Processing of o-Halobenzoates by Toluene Dioxygenase. The Role of the Alkoxy Functionality in the Regioselectivity of the Enzymatic Dihydroxylation Reaction
摘要:
In order to investigate the relationship between the size of a substituent on the aromatic substrate and its directing effect on the dihydroxylation, a series of 2-halobenzoates was synthesized and subjected to metabolism by toluene dioxygenase in preparative-scale fermentation cultures of Escherichia coli JM109 (pDTG601A). Larger ester substituents were shown to have a greater directing effect on the dihydroxylation reaction. Furthermore, significant increases in regioselectivity were observed using propargyl substituents, relative to the use of any other ester substituent. The selectivity and the product ratios are reported for o-fluoro-, o-chloro-, o-bromo-, and o-iodobenzoate esters (methyl, ethyl, n-propyl, allyl, and propargyl). Experimental and spectral data, as well as absolute stereochemistry, are provided for all new compounds.
Enantioselective Total Synthesis and Biological Evaluation of (+)-Kibdelone A and a Tetrahydroxanthone Analogue
作者:Dana K. Winter、Mary Ann Endoma-Arias、Tomas Hudlicky、John A. Beutler、John A. Porco
DOI:10.1021/jo401169z
日期:2013.8.2
The total synthesis of kibdelone A has been accomplished via In(III)-catalyzed arylation of a heterocyclic quinone monoketal and iodine-mediated oxidative photochemical electrocyclization for construction of the ABCDring moiety. Enzymatic dihydroxylation of methyl 2-halobenzoate substrates was employed for synthesis of activated 2-halo-cyclohexene F-ring fragments. A one pot oxa-Michael/Friedel–Crafts
Kibdelone A 的全合成是通过 In(III) 催化的杂环醌单缩酮的芳基化和碘介导的氧化光化学电环化来构建 ABCD 环部分完成的。2-卤代苯甲酸甲酯底物的酶促二羟基化用于合成活化的 2-卤代环己烯 F 环片段。一锅oxa -Michael/Friedel-Crafts 工艺允许获得第一个简化的 kibdelones 的 DEF 环类似物。