Cycloadditionen von 3,4‐Dimethoxyfuran an Dienophile

Iten, Peter X.; Hofmann, A.; Eugster, C. H.

doi:10.1002/hlca.19790620717

Cited by 19 publications

(9 citation statements)

References 13 publications

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“…Initial studies were performed with the ester (12) in THF at -78°C (Scheme 4). The silyl enol ether (19) was formed in high yield. However, when the temperature was lowered to -90°C, reaction with the same electrophiles led to a mixture of the alcohol (18) and the desired adduct.…”

Section: Methodsmentioning

confidence: 99%

Development of Methodology Based on the Use of the 7-Oxabicyclo[2.2.1]heptanyl System for the Preparation of carbohydrate Derivatives

Ager¹,

East²

1994

HETEROCYCLES

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The 7-oxabicyclo:2,?,!jheptany! system provides 2 rapid entry to carbohydrate derivatives in a stereoselective manner by virtue of the rigid framework. The formation of this bicyclic system through a Diels-Alder reaction of furan with a number of dienophiles is influenced by the substitution on the dienophile. Use of an anion stabilising group as a carbonyl equivalent has previously led to a ring opening reaction of the bicyclic system. However, anion chemistry can be used to functionalise the bicyclic system, and used for the introduction of a hydroxy group that allows, in turn, a method for the preparation of hexose derivatives.As part of our work to investigate the reactions of the 7-oxabicyclo[2.2.l]heptanyl system for the preparation of tetrahydrofuran derivative^,^ it came to our attention that, as others have ~e e n ,~.~ this bicyclic system has great potential for the synthesis of carbohydrate derivatives, other natural products, and their a n a~o~u e s~~' -~ but not all of the latent functionality was being put to good use.We, therefore, set out to investigate the use of the 7-oxabicyclo[2.2.l]heptanyl system for the preparation of carbohydrate analogues, and to augment the chemistry of these systems to allow the preparation of hexose derivatives. The pivotal compound to our strategy became the ketone (I), as used by Vogel, because of the flexibility available for the introduction of functionality at carbon atoms C-5. and -6.3353'0 * Dedicated to Professor Alan Katritzky on the occasion of his 65th birthday.

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Section: Methodsmentioning

confidence: 99%

Development of Methodology Based on the Use of the 7-Oxabicyclo[2.2.1]heptanyl System for the Preparation of carbohydrate Derivatives

Ager¹,

East²

1994

HETEROCYCLES

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“…It has recently been found that under thermal conditions 1 easily reacts with maleic anhydride and its monomethyl derivative, but not with dimethylmaleic anhydride (2) [3]. This is probably due to steric hindrance resulting from the location of two methyl groups on the double bond of the dienophile.…”

mentioning

confidence: 98%

“…Ilhept-5-ene-2,3-dicarboxylic anhydride, and its hydrogenation product 8 is Sendo, 6endo- CDC13, 100 MHz [3]. …”

mentioning

confidence: 99%

“…As an active diene (more active than furan itself), 3,4-dimethoxyfuran (1) affords with many dienophiles the respective cycloadducts in a high yield [2]. It has recently been found that under thermal conditions 1 easily reacts with maleic anhydride and its monomethyl derivative, but not with dimethylmaleic anhydride (2) [3]. This is probably due to steric hindrance resulting from the location of two methyl groups on the double bond of the dienophile.…”

mentioning

confidence: 99%

“…Comparison of the NMR. spectra of 3 and 8 with those of the model compounds 5-7 [3], and of 9 [3] and 10 [6], respectively (s. Table), clearly shows that the former has the proposed structure 3 and that hydrogenation has occurred from the exoface to yield exclusively 8.…”

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confidence: 99%

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High‐pressure [2 + 4]‐cycloaddition of dimethylmaleic anhydride to 3,4‐dimethoxyfuran; synthesis of dimethoxycantharidin preliminary communication

Jurczak¹,

Kozluk²,

Filipek³

et al. 1982

Helvetica Chimica Acta

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As an active diene (more active than furan itself), 3,4-dimethoxyfuran (1) affords with many dienophiles the respective cycloadducts in a high yield [2]. It has recently been found that under thermal conditions 1 easily reacts with maleic anhydride and its monomethyl derivative, but not with dimethylmaleic anhydride (2) [3]. This is probably due to steric hindrance resulting from the location of two methyl groups on the double bond of the dienophile. Since all Diets-Alder reactions -in particular those with steric hindrance -are pressure-sensitive [4], we resolved to perform the title reaction under conditions of static high pressure. Scheme

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The Retro–Diels–Alder Reaction PartI.CCDienophiles

Rickborn

1998

Organic Reactions

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The Diels–Alder (“DA”) reaction is so familiar to organic chemists that the retro‐Diels–Alder or retro‐diene reaction (hereafter “rDA”) requires no conceptual introduction. However, a working definition is needed to indicate the coverage of this review. The intent is to include all reported examples of the general skeletal process excluded in this chapter. Any of the atoms in the starting material (cycloadduct) may be carbon or heteroatom, and substituents on all positions are allowed. In addition, any bond order available to the element in any oxidation state is included, as well as bonding to non‐nearest neighbor atoms (bicyclics, etc.). The volume of literature required separation of this review into two parts. Part I covers all expelled C–C dienophiles, i.e. those reactions that generate a new carbon‐carbon double or triple bond in the dienophile that is formed. Part II, to appear later, covers those expelled dienophiles in which one or both atoms is a heteroatom. Certain specific topics are intentionally omitted. These are: rDA reactions invoked under mass spectral conditions; rDA reactions of polymeric substrates; Electrocyclic processes, some of which are arguably very similar to rDA reactions (these are not addressed unless needed for clarification of an rDA sequence); and a thorough discussion of homo‐rDA reactions. CAS‐Online searches resulted in ca. 1,300 references, of which ca. 900 proved pertinent to the rDA topic as defined and delimited above. Active literature searching was halted in April 1995, but occasional more recent articles are included. Over 2,500 pertinent references were eventually found. Most were obtained by perusal of primary literature (articles) and secondary sources (books and reviews). Computer based search success was limited mainly by the failure of authors or abstractors to key‐word this topic, an especially common occurrence when the expelled dienophile was a simple substance such as N 2 or CO 2 . Overall, approximately 3,500 books, chapters, reviews, articles, and abstracts were consulted in an effort to make this review as comprehensive as possible. This was done with the certainty that some pertinent literature would be missed, tempered by the view that these omissions are probably also lost to any future rational search method. Many secondary sources proved valuable not only for in‐depth discussion of certain rDA reaction types, but also for providing comparisons with related topics. To assist the reader, these secondary sources are referenced (alphabetically by first author within broad subject areas) with a title or brief note on the topic(s) addressed. The first group lists earlier reviews with primary focus on rDA reactions, followed by items of Historical/General Interest, reviews that deal with Experimental Methods, DA reactions (general and specific), reviews of Related Topics (these impinge in more or less significant ways on rDA reactions), and general treatments of Theory and Mechanism.

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Cycloadditionen von 3,4‐Dimethoxyfuran an Dienophile

Cited by 19 publications

References 13 publications

Development of Methodology Based on the Use of the 7-Oxabicyclo[2.2.1]heptanyl System for the Preparation of carbohydrate Derivatives

Development of Methodology Based on the Use of the 7-Oxabicyclo[2.2.1]heptanyl System for the Preparation of carbohydrate Derivatives

High‐pressure [2 + 4]‐cycloaddition of dimethylmaleic anhydride to 3,4‐dimethoxyfuran; synthesis of dimethoxycantharidin preliminary communication

The Retro–Diels–Alder Reaction PartI.CCDienophiles

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