Angular rings

Thiazolo[5,4-/]quinoline 23 was prepared in 1949 starting from 6-aminobenzo-thiazole using Skraup reaction conditions glycerol, sodium 3-nitrobenzenesulfo-nate, and 78% sulfuric acid and heating at 110°C for 12 hours. Angular ring fusion... 

Figure 8. Mutagenicities of BA, BaAcr, and BcAcr angular ring tetrahydroepoxides in Sj typhimurium TA 98 and TA 100. (Adapted from Ref. 29 and unpublished results from these laboratories.)...

Unhindered angular ring trans-dihydrodiols such as trans-7,8-dihydro-... 

In contrast, the fluorine atom at the peri-position of 12F-5-methylchrysene influences dihydrodiol formation in the adjacent angular ring. Whereas the ratio of 5-MeC-7,8-diol to 5-MeC-l,2-diol in mouse epidermis was 1 1, 2 hr after topical application of [%] 5-MeC, the ratio of 12F-5-methylchrysene-7,8-diol to 12F-5-methylchrysene-1,2-diol was 68 1. In contrast to 5-MeC, the metabolites formed from 12F-5-methylchrysene in mouse skin resulted almost exclusively from oxidation at the 7,8-bond (57). Thus, metabolic switching to the less tumorigenic 7,8-dihydrodiol appears to be the basis for the lower tumorigenicity of 12F-5-methylchrysene compared to 5-MeC. 

The cyclization of N-(4-oxoquinazolin-2-yl)aminomethylenemalonate (1070) by heating in diphenyl ether at 240°C for 10 min occurred at position 1 to afford the angular ring system (1071) in 81% yield (89JHC161). Cycliza-... 

The values in Table 23 show that in unsubstituted benz[a]anthracene the ion A has the greater basicity. On substitution of the angular ring, the basicity increase is approximately equal. Ion A is favoured for substituents in the vicinity of the 7-position (positions 5, 6, 8, 9), and ion B is favomred by substituents in the vicinity of the C-atom 12 (10... 

The structures of the compounds were verified by H NMR spectroscopy. Two doublets of benzene ring protons (7 = 9 Hz) characteristic of mutual ott, ti-positions indicated angularly ring-fused structures. The shifts of NMR peaks and the features of the IR spectra (containing deformed out-of-plane vibrations at 800 cm ) were characteristic of 1,2,3,4-tetrasubstitution and so also confirmed the angular ring fusion. 

Class C. Phenanthrene and molecules containing similar angular ring systems. Under this category come the following molecules ... 

C. Phenanthrene and Molecules Containing Similar Angular Ring Systems... 

In the case of diols such as n-propanel,3-diol, dibromosiloxenes react with only one OH group, in accordance with the angular ring structure in which one bromine atom is on one side and the second on the other side of the ring. Bridge formation is therefore impossible. 

The increased stabilization upon thienoannulation as compared to benzo-annulation may be caused by the more effective stabilization of the positive charge, by diminished angular ring strain, and by limited peri interactions between hydrogen atoms (due to the heteroatoms) and hence by nearly perfect planarity. 

C-3 of the naphthalene nucleus that controls the electrophilic ring-closure of the vinyl ketene intermediate moreover, the degree of aromaticity of the angular rings in the phenanthrene skeleton exceeds that in the anthracene analogues. This regioselectivity observed in the benzannulation of chromium carbenes is paralleled by results observed for 2-naphthyl cyclo-butenones [77] and for the palladium-catalyzed cyclocarbonylation of 2-naphthyl allyl acetates [78]. 

Some methylbenz[c]acridines are strongly carcinogenic, whereas their derivatives are inactive [18-22]. Previously, we reported on the relationship between the carcinogenic activity of benz[a]acridines [30-40] and the zr-spin density [25] and the relationship between the carcinogenic activity of benz[a]acridines [30-41] and the values of the resonance energy per. v-elecIron (REPE) [26,27]. Consequently, by clockwise rotation on an angular ring or naphthalene moiety, the distribution of the zr-spin dens-... 

Tetrahydronaphthalene oxide 59a has two conformations, 63a and 63b. From analysis of vicinal H-C-C-H coupling constants in the H NMR spectrum of 59a, it was concluded that conformation 63a, in which the bonds of the angular ring have fewer eclipsing interactions than those of 63b, is the more stable.67 This conclusion is supported by quantum chemical calculations in which conformation 63a is calculated at the B3LYP/6-31G level of theory to be >4kcalmol 1 more stable than 63b in the gas phase.49... 

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