chain Reactivity of Thiophenes. Thenyl Derivatives

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