Influence of Heteroaromatic Amines to Knoevenagel Condensation

Yamanaka, Hiroshi; Yokoyama, Masaaki; Sakamoto, Takao; Shiraishi, Taizo; Sagi, Mataichi; Mizugaki, Michinao

doi:10.3987/r-1983-08-1541

Cited by 35 publications

(9 citation statements)

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“…According to the Hann and Lapworth mechanism, the Knoevenagel reaction can proceed via an aldol‐type β ‐hydroxy dicarbonyl compound. Moreover, the intermediate compound can be dehydrated and then decarboxylated to give the final product, an α , β ‐ and/or β , γ ‐unsaturated acid . Based on these findings, we assumed that 4M2H could be formed via the intermediate β ‐hydroxy dicarbonyl compound, which is the key compound for selectivity in the formation of either 4M2H or 4M3H (Figure ).…”

Section: Resultsmentioning

confidence: 93%

First identification of the odour‐active unsaturated aliphatic acid (E)‐4‐methyl‐3‐hexenoic acid in yuzu (Citrus junos Sieb. ex Tanaka)

Miyazato¹,

Hashimoto²,

Hayashi³

2012

Flavour & Fragrance J

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We have investigated the aroma of yuzu (Citrus junos Sieb. ex Tanaka). Application of the aroma extract dilution analysis technique allowed us to determine a sequence of the odour‐active compounds in yuzu volatile oil. In this study, we confirmed the presence of an unknown odorant that possesses a sweaty odour and a relatively high flavour dilution factor. In order to identify the unknown compound, the concentrated volatile acid fraction of yuzu volatile oil was obtained, using an enrichment procedure consisting of the combination of the sub‐extraction of an acidic component with a basic aqueous solution and subsequent affinity chromatography with an Oasis MAX cartridge. Gas chromatography–olfactometry and multi‐dimensional gas chromatography–mass spectrometry analyses revealed that the unknown compound was (E)‐4‐methyl‐3‐hexenoic acid [(E)‐4M3H]. (E)‐4M3H was identified for the first time as an odour‐active unsaturated aliphatic acid in yuzu. Additionally, both (Z)‐ and (E)‐4M3H were stereoselectively synthesised over two steps comprised of the iron‐catalysed carbometalations of homopropargylic alcohols with Grignard reagents, followed by oxidation. On the basis of sensory evaluation, the orthonasal odour detection threshold of the (E)‐isomer was 10‐fold to 100‐fold lower than that of the (Z)‐isomer. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 93%

First identification of the odour‐active unsaturated aliphatic acid (E)‐4‐methyl‐3‐hexenoic acid in yuzu (Citrus junos Sieb. ex Tanaka)

Miyazato¹,

Hashimoto²,

Hayashi³

2012

Flavour & Fragrance J

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“…Olefin 9d could stem from a deconjugative Knoevenagel condensation of aldehyde 11 and malonic acid [18] or monomethyl malonate. [19] Because aldehyde 11 could not be traced back readily to a commercially available naphthalene, we synthesized the aromatic subunit 14 de novo by a Dötz reaction [20] between the chromium carbene complex 12 [21] and the siloxylated butyne 13. [22,23] In their 10-step synthesis of racemic arizonin C1, Brimble et al likewise recognized that its naphthalene portion is best constructed de novo.…”

Section: Resultsmentioning

confidence: 99%

First Synthesis of the Pyrano‐Naphthoquinone Lactone (–)‐Arizonin C1

2011

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“…[118f ] The dialdehyde from 158 was treated with a half ester of malonic acid under modified Knoevenagel condensation [128] conditions to deliver the ,γ-unsaturated ester. This is unknown for dimeric compounds, though quite familiar in the case of monomers.…”

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Dimeric Pyranonaphthoquinones: Isolation, Bioactivity, and Synthetic Approaches

2016

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The dimeric pyranonaphthoquinones, “bis versions” of the naphtho[2,3‐c]pyran‐5,10‐dione moiety, comprises a group of antibiotics that have been isolated from a variety of sources including plants, bacteria, fungi, and insects. This review discusses the known naturally occurring dimeric pyranonaphthoquinones, their isolation and bioactivity, and synthetic approaches towards them that have helped to confirm their structures, as well as to resolve structural uncertainties such as stereochemistry. The major focus has been on the synthetic approaches adopted to complete the challenging total synthesis of the natural isolates and analogues.

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Influence of Heteroaromatic Amines to Knoevenagel Condensation

Cited by 35 publications

References 0 publications

First identification of the odour‐active unsaturated aliphatic acid (E)‐4‐methyl‐3‐hexenoic acid in yuzu (Citrus junos Sieb. ex Tanaka)

First identification of the odour‐active unsaturated aliphatic acid (E)‐4‐methyl‐3‐hexenoic acid in yuzu (Citrus junos Sieb. ex Tanaka)

First Synthesis of the Pyrano‐Naphthoquinone Lactone (–)‐Arizonin C1

Dimeric Pyranonaphthoquinones: Isolation, Bioactivity, and Synthetic Approaches

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