Heterocycles in organic synthesis: thiazoles and triazoles as exemplar cases of synthetic auxiliaries

Dondoni, Alessandro

doi:10.1039/c002586k

Cited by 82 publications

(28 citation statements)

References 126 publications

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“…[16] This was also an interesting challenge in the field of the catalytic asymmetric aldol reaction, as application of heterocyclic methyl ketone could possibly expand the still-narrow scope of the Shibasaki and Trost catalysts. [16] This was also an interesting challenge in the field of the catalytic asymmetric aldol reaction, as application of heterocyclic methyl ketone could possibly expand the still-narrow scope of the Shibasaki and Trost catalysts.…”

Section: Resultsmentioning

confidence: 99%

“…Subsequently, en route to the ulosonic acid derivatives, we decided to test also the use of 2-acetylthiazole (6), successfully introduced by Dondoni, to the chemistry of ulosonic acids. [16] This was also an interesting challenge in the field of the catalytic asymmetric aldol reaction, as application of heterocyclic methyl ketone could possibly expand the still-narrow scope of the Shibasaki and Trost catalysts. [2] Application of (R)-ProPh resulted in the formation of aldol 7 in 50 % yield with ca.…”

Section: Resultsmentioning

confidence: 99%

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Direct Aldol Reaction of Pyruvic Derivatives: Catalytic Attempt To Synthesize Ulosonic Acids

et al. 2012

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The catalytic asymmetric aldol reaction of pyruvic aldehyde dimethyl acetal and 2‐acetylthiazole with sugar aldehydes is demonstrated to be the key step in the synthesis of 3‐deoxy‐2‐ulosonic acids. Efficient and stereoselective pyruvate aldol reactions are catalyzed by metal‐based chiral Trost and Shibasaki catalysts. The presented synthetic methodology mimics aldolase‐catalyzed reactions by direct activation of C3 pyruvate equivalents with the use of metal‐based chiral catalysts en route to the synthesis of 2‐keto‐3‐deoxy‐D‐glucosonic acid and 3‐deoxy‐D‐manno‐2‐octulosonic acid derivatives.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Direct Aldol Reaction of Pyruvic Derivatives: Catalytic Attempt To Synthesize Ulosonic Acids

et al. 2012

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“…Thiazole (C 3 H 3 NS) is a five-membered heterocyclic aromatic compound found in many natural products [1][2][3][4] including vitamin B1, and has been widely incorporated into synthetic molecules including pharmaceuticals, [5] catalysts [6] and dyes [7].…”

Section: From Cysteine To Thiazoles and Peptidomimeticsmentioning

confidence: 99%

“…6). Thiazoles have found wide application within peptidomimetics, due in part to effective methods for installing substituents at each of the ring carbons [6,[56][57][58].…”

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Thiazoles in Peptides and Peptidomimetics

Mak

Fairlie

2015

Topics in Heterocyclic Chemistry

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“…[1][2][3][4] It is obvious, furthermore, that compounds with the thiazole ring have potential biological activity. 5,6 The most salient method to synthesize thiazoles is the Hantzsch thiazole synthesis where α-haloketones are reacted with thioamides.…”

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confidence: 99%

Convenient One-Pot Two-Step Synthesis of 1,3-Thiazoles via Organocatalyzed Epoxidation of Nitroolefins

Wei¹,

Weiß²,

Tsogoeva³

2012

Synthesis

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A convenient novel one-pot two-step strategy and its substrate scope for the synthesis of 1,3-thiazole heterocycles via organocatalytic epoxidation of nitroolefins with the TBHP/DBU system, and subsequent reaction of α-nitroepoxides with thioamides is reported.Thiazole heterocycles are of prominent importance because of their potential as versatile building blocks for pharmaceuticals and natural products. 1-4 It is obvious, furthermore, that compounds with the thiazole ring have potential biological activity. 5,6 The most salient method to synthesize thiazoles is the Hantzsch thiazole synthesis where α-haloketones are reacted with thioamides. 7 One of the less explored methods is to prepare thiazoles from the corresponding epoxides (e.g., 2-chlorooxiranes, α-nitroepoxides) and thioamides or thioureas. 8 For the synthesis of epoxides diverse approaches to catalytic epoxidations have been developed in recent years. 9 Newman first reported the thiazole synthesis from the corresponding α-nitroepoxides (generated from nitroolefins with H 2 O 2 /NaOH system). 8a,b In continuation of our research on organocatalytic epoxidation reactions, 10 we decided to develop an organocatalytic epoxidation of nitroolefins with an intention to further apply the corresponding products, α-nitroepoxides, without workup and purification for the synthesis of 1,3-thiazoles.Notably, one-pot processes, in which chemical transformations are carried out without intermediate isolation and purification steps, are very attractive and sustainable methods in modern synthetic chemistry due to the reduction of time, costs, materials, and waste generation. 11Very recently, we disclosed a facile approach to thiazole derivatives: 12 one-pot two-step synthesis, which involves an organocatalytic epoxidation of nitroolefins with TBPH/DBU (t-BuOOH/1,8-diazabicyclo[5.4.0]undec-7-ene) system, followed by reaction with different thiobenzamides at room temperature (Scheme 1). Herein we report the examined substrate scope (20 examples) in our one-pot two-step process using the optimized reaction conditions, as well as propose a plausible reaction mechanism for 1,3-thiazole formation starting from α-nitroepoxides. Concerning our idea to develop a one-pot procedure towards thiazole synthesis, we first studied the epoxidation of β-methyl-β-nitrostyrene (1). The known strategy for epoxidation of α,β-unsaturated δ-lactones and other enones using anhydrous TBHP as an oxidant and DBU as a base (at 120 mol% loading) at 0°C 13 was recently extended to the epoxidation of the more challenging nitroolefins as substrates. 12 In order to develop a catalytic epoxidation of β-methyl-β-nitrostyrene (1), we used merely catalytic amounts of DBU in combination with TBHP as oxidant. After an optimization series, it was found that DBU could be used in only 5 mol% loading in n-hexane at room temperature to generate high conversions of the corresponding α-nitroepoxide 2 after one hour reaction time. Epoxide 2 can be used directly without any Scheme 1 One-pot two-step process for the s...

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Heterocycles in organic synthesis: thiazoles and triazoles as exemplar cases of synthetic auxiliaries

Cited by 82 publications

References 126 publications

Direct Aldol Reaction of Pyruvic Derivatives: Catalytic Attempt To Synthesize Ulosonic Acids

Direct Aldol Reaction of Pyruvic Derivatives: Catalytic Attempt To Synthesize Ulosonic Acids

Thiazoles in Peptides and Peptidomimetics

Convenient One-Pot Two-Step Synthesis of 1,3-Thiazoles via Organocatalyzed Epoxidation of Nitroolefins

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