Oxidative Cleavage of 3‐Alkoxy‐2,5‐dihydrofurans and its Application to the De Novo Synthesis of Rare Monosaccharides as Exemplified by <scp>L</scp>‐Cymarose

Brasholz, Malte; Reißig, Hans‐Ulrich

doi:10.1002/anie.200604078

Cited by 25 publications

(13 citation statements)

References 43 publications

(9 reference statements)

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“…of pyridine, in dichloromethane), both under light exclusion ,. [6a] These methods are considerably milder and furnished 14 in 93 and 94 % yield, respectively (Table , Entries 2 and 3). Furthermore, we studied the cyclization of allenylamine 3 promoted by Pd(PPh 3 ) 4 (5 mol‐%), which gave 14 in only 56 % yield…”

Section: Resultsmentioning

confidence: 99%

“…We discovered that the additions of lithiated alkoxyallenes to nitrones lead directly to 1,2‐oxazine ring formation and that three‐component reactions with nitriles and carboxylic acids provide highly substituted pyridine derivatives (Scheme ) . These useful and highly flexible cyclization reactions were employed to prepare a variety of heterocycles that are either of interest as intermediates for the synthesis of natural products and their analogs or heteroaromatic compounds with extended π‐systems . In a preliminary report, we described additions of lithiated methoxyallene to imines to form the expected allenylamines, which were subsequently cyclized to 2,5‐dihydropyrrole derivatives .…”

Section: Introductionmentioning

confidence: 99%

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Efficient Syntheses of 2,5‐Dihydropyrroles, Pyrrolidin‐3‐ones, and Electron‐Rich Pyrroles from N‐Tosylimines and Lithiated Alkoxyallenes

et al. 2017

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N‐Tosylimines and lithiated alkoxyallenes afforded the corresponding allenyl N‐tosylamines in good to excellent yields. The 5‐endo‐trig cyclizations of these intermediates to 2,5‐dihydropyrrole derivatives were achieved under strongly basic conditions with potassium tert‐butoxide or under milder conditions with either silver(I) or gold(I) catalysis. In general, gold chloride catalyzed reactions occurred with the lowest catalyst loadings and delivered the best yields. With phenyl‐substituted 2,5‐dihydropyrrole, we investigated typical reactions such as oxidative and reductive transformations. The acid‐promoted hydrolysis of the enol ether moieties of three 2,5‐dihydropyrroles furnished the corresponding pyrrolidin‐3‐ones, which were reduced to give 3‐hydroxypyrrolidine derivatives in good yields. The aromatization of 2,5‐dihydropyrroles to 3‐methoxypyrrole derivatives was accomplished by base treatment, which caused the elimination of p‐tolyl sulfinate. Electron‐rich pyrrole derivatives were synthesized in good yields even on a large scale. All of the experiments illustrate the efficacy and flexibility of the alkoxyallene approach to pyrrole derivatives.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Efficient Syntheses of 2,5‐Dihydropyrroles, Pyrrolidin‐3‐ones, and Electron‐Rich Pyrroles from N‐Tosylimines and Lithiated Alkoxyallenes

et al. 2017

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“…For example, cyclohexanone‐derived allenyl alcohol 10 furnished solely 2,5‐dihydrofuran 11 (90 %), and adamantane derivative 12 was reported to give oxirane 13 in 92 % yield (see Scheme ). On the other hand, more recent Au I /pyridine‐catalyzed transformations of allenyl alcohols have been presented as an often superior method in terms of the exclusive formation of 2,5‐dihydrofurans 14d–f. Prompted by these reports, a series of experiments were carried out using freshly prepared primary product 12 .…”

Section: Resultsmentioning

confidence: 99%

Reactions of Cycloaliphatic Thioketones and Their Oxo Analogues with Lithiated Methoxyallene: A New Approach to Vinylthiiranes

Jasiński

Mlostoń

Stolarski

et al. 2014

Chemistry An Asian Journal

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Admantanethione smoothly reacted with lithiated methoxyallene at low temperatures yielding the expected allenyl-substituted thiolate, which upon aqueous work-up underwent spontaneous 1,3-cyclization to afford a hitherto unknown methoxy-substituted vinylthiirane derivative. The analogous reaction with adamantanone led to the corresponding allenyl alcohol that can be isolated and--depending on the conditions applied--either be converted into the corresponding vinyloxirane or into the 2,5-dihydrofuran derivative. Sterically more crowded thioketones were also combined with lithiated methoxyallene, but in these cases competitive 1,5-cyclization leading to isomeric dihydrothiophene derivatives was observed. DFT calculations of model intermediates and products show distinct energy differences of the sulfur and the corresponding oxygen compounds. Desulfurization of the adamantanethione-derived vinylthiirane yielded a methoxy-substituted 1,3-diene that was studied in cycloadditions with electron-deficient dienophiles. Whereas in the case of tetracyanoethylene the corresponding cyclobutane derivative was formed, the reaction with nitrosobenzene provided the expected 1,2-oxazine derivative. By reductive cleavage of the N-O bond this heterocycle was converted into an unsaturated amino alcohol bearing an adamantane moiety.

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“…Reissig and Brasholz reported a de novo synthesis of l ‐cymarose via dihydropyran intermediate B (Scheme ) . The key step is also DDQ‐mediated oxidative rearrangement.…”

Section: De Novo Synthesis Of Monosaccharides Via Dihydropyran Intermmentioning

confidence: 99%

De Novo Synthesis of Mono‐ and Oligosaccharides via Dihydropyran Intermediates

Song

Wang

Tang

2017

Chemistry An Asian Journal

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The importance of carbohydrates is evident by their essential role in all living systems. Their syntheses have attracted attention from chemists for over a century. Most chemical syntheses in this area focus on the preparation of carbohydrates from naturally occurring monosaccharides. De novo chemical synthesis of carbohydrates from feedstock starting materials has emerged as a complementary method for the preparation of diverse mono- and oligosaccharides. In this review, the history of de novo carbohydrate synthesis is briefly discussed and particular attention is given to methods that address the formation of glycosidic bonds for potential de novo synthesis of oligosaccharides. Almost all methods of this kind involve the formation of dihydropyran intermediates. Recent progress in forming dihydropyrans by Achmatowicz rearrangement, hetero-Diels-Alder cycloaddition, ring-closing metathesis, and other methods is also elaborated.

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Oxidative Cleavage of 3‐Alkoxy‐2,5‐dihydrofurans and its Application to the De Novo Synthesis of Rare Monosaccharides as Exemplified by L‐Cymarose

Cited by 25 publications

References 43 publications

Efficient Syntheses of 2,5‐Dihydropyrroles, Pyrrolidin‐3‐ones, and Electron‐Rich Pyrroles from N‐Tosylimines and Lithiated Alkoxyallenes

Efficient Syntheses of 2,5‐Dihydropyrroles, Pyrrolidin‐3‐ones, and Electron‐Rich Pyrroles from N‐Tosylimines and Lithiated Alkoxyallenes

Reactions of Cycloaliphatic Thioketones and Their Oxo Analogues with Lithiated Methoxyallene: A New Approach to Vinylthiiranes

De Novo Synthesis of Mono‐ and Oligosaccharides via Dihydropyran Intermediates

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