Benzene fused

BENZENE-FUSED HETEROCYCLES CONTAINING TELLURIUM, SELENIUM AND SULPHUR... 

Hashimoto and co-workers, on the other hand, studied the intramolecular reaction between cyclic carbonyl yield and dimethyl acetylenedicarboxylate (DMAD) (Equation (14)). With dirhodium(ii) tetrakis[A-benzene-fused phthaloyl-(A)-valinate] [Rh2(WBPTV)4] 104, high enantioselectivity (68-92% ee) was achieved over a range of diazo substrates.The high level of enantiocontrol provided conclusive evidence that chiral Rh(ii) catalyst is associated with the ylide in the cycloaddition step. 

The coumarins are benzene-fused derivatives of pyran-2-ones. Many of the coumarins have interesting uses as drugs and antibiotics. The relatively less common isocoumarins and arylcoumarins are also members of the pyran-2-one family. 

Stefinovic, M. and Snieckus, V. 1998. Connecting directed ortho metalation and olefin metathesis strategies. Benzene-fused multiring-sized oxygen heterocycles. First syntheses of Radulanin A and Heliannane. J. Org. Chem. 63, 2808-2809... 

In each of the five sections of Chapter 3, the chemistry is reviewed in the following order (1) Reactivity of aromatic rings (thermal reactions not involving reagents, substitutions at carbon, additions to nitrogen, metallations) (2) Reactions of nonaromatic compounds (this enormous area, which overlaps extensively with nonheterocyclic chemistry, is reviewed with emphasis on the heterocyclic aspects) (3) Reactions of substituents (with emphasis on situations in which substituents behave somewhat differently when attached to a heterocycle note that for benzene-fused heterocycles, the benzene ring is treated as a substituent). 

Aurones (Phe C40(=0)=CH-Phe). Aurones (2-benzylidenebenzofuranones) derive from oxidation and cyclization of chalcone precursors to yield the corresponding benzofura-none (benzene fused with a five-membered furanone ring) Phenyl-CO- CH=CH—Phenyl + O2 — Benzofuranone = CH-Phenyl. Various aurones inhibit iodothyronine deiodinase, namely (numbering 1-9 in the bicyclic benzofuranone and 1 -6 in the benzylidene phenyl) aureusidin (4,6,3, 4 -tetrahydroxyaurone), bracteatin (4,6,3, 4, 5 - pentahydroxyaurone), maritimetin (6,7,3, 4 -tetrahydroxyaurone) and sulfuretin (6,3, 4 -trihydroxyaurone). 

To confirm this finding based on the degree of the benzene ring C-C distortion, the magnetic susceptibility anisotropies and the relative energies for the benzene-fused five-membered heterocycles have been computed (Table 68). A similar approach was used by Schleyer et al. <1995AGE337> to evaluate the aromaticity of five-membered heterocycles using the ab initio methods. 

Benzene-fused seven- and eight-membered ring heterocycles such as I are important compounds in the pharmaceutical industry owing to their effect as cardiovascular agents. Their complex chemistry ought to be, therefore, of some relevance to anyone interested in this broad field of organic chemistry. The present case is an example of the versatile chemistry of these heterocycles. 

Speculative A, unsaturated monocycle B, monobenzo derivative of A C, dibenzo derivative of A D, tribenzo derivative of A. Benzene fused at the double-bond position. 

The majority of the derivatives with benzene fused to a seven-membered ring are of structural type (IX). Since these may be viewed as symmetrical derivatives, the most convenient synthetic routes are those of the direct reaction of an appropriately substituted aryl derivative with a bifunctional organometallic. 

Basak, A. Mandal, S. Kumar Das, A. Bertolasi, V. Benzene fused mono-cyclic enediynyl amides synthesis, reactivity and DNA-cleavage activity in comparison to thc corresponding sulfonamides. Bioorg. Med. Chem. Lett. 2002, 12, 873-877. 

A synthesis for the benzene fused heterocycles of the type 10 and 11, which can be also applied to other fused heterocycle 12 would involve disubstituted starting compounds of the type 13 and 14 respectively, which by standard methods can be converted... 

Cyclisation of the allylic acetate (275), by treatment with thionyl chloride in pyridine and sodium hydride in refluxing xylene, was accompanied by dehydrogenation to produce the benzene-fused system (276). ... 

The classic Diels-Alder reaction continues to be applied to steroidal dienes and has been used to prepare benzene-fused compounds (277) (from 6-methylene testosterone ), and (278) and (279) [from the furano-steroid (217) ] and adducts between A -dienes and methyl acrylate, hexafluorobut-2-yne, dimethylacetylene dicarboxylate, and methyl propiolate have been obtained. In this last reaction the mono-adduct (280) was accompanied by a diadduct, assigned the structure (281), which arises from homo-conjugate Diels-Alder addition and which appears to be the first example of homo-conjugate addition to a substituted bicyclo[2,2,l]heptadiene. The diadduct was also obtained in good yield by treatment of the mono-adduct with more methyl propiolate. 

Transition-metal-catalyzed [2 + 2 + 2]-cycloaddition of alkynes, so-called cyclotrimerization, has been widely investigated as a powerful tool to construct benzene rings.117 Cyclotrimerization of the amino-dialkynes and dialkynyl ethers 109 with alkynes provides various kinds of benzene-fused aza- and oxa-heterocyclic compounds 111 (Scheme 39, route a).118 The key intermediate for the [2 + 2 + 2]-cycloaddition is the metallacyclopentadienes 110, as men-... 

Mikami and Ohmura reported that the cycloaddition of isobenzofuran 138, which was generated from the lactol methyl ether 136 upon treatment with palladium(O) catalyst, with dimethyl acethylenedi-carboxylate gave the benzene-fused oxanorbornene 137 (Scheme 48).124... 

Cinnoline 1 (benzo[c]pyridazine), phthalazine 2 (benzo[ /]pyridazin), quinazoline 3 (benzo[annulated systems, only phenazine 5 (dibenzopyrazine) will be discussed. 

The benzene-fused analogue (189) has also been prepared in 14% yield by a Wittig reaction <72JA7087>. This could be oxidized to the sulfoxide and sulfone by H2O2 in acetic acid. Neither the sulfoxide nor the sulfone showed any tendency to dimerize by a Diels-Alder mode. This is in contrast to simple thiophene 5-oxides, and is probably because any such dimerization would result in the formation of a benzocyclobutadiene structure. Photolysis of the sulfone leads to a head-to-head dimer. The thiophene ring in (189) is very reactive. Bromination with pyridinium bromide... 

Some of the important benzene-fused five-membered heterocycles are indole, benzofuran, benzothiophene, benzimidazole, benzoxazole, and benzothiazole. The numbering of these heterocycles is shown below ... 

Chief among the six-membered heterocycles, pyridine and its benzene-fused derivative quinoline are most ubiquitous. Pyrazine and its benzene-fused analogue, quinoxaline, also play an important role in heterocyclic chemistry. 

Rh2(S-BPTV)4 Dirhodium(II) tetrakis[N-benzene-fused-phthaloyl-(S)-valinate]... 

Another successful catalytic enantioselective 1,3-dipolar cycloaddition of Qf-diazocarbonyl compounds using phthaloyl-derived chiral rhodium(II) catalysts has been demonstrated [ill]. Six-membered ring carbonyl ylide formation from the a-diazo ketone 80 and subsequent 1,3-cycloaddition with DMAD under the influence of 1 mol % of dirhodium(II) tetrakis[M-benzene-fused-phthaloyl-(S)-phenylvaline], Rh2(S-BPTV)4 101 [112], has been explored to obtain the cycloadduct 102 in up to 92% ee (Scheme 31). 

Benzene-fused sulfolenes were found to be readily alkylated with alkenyl side-chains and the alkylated products, when heated, were converted to o-quinodimethanes by SO2 extrusion. These spontaneously reacted in an intramolecular Diels-Alder fashion, to produce tricyclic systems with good stereochemical control. The methodology was exploited in a short and efficient synthesis of ( )-estra-l,3,5(10)-triene-17-one (228) [89] (Scheme 6.71). Sulfolene (223) was first alkylated with tosylate (224) to provide (225) in good yield. After ketal removal, (226) was thermolysed to provide estratriene (228) in 85% yield, via o-quinodimethane (227). The compound was contEuninated by 5-7% of the C-9 epimer, which was easily removed by recrystallization. 

Hashimoto has reported the enantioselective domino carbonyl yUde formation/l,3-dipolar cycloaddition reaction of a range of a-diazo ketones 185 with various aromatic aldehydes 92, promoted by the chiral Rh(II)-tetrakis[N-benzene-fused-phthaloyl-(S)-valinate] complex (184). The present reaction afforded the corresponding bicyclic cycloadducts 186 in good yields and enantioselectivities. The exo diastereomer 186 was diastereoselectively generated as a single product in almost all the cases (Scheme 11.40) [61]. 

The capacity factors k ) for 32 benzene, fused benzene, and phenol derivatives (including alkyl-, chloro-, bromo-, and nitro-substituted) were obtained under various isocratic elution conditions on a C g column (A = 254 nm or 282nm) over the range of 70-100% methanol (in 10% increments) in wato [107]. The k values for a smaller set of these analytes were tabulated for mobile phase compositions ranging from 60/40 to 0/100 methanol/water. A complete set of tabulated results was presented and provides an excellent basis from which to begin method development. 

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