Highly Diastereoselective Synthesis of Nucleoside Adducts from the Carcinogenic Benzo[<i>a</i>]pyrene Diol Epoxide and a Computational Analysis
作者:Mahesh K. Lakshman、John C. Keeler、Felix N. Ngassa、John H. Hilmer、Padmanava Pradhan、Barbara Zajc、Kathryn A. Thomasson
DOI:10.1021/ja063902u
日期:2007.1.1
diastereoselective dihydroxylation wherein phenylboronic acid was a water surrogate. The resulting boronate ester was converted to a tetraol derivative in which two of the four hydroxyl groups (trans 7, 8) were protected as benzoate esters while the remaining two (cis 9, 10) were free. The cis glycol entity was then subjected to a reaction with 1-chlorocarbonyl-1-methylethylacetate to yield an intermediate chloro
Chloride Ion Catalyzed Conformational Inversion of Carbocation Intermediates in the Hydrolysis of a Benzo[<i>a</i>]pyrene 7,8-Diol 9,10-Epoxide
作者:Lanxuan Doan、Haruhiko Yagi、Donald M. Jerina、Dale L. Whalen
DOI:10.1021/ja020436+
日期:2002.12.1
the cis/trans ratio of tetrols from the reaction of the carbocation intermediate from the hydrolysis of chlorohydrin 5 is different than the cis/trans tetrol ratio from the acid-catalyzed hydrolysis of diol epoxide 1, which hydrolyzes via a carbocation with the same connectivity as that formed in the hydrolysis of 5. To rationalize these results, it is proposed that the S(N)1 reaction of chlorohydrin
Halide Effects in the Hydrolysis Reactions of (±)-7β,8α-Dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo- [<i>a</i>]pyrene
作者:Bin Lin、Lanxuan Doan、Haruhiko Yagi、Donald M. Jerina、Dale L. Whalen
DOI:10.1021/tx9701743
日期:1998.6.1
resulting in the formation of a trans-halohydrin. Reaction of DE-2 in these halide solutions at pH < ca. 5 occurs by rate-limiting carbocation formation, followed by capture of the intermediate carbocation by halide ion. The relative magnitudes of the rate constants for reaction of the intermediate carbocation with halide ions are estimated from product studies. The halohydrins are unstable intermediates
已在1:9二恶烷水中测定了(+/-)-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-四氢苯并[a] py(DE-2)的反应速率在4-13的pH范围内含有1.0 M KCl,0.5 M KBr和0.1 M NaI的溶液。这些pH速率分布要比DE-2在0.2 M NaClO4溶液中的反应要复杂得多,部分解释是由卤离子在中等pH值下以亲核体形式攻击二醇环氧化物而形成反式的。 -卤代醇。DE-2在这些卤化物溶液中在pH 12时,由于HO-与DE-2的二级反应,DE-2的反应速率增加。
New Insights on the Mechanisms of the pH-Independent Reactions of Benzo[<i>a</i>]pyrene 7,8-Diol 9,10-Epoxides
作者:Lanxuan Doan、Bin Lin、Haruhiko Yagi、Donald M. Jerina、Dale L. Whalen
DOI:10.1021/ja004359z
日期:2001.7.1
10-tetrahydrobenzo[a]pyrene (1) and (+/-)-7beta,8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (2) in water and dioxane-water mixtures have been determined over a pH range wider than that of earlier studies. This study provides additional insight on the mechanisms of the pH-independent reactions of 1 and 2. The rate profile for reaction of 1 shows acid-catalyzed hydrolysis at pH <5, a