A New Synthesis of the Bullvalene System

Vogel, Emanuel; Grimme, Wolfram; Meckel, W.; Riebel, H. J.; Oth, Jean F. M.

doi:10.1002/anie.196605901

Cited by 8 publications

(2 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A different procedure for the synthesis of dimethyl bullvalenedicarboxylate (41) consisted of the irradiation of dimethyl cis-4a,8a-dihydronaphthalene-4a,8a-dicarboxylate (5′) in methanol by a low-pressure mercury lamp (Scheme 18). 30 This transformation was mechanistically related to that found in the synthesis of 1 by Jones and Scott (see Scheme 5). 13 Scheme 18 Alternative preparation of dimethyl bullvalenedicarboxylate Diphenylbullvalene (45) was alternatively prepared by reaction of tricarbonylcyclooctatetraeneiron (2′) with diphenylacetylene at high temperatures (ca.…”

Section: Scheme 17 Synthesis Of Disubstituted Bullvalenessupporting

confidence: 53%

“…Reaction of 40 with diazomethane led to the formation of dimethyl bullvalenedicarboxylate (41). 30 Bullvalenedicarbaldehyde (42) was obtained by reduction of the cyano groups in 39 with DIBAL-H. Further reduction of the aldehyde groups in 42 using LiAlH 4 afforded bullvalenediol (43). On the other hand, reaction of 37 with Me 2 CuLi or Ph 2 CuLi gave dimethylbullvalene (44), 25 as a 2.3:3.3:1 mixture of valence, and diphenylbullvalene (45), 24 as a 7.6:5.7:1 mixture of 4,5-, 3,5-, and 3,7-disubstituted isomers.…”

Section: Scheme 16 Preparation Of Dibromobullvalenementioning

confidence: 99%

See 1 more Smart Citation

Synthesis of Bullvalenes: Classical Approaches and Recent Developments

Ferrer

Echavarren

2019

Synthesis

View full text Add to dashboard Cite

The goal of this short review is to provide an overview of the different synthetic methodologies applied along the years for the synthesis of bullvalenes, prototypical fluxional molecules that were key in the understanding of valence tautomerism phenomena. Some interesting applications of these unique shapeshifting compounds are also presented.1 Introduction2 Classical Syntheses of Bullvalenes3 Recent Developments in the Synthesis of Bullvalenes4 Applications of Bullvalenes5 Conclusion

show abstract

Section: Scheme 17 Synthesis Of Disubstituted Bullvalenessupporting

confidence: 53%

Section: Scheme 16 Preparation Of Dibromobullvalenementioning

confidence: 99%

Synthesis of Bullvalenes: Classical Approaches and Recent Developments

Ferrer

Echavarren

2019

Synthesis

View full text Add to dashboard Cite

show abstract

The IntramolecularDiels–Alder Reaction

Ciganek

1984

Organic Reactions

108

View full text Add to dashboard Cite

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.

show abstract

Propellanes VIII. Electrocyclic Reactions of Tetraenic Propellanes

Altman

Babad

Ginsburg

et al. 1969

Israel Journal of Chemistry

View full text Add to dashboard Cite

The electrocyclic reaction sequence of tetraenic propellanes is analogous to that of their parent, cis‐9,10‐dihydronaphthalene as a member of the (CH)10 family. Irradiation of Ia‐e afforded IIa‐e of which IIb and IIc have been isolated. These are the first stable derivatives of tetracyclo [4.4.0.02,10.05,7]deca‐3,8‐diene. Thermal bond‐realignment of IIa‐e led, due to fluxional isomerism in prebullvalene and its derivatives, to prebullvalenes of the III series. Only in the case of the prebullvalene lactone was it possible to observe IVd alongside of IIId in its room terperature NMR spectrum. Irradiation of the prebullvalene ether IIIe afforded a bullvalene ether which at low temperature shows the presence of XIII (R=R=−CH2‐O‐CH2‐) and XV.

show abstract

A New Synthesis of the Bullvalene System

Abstract: structurewhich is supported by the tendency of the cyclopentadienylidene residue to aromatizein fulvenoid phosphacyclohexadienes than is indicated in structure (2).

Cited by 8 publications

References 1 publication

Synthesis of Bullvalenes: Classical Approaches and Recent Developments

Synthesis of Bullvalenes: Classical Approaches and Recent Developments

The IntramolecularDiels–Alder Reaction

Propellanes VIII. Electrocyclic Reactions of Tetraenic Propellanes

Contact Info

Product

Resources

About