Thermolysis of Imidates: A New Method for the Generation of Carbonyl Ylides

Nikolaev, Vsevolod V.; Linden, Anthony; Heimgartner, Heinz

doi:10.1002/hlca.200790239

Cited by 3 publications

(1 citation statement)

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“…of benzo-fused 1,4-dioxa-6-azaspiro [4.4]nonanes 42 in Scheme 10 is effected by thermolysis at 120 °C of dimethyl 2-[(3-oxo-3H-isoindol-1-yl)oxy]malonate 41 as substrate. 22 The heat promotes a [1,4]-hydrogen shift in the imidic -N=C-O-CH-moiety resulting in a reactive carbonyl moiety which is trapped by the carbonyl function in benzaldehyde. The cycloadduct 42 is formed with both high regioselectivity and high stereoselectivity: the spiranes 42a and 42b are formed as a 71:1 mixture.…”

Section: Synthesismentioning

confidence: 99%

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Undheim

2016

Synthesis

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Spirocyclic scaffolds are embedded in several families of natural products. In the spirocyclic structure, the two rings constituting the spirane are linked through a common carbon atom. This review covers families of compounds that have three heteroatoms directly attached to the spirocarbon. Common heteroatoms are nitrogen, oxygen and sulfur, constituting spirocyclic orthoesters, ortholactones, orthothioesters and orthoaminals, or combinations thereof. Embedded spirocyclic scaffolds introduce steric restrictions and thereby influence bioactivity. In polymer chemistry, synthetic ortholactones may serve as monomers. Synthesis of anomeric spironucleosides will afford molecules where the basic unit is in a fixed conformation around the N-glycosidic bond. Synthesis of glycosidic and 2-deoxyglycosidic ortholactones in disaccharides and regioselective reductive cleavage of cyclic orthoesters result in stereoselective β-(1→4)-glycosidic bond formation. Pyranose and furanose free-radical chemistry via spirocyclic orthoesters can be applied in the generation of carbacyclic sugars and nucleosides. 1 Introduction 2 Heteraspiro[3.m]alkanes 3 Heteraspiro[4.m]alkanes 4 Heteraspiro[5.m]alkanes 5 Conclusion Key words tri(α-hetera)spiranes, spiroannulations, stereoselective syntheses, spirocyclic nucleosides, spirocyclic glycosides, polymer monomers 2 Heteraspiro[3.m]alkanes 2.1 Heteraspiro[3.4]octanes 2.1.1 5,8-Dioxa-1-azaspiro[3.4]octane Cyclic ketene acetals react with phenyl isocyanate to afford the corresponding spiro compounds. Scheme 1 shows a synthesis of a spirane, 6-methyl-1-phenyl-5,8-dioxa-2-oxo-1-azaspiro[3.4]octane (2). 12 In general, the β-carbon atom in the double bond of ketene acetals has an anionic character and forms an equimolar adduct with isocyanates. The adduct formation is often exothermic and may be carried out neat or in a solvent. In the preparation of 2, control of SYNTHESIS0 0

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Section: Synthesismentioning

confidence: 99%

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Undheim

2016

Synthesis

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Carbanions and Electrophilic Aliphatic Substitution

Birsa

2007

Organic Reaction Mechanisms Series

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A Simple One‐Pot Synthesis of N‐Alkyl‐2,5‐diaryl‐1,3‐dioxol‐4‐amines

Bayat

Nasri

2011

Helvetica Chimica Acta

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An efficient procedure for the synthesis of N-alkyl-2,5-diaryl-1,3-dioxol-4-amines 3 via a one-pot reaction of aromatic aldehydes 2 and alkyl isocyanides 1 at room temperature in good yields is described (Scheme 1, Table).Introduction. A number of synthetic routes for 1,3-benzodioxoles have been reported [7 -10], and many syntheses of 1,3-dioxoles via the reaction of a-diazo ketones with carbonyl derivatives have been described [11]. As part of our ongoing studies on the development of simple synthetic methods in heterocyclic chemistry, for e.g., the synthesis of iminospiro-g-lactones, 2H-pyrano[2,3-d]pyrimidine derivatives, and 2,5-diaminofuran derivatives [12], and our interest in isocyanide-based reactions, we report herein an efficient synthesis of N-alkyl-2,5-diaryl-1,3-dioxol-4-amines, starting from simple and readily available precursors. To the best of our knowledge, there are no reports on the synthesis of these compounds via isocyanide-based reactions.

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Thermolysis of Imidates: A New Method for the Generation of Carbonyl Ylides

Cited by 3 publications

References 84 publications

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Spirocyclic Orthoesters, Orthothioesters and Orthoaminals in the Synthesis and Structural Modification of Natural Products

Carbanions and Electrophilic Aliphatic Substitution

A Simple One‐Pot Synthesis of N‐Alkyl‐2,5‐diaryl‐1,3‐dioxol‐4‐amines

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