Über Synthesen und einige Eigenschaften von mono‐ und disubstituierten Bicyclo[4.2.2]decatetraenen

Carnadi, H. D.; Hildenbrand, P.; Richter, J.; Schröder, Gerhard

doi:10.1002/jlac.197819781221

Cited by 13 publications

(1 citation statement)

References 18 publications

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“…17 If this reaction is conducted in the presence of iodine, 23 is isomerized to 24, which can be isolated in low yield. 18,19 The most extensive investigations of benzene higher order cycloadditions are the intramolecular cycloadditions of alkoxy-substituted benzenes with naphthalene and anthracene that yield products like 25. 20,21 The work by Gilbert (Scheme 2) utilized 254 nm lamps and wavelengths down to 220 nm (Vycor filter), whereas in this work light above 290 nm (Pyrex filter) was used.…”

Section: Introductionmentioning

confidence: 99%

Photo-[4+4]-cycloaddition (para) of meta-substituted benzenes with 2-pyridones

Khatri

Vrubliauskas

Sieburth

2015

Tetrahedron Letters

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a b s t r a c tBenzene is unreactive as a photochemistry partner with 2-pyridone, however benzene substitution can allow for an efficient [4+4] (a k a, 'para') photocycloaddition. Productive substituents include alkoxy, cyano, ester, and trifluoromethyl, suggesting that inductively electron-withdrawing groups are sufficient, however a single fluorine substituent does not result in cycloaddition. When the product of this cycloaddition contains a conjugated system (e.g., an unsaturated ester) a secondary photocycloaddition can follow, forming triply bridged all-syn-[3]ladderane products.

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Section: Introductionmentioning

confidence: 99%

Photo-[4+4]-cycloaddition (para) of meta-substituted benzenes with 2-pyridones

Khatri

Vrubliauskas

Sieburth

2015

Tetrahedron Letters

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The IntramolecularDiels–Alder Reaction

Ciganek

1984

Organic Reactions

108

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The Diels–Alder reaction is one of the most useful reactions available to the synthetic organic chemist. It is thus surprising that the intramolecular version, in which both diene and dienophile are part of the same molecule, remained virtually unexplored for many years. Early examples were often the result of unexpected observations, and the many advantages of this reaction were recognized and put to use in the synthesis of complex polycyclic molecules only recently. In the intramolecular Diels–Alder reaction, two rings are formed in one step. In addition to the six‐membered ring formed by the [4 + 2]cycloaddition, the product contains a second ring, the size of which depends on the length of the chain connecting diene and dienophile. Of the two possible regiochemical modes of addition, that leading to the fused product usually predominates to the virtual exclusion of the bridged product. The Diels–Alder reaction proceeds through a highly ordered transition state that is reflected in large negative activation entropies. In the intramolecular version, some of the ordering has been accomplished in advance by making the two reacting functionalities part of the same molecule. This results in less negative activation entropies and increased reaction rates under often surprisingly mild conditions. On the other hand, by using forcing conditions one can sometimes carry out intramolecular Diels–Alder additions that would be doomed to failure in the intermolecular version. Lower reaction temperatures, together with the constraints imposed by the connecting chain, often result in pronounced regio‐ and stereoselectivity. Side reactions such as dimerization or polymerization can be avoided by using high dilution or low pressures in the gas phase. Examples where the bimolecular Diels–Alder reaction interferes with the intramolecular cyclization are rare. All of these features suggest that the intramolecular Diels–Alder reaction should be considered for any synthesis of a molecule containing a six‐membered ring fused to a second ring, especially if that ring is five‐ or six‐membered. Such a synthetic scheme may be made convergent by building up the diene and dienophile portions separately and connecting them just prior to the actual cyclization. Another potential use of the intramolecular Diels–Alder reaction that has not received much attention to date is as a supplement to the intermolecular Diels–Alder reaction in cases where the latter is unsuccessful or gives the wrong regio‐ or stereochemistry. By judicious choice of the connecting chain, the reaction may be made to proceed with the desired selectivity; this is followed by cleavage of the chain and conversion of the two ends to the desired functionalities. Once the feasibility of employing the intramolecular Diels–Alder reaction has been recognized, the main challenge often becomes the preparation of the substrate. A discussion of that aspect is beyond the scope of this chapter; however, by scanning the tables for the particular diene, dienophile, and chain one is interested in, and then referring to the original literature, it will often be possible to obtain some indications on how to proceed. An attempt has been made to cover the literature of the thermal intramolecular Diels–Alder reaction as completely as possible up to and including the year 1981. Many of the papers that appeared in 1982 and some from 1983 have also been included. More recent references are given in an addendum at the end of the tabular survey.

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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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Über Synthesen und einige Eigenschaften von mono‐ und disubstituierten Bicyclo[4.2.2]decatetraenen

Cited by 13 publications

References 18 publications

Photo-[4+4]-cycloaddition (para) of meta-substituted benzenes with 2-pyridones

Photo-[4+4]-cycloaddition (para) of meta-substituted benzenes with 2-pyridones

The IntramolecularDiels–Alder Reaction

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

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