Anthracene reaction with

PhS02CH=CHSi(CH3)3 as an acetyiene equivalent in reaction with anthracene,... 

The study of the cycloaddition behavior of l,l-dichloro-2-neopentylsilene, C Si =CHCH2Bu (2) [3], reveals the high polarity of the Si=C bond and a strong electrophilicity. The [4+2] cycloaddition reactions with anthracene (3), cyclopentadiene (4) and fulvenes (5) proceed as expected surprising, however, the Diels-Alder reactions with dienes are of lower activity, like naphthalene (6) and furans (7). 

The close association between metal ions and p-benzoquinones catalyzes their Diels-Alder reactions with anthracenes. The efficiency of the metal cations correlates with their Lewis acidity171. A mechanism proceeding via radical-anions for a [3,3] sigmatropic rearrangement was established172. 

Solid-state reaction of condensed aromatic compounds such as anthracenes, tetracene,pentacene, and naptho [2,3-a] pyrene with C60 under HSVM conditions has also been applied, to yield the corresponding [4+2] cycloadducts [102]. Although the reaction with anthracene afforded the same product (in better yields) than the one when the reaction was carried out in solution [103-105], with pen-tacene it gave an adduct that could not be obtained in solution conditions, in which a pentacene unit was attached to two C60 molecules. Furthermore, reaction with tetracene and naptho[2,3-a]pyrene afforded the expected [4+2] cycloadducts, similar to the case when the reactions were carried out in solution. 

This opens the interesting question of whether upon replacing the hydrogen atoms with suitable substituents it would be possible to realize a linear disilyne with an Si=Si triple bond. As early as 1986 West and coworkers150,151 reported the preparation of a synthon of dimethyldisilyne, bis(7-silanorbornadiene) 163 which, at very high temperature, sets the desired molecule free, as demonstrated, for example, by trapping reactions with anthracene or 3,4-dimethylbutadiene to give the products 164 and 165, respectively (equation 42)152. 

In 1978, Weiler and Brennan [63] reported the use of racemic 4-zso-thiazolin-3-one-l-oxide (54) as a dienophile, the structure of which could be considered to be a cyclic sulfinyl acrylamide. It undergoes facile cycloaddition (temperatures under 60 °C are required) with cyclop entadiene, 2,3-dimethyl-1,3-butadiene and 1,3-cyclohexadiene, to afford only one product in each case (Scheme 28). Reactions with anthracene and hexachloro cyclop entadiene required temperatures above 100°C, and were effectively catalyzed by A1C13. Although the stereochemistry of the obtained adducts was not ascertained, the authors suggest that the major one is the result of an endo-approach, which must be favored on the basis of mechanistic considerations. 

Hydrogermylation of naphthalene, phenanthrene, anthracene and 9-Me-anthracene to form 69-71 proceed in the usual way, in accordance with equations 55-57. Reactions with anthracene and 9-methylanthracene (MA) in benzene solution at inert atmosphere lead to a single isomer of 9-trichlorogermyl-9-methyl-9,10-dihydroanthracene 71 (R = Me) in close to quantitative yield. The structure of 71 shows that protonation takes place in the 10 position of MA in accordance with the orientation effect of the Me group, as happens in the reactions of MA with classical superacids which give a stable <7-complex. ... 

Cycloaddition reactions with anthracene [3], cyclopentadiene [3] and dienes of lower activity, such as naphthalene [4] and furans [6], are well known. In this contribution, we describe the competitive formation of [4+2] and [2+2] cycloaddition compounds resulting from Cl2Si=CHCH2tBu (3) and 6,6-dimethylpentafulvene. 

For instance in benzene and some of its homologs, carbazolyl-N-oxides 246 are detected, in thiophene the heteroanalog radical 247 is formed. On the other hand in furan a 1.4-addition takes place giving product radical 248. Analogously, reaction with anthracene leads to formation of 250. Furthermore reaction of 245 with benzo-nitrile oxides 6 yields benzimidazolyl-N.N -dioxides 249. 

Oxidation of pyridazino[4,5-d]pyridazine-l,4-diol (3) with lead(IV) acetate yields the unstable l,4-dihydropyridazino[4,5-<7]pyridazine-l,4-dione. The formation of this compound could be demonstrated by its Diels-Alder reaction with anthracene or buta-1,3-diene.12... 

Phosphaalkynes also play a prominent role as dienophiles in Diels-Alder reactions hence the X -phosphinines 13 [23] are formed from cyclic 1,3-dienes such as a-pyrone or cyclopen-tadienones by way of extrusion of CO2 or CO, respectively reactions with anthracene provide an access to the phosphabarrelene series [24]. This type of reaction is also of significance for the construction of phosphorus-carbon cage compounds. The same is true for homo-Diels-Alder reactions which, with 2-phosphabicyclo[2.2.2]octa-2,5-diene as reaction partner, lead to the diphosphatetracyclodecenes 14 [25]. Last but not least, ene reactions with phosphaalkynes as enophiles [25] are also valuable for the construction of polycyclic phosphorus-carbon compounds. The reactions of 9 with 2,3-dimethyl-2-butene (- 15) [26, 27] emphasize this behavior. 

Nonracemic a,P-unsaturated p-tolylsulfoxide dienophiles bearing an electron-withdrawing group in the a-position have been employed successfully in Diels-Alder cycloadditions [28,29,94,133], although less frequently than their 3-substituted counterparts. Koizumi and coworkers have reported the use of optically active 2-p-tolylsulfinylacrylate (188) as a chiral dienophile which exhibits high reactivity and diastereoselectivity in cycloaddition reactions with anthracene and cyclopentadiene (Scheme 5.62), affording cycloadducts (189) and (190),... 

The coordination chemistry of this anionic, cyclometallated precatalyst and its derivatives, along with its stoichiometric reactions with anthracene, have been reported by Halpem. On the basis of these studies, a plausible mechanism can be proposed for the hydrogenation of polycyclic arenes by this catalyst. Although kinetic studies of the complete catalytic cycle have not been reported, Halpem s investigation of the stoichiometric reactions of this system provides strong evidence that the reaction occurs by a series of steps involving soluble complexes. 

An efficient catalyst for the hydrogenation of polycyclic arenes, such as anthracene, is derived from an anionic orthometallated hydride ruthen-ate complex that, according to equation (24), reacts with hydrogen to jdeld /ac-[RuH3(PPh3)3], followed by the reaction with anthracene to yield... 

Exp. 49, "Diels-Alder Reaction with Anthracene-9-methanol"... 

EXPERIMENT 48 The Diels-Alder Reaction with Anthracene-9-methanol... 

The Diels-Alder reaction with anthracene-9-methanol from Experiment 48. This compound possesses diastereotopic methylene protons, H, and H. ... 

N,N-Diethyl-m-toluamide (OEF), new procedure Diels-Alder Reaction with Anthracene-9-methanol Identification of Unknowns, revised procedure Competing Nucleophiles in S l and Sj. 2 Reactions Investigations Using 2-Pentanol and 3-Pentanol Friedel-Crafts, more substrates added Aqueous-Based Organozinc Reactions... 

This experiment is a further example of the Diels-Alder reaction. For a discussion of the basic aspects of this reaction see Experiment [14]. In the present case, the central ring of anthracene is shown to possess the characteristic properties of a diene system. Thus, this aromatic compound reacts to form stable Diels-Alder adducts with many dienophiles at the 9 and 10 positions (the two positions on the central ring where new bonds can be made without destroying the aromaticity of the other two rings). Maleic anhydride, a very reactive dienophile, is used here in the reaction with anthracene. Note, that as this reaction is reversible, it is usually best carried out at the lowest possible temperatures consistent with an acceptable reaction rate (see Experiment [14]). 

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