A Mild and Efficient Method for Semmler-Wolff Aromatization; A Versatile Route tom-Alkoxy-,m-Halogeno-, andm-Thiocyanato-acetanilides

Tamura, Yasumitsu; Yoshimoto, Yoshihiko; Saito, Kiyoshi; Hoshino, Junichi; Kita, Yasuyuki

doi:10.1055/s-1980-29253

Cited by 18 publications

(4 citation statements)

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“…Whilst acetic anhydride alone, or in the presence of acetic acid, has been used, reported reaction times are lengthy. Alternatively, acetyl chloride with acetic anhydride in the presence of pyridine, ketene, or 1-ethoxyvinyl acetate promoted the Semmler–Wolff aromatisation under milder conditions. The proposed mechanism of Semmler–Wolff reaction encompasses several individual steps, commencing with O-acetylation of the oxime.…”

Section: Resultsmentioning

confidence: 99%

Development of Scalable Manufacturing Routes to AZD1981. Application of the Semmler–Wolff Aromatisation for Synthesis of the Indole-4-amide Core

Sulur

Sharma

Ramakrishnan

et al. 2012

Org. Process Res. Dev.

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A safe and efficient synthesis of AZD1981 is described in which the indole 4-amide core is formed by a Semmler− Wolff aromatisation of a cyclohexenone oxime fused to a pyrrole ring. The substrate was obtained via Paal−Knorr pyrrole synthesis, followed by incorporation of the key 3-arylthio substituent by reaction with 4-chlorophenylsulfenyl chloride. In this manner, the 1,2,3,4-substitution pattern of the AZD1981 core was regiospecifically established in a concise and efficient telescoped sequence. Accordingly, AZD1981 was obtained in 40% overall yield in six chemical steps, with two isolated crystalline intermediates.

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Section: Resultsmentioning

confidence: 99%

Development of Scalable Manufacturing Routes to AZD1981. Application of the Semmler–Wolff Aromatisation for Synthesis of the Indole-4-amide Core

Sulur

Sharma

Ramakrishnan

et al. 2012

Org. Process Res. Dev.

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“…By using these ketene acetal-type reagents, we subsequently reported the synthesis of acetanilides by Semmler–Wolff aromatization , and the preparation of carboxylic anhydrides. , However, for the preparation of ketene acetal-type reagents, highly toxic mercury enolate was required (Scheme , eq 1). Wasserman et al succeeded in the effective preparation of 1-alkoxyvinyl esters from alkoxyacetylene.…”

Section: Introductionmentioning

confidence: 99%

“…1 replacement of the methyl group on the isopropenyl group into the alkoxy group strongly improved the reactivity and enabled the carbonylation of a wide range of nucleophiles (Scheme 2, eq 3). 2−4 By using these ketene acetal-type reagents, we subsequently reported the synthesis of acetanilides by Semmler−Wolff aromatization 5,6 and the preparation of carboxylic anhydrides. 7,8 However, for the preparation of ketene acetal-type reagents, highly toxic mercury enolate was required (Scheme 3, eq 1).…”

Section: Introductionmentioning

confidence: 99%

1-Alkoxyvinyl Ester as an Excellent Acyl Donor: Efficient Macrolactone Synthesis

et al. 2021

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Ketene acetal derivatives, such as 1-alkoxyvinyl esters and O-silyl ketene acetals, belong to the category of O-substituted enols of esters, which easily react with various types of nucleophiles, Nu–H, under neutral conditions to give the corresponding acylated and silylated products in excellent yields only by evaporation of the generated volatile esters. Silyl ketene acetals can be easily synthesized by various simple procedures, whereas 1-alkoxyvinyl esters require an equimolar or catalytic amount of a mercury salt to synthesize them. This drawback prevented the advancement of the chemistry of 1-alkoxyvinyl esters. In 1993, we developed a useful synthetic method of 1-alkoxyvinyl esters using a small amount (0.5–1 mol %) of a ruthenium catalyst. Encouraged by this discovery, we subsequently developed various reactions and applied them to the synthesis of natural products. It is noteworthy that the stereoselective total synthesis of fredericamycin A was achieved by the combined use of these reactions. Macrocyclization was variously utilized for the synthesis of natural macrolides by two types of approaches: direct macrolactonization of α,ω-hydroxy acids or intermolecular esterification between an acid and alcohol followed by a ring-closure step. Additionally, several new reactions using 1-alkoxyvinyl esters or their analogs as key intermediates on the basis of our methods were recently reported. In this paper, we introduce our efforts from the synthesis of 1-alkoxyvinyl esters to the application such as natural product syntheses and recent advancements.

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“…Moreover, Kita revealed that ynol ethers could serve as coupling reagents for ester and lactone synthesis from hydroxyl compounds and carboxylic acids . In addition, Kita also reported a Semmer–Wolff aromatization between cyclohexanone oxime and α-acyloxy enol esters …”

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confidence: 99%

One-Pot Reaction of Carboxylic Acids, Ynol Ethers, and m-CPBA for Synthesis of α-Carbonyloxy Esters

2019

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A novel one-pot reaction of carboxylic acids, ynol ethers, and m-CPBA for the synthesis of α-carbonyloxy esters in the presence of Ag 2 O is described. This process provides a direct approach to α-carbonyloxy esters with the achievement of formation of three C−O bonds. The protocol is featured with readily available starting materials and broad substrate scope. Control reactions and isotope-labeling reactions were conducted to elucidate a plausible mechanism.

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A Mild and Efficient Method for Semmler-Wolff Aromatization; A Versatile Route tom-Alkoxy-,m-Halogeno-, andm-Thiocyanato-acetanilides

Cited by 18 publications

References 0 publications

Development of Scalable Manufacturing Routes to AZD1981. Application of the Semmler–Wolff Aromatisation for Synthesis of the Indole-4-amide Core

Development of Scalable Manufacturing Routes to AZD1981. Application of the Semmler–Wolff Aromatisation for Synthesis of the Indole-4-amide Core

1-Alkoxyvinyl Ester as an Excellent Acyl Donor: Efficient Macrolactone Synthesis

One-Pot Reaction of Carboxylic Acids, Ynol Ethers, and m-CPBA for Synthesis of α-Carbonyloxy Esters

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