Synthesis of methylene-bridged polycyclic aromatic hydrocarbons
作者:ChengXi Yang、Ronald G. Harvey
DOI:10.1021/jo00067a065
日期:1993.7
Synthesis of ketone and alcohol derivatives of methylene-bridged polyarenes, potentially new classes of active metabolites of carcinogenic hydrocarbons
作者:Ronald G. Harvey、Elias Abu-Shqara、Cheng Xi Yang
DOI:10.1021/jo00049a045
日期:1992.11
Methods for the syntheses of bridge ketone and alcohol derivatives of methylene-bridged polyarenes from the parent hydrocarbons are described. The polyarenes investigated include 4H-cyclopenta[def]phenanthrene (1a), fluorene (2a), 7H-benzo[c]fluorene (3a), 4H-cyclopenta[def]chrysene (4a), 11H-Benz[bc]aceanthrylene (5a), 10H-indeno[1,2,7,7a-bcd]pyrene (6a), 11H-dibenzo[bc,l]aceanthrylene (7a), 4H-fluoreno[4,4a,4b,5-abc]anthracene (8a), and 7H-dibenzo[a,g]fluorene (9a). The bridge ketone derivatives are most efficiently synthesized via treatment of the parent hydrocarbons with n-butyllithium and reaction of the resulting anionic intermediates with molecular oxygen. The direct formation of ketones rather than the expected hydroperoxides from reaction of the bridge anions With O2 presumably involves intra- or intermolecular abstraction of a proton from the benzylic site of the intermediate by the peroxy anion leading to loss of hydroxide ion with formation of a carbonyl group. Yields are generally high except in the cases of 1a and 4a; the former affords as the principal product a dimeric alcohol arising from reaction of the anion of 1a with the corresponding ketone lb. The related bridge alcohols am readily obtained in yields of 75-95% by reduction of the crude products from the preceding oxidations with NaBH4.
Electrophilic substitution of methylene-bridged polycyclic aromatic hydrocarbons
作者:Elias Abu-Shqara、Cheng Xi Yang、Ronald G. Harvey
DOI:10.1021/jo00038a016
日期:1992.6
The electrophilic bromination and formylation of the methylene-bridged polycyclic aromatic hydrocarbons 11H-benz[bc]aceanthrylene (2), 4H-cyclopenta[def]chrysene (3), 13H-dibenz[bc,l]aceanthrylene (4), and 4H-benzo[b]cyclopenta[mno]chrysene (5) were investigated. All reactions proceeded with high regioselectivity to afford predominantly a single major isomeric product. The sole exception was bromination of 3 which gave a small amount of a second isomeric product. The sites of electrophilic substitution were correlated with theoretical predictions from semiempirical molecular orbital calculations using the MNDO method, The observed sites of electrophilic substitution were in excellent agreement with the theoretical predictions in the cases of 2-4. However, in the case of 5, substitution took place in the 6-position, whereas the site predicted to be most reactive is the 5-position. In addition, the aryl aldehyde products were converted into the corresponding methyl derivatives for studies of their potential carcinogenicity.
Sythesis of methylene-bridged polyarenes
作者:ChengXi Yang、Ronald G. Harvey
DOI:10.1016/s0040-4020(01)92265-3
日期:1992.1
synthetic approaches are lacking. Convenient syntheses of a series of methylene-bridge polyarenes are now described. These syntheses are based upon the prototype hydrocarbon cyclopenta[def]phenanthrene (1) which contains a pre-existing methylene bridge. Polyarenes prepared include 13H-dibenz[bc,l]aceanthrylene (3), 4H-cyclopenta[pqr]picene (5) 4H-benzo[b]cyclopenta[mno]chrysene (6), 13H-indeno[2,1,7-qra]naphthacene
First Examples of Stable Arenium Ions from Large Methylene-Bridged Polycyclic Aromatic Hydrocarbons (PAHs). Directive Effects and Charge Delocalization Mode
作者:Kenneth K. Laali、Takao Okazaki、Ronald G. Harvey
DOI:10.1021/jo0100603
日期:2001.6.1
persistent arenium ions from large methylene-bridged PAHs (mostly 22pi six-fused ring systems). Low-temperature protonation (FSO(3)H/SO(2)ClF) and model nitration (with HNO(3)/HOAc or NO(2)(+) BF(4)(-)) were used as mimic reactions for generation of biological electrophiles. The site(s) of protonation (and nitration) were determined as a function of PAH structure. Chargedelocalization mode in the resulting