- Palladium-Catalyzed Oxidative C–H Alkoxycarbonylation of Arenes with Alkylcarbazates Directed by N-Heterocyclic Substituents
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With alkyl carbazates as the green ester source, a novel palladium-catalyzed oxidative free radical carbonylative transformation of the C–H bond on aromatic rings to produce esters has been developed. Good yields of the corresponding products have been obtained with wide functional group tolerance and excellent regioselectivity. A variety of alkyl carbazates are found to be suitable reactants for the ortho-alkoxycarbonylation on the aromatic ring.
- Yogesh Kumar, Gujjenahalli Ramalingaiah,Begum, Noor Shahina
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supporting information
p. 4698 - 4704
(2020/07/04)
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- 1,2-Diazacyclopentane-3,5-diyl Diradicals: Electronic Structure and Reactivity
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Localized singlet diradicals are key intermediates in bond homolysis. A thorough study of the reactive species is needed to clarify the mechanisms of the homolytic bond cleavage and formation processes. In general, the singlet diradicals are quite short-lived because of the fast radical-radical coupling reactions. The short-lived characteristic has retarded the thorough study on bond homolysis. In this study, a new series of long-lived singlet diradicals, viz., 1,2-diazacyclopentane-3,5-diyl, were identified, and their electronic structures and novel reactivities were thoroughly studied using laser-flash photolysis (LFP), product analysis, and computational studies. A direct observation of the thermal equilibration (fast process) between the singlet diradicals and the corresponding ring-closing compounds was undertaken on the submicrosecond time scale. The solvent and substituent effects on the equilibration constant and rate constants for the ring-closing reaction and ring-opening reaction clarify the novel nitrogen-atom effect on the localized singlet 1,3-diyl diradicals. Two types of alkoxy-migrated compounds, 9 and 10, were isolated with high yields as the final products. Crossover, spin-trapping, and LFP experiments for the formation of alkoxy-group migration products (i.e., 9 versus 10) revealed the unique temperature effect on the product ratio of the two types of alkoxy-migration products. The temperature-insensitive intersystem crossing process (slow process, millisecond time scale) was found to be a key step in the formation of 9, which is an entropy-controlled pathway. An intramolecular migration process was identified for the formation of 10 that was accelerated by a polar solvent in an enthalpy-controlled process. This unique heteroatom effect has opened up a new series of localized singlet diradicals that are crucial intermediates in bond homolysis.
- Yoshidomi, Shohei,Abe, Manabu
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supporting information
p. 3920 - 3933
(2019/03/07)
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- Synthesis of 6-carboxylated phenanthridines by oxidative alkoxycarbonylation-cyclization of 2-isocyanobiphenyls with carbazates
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An iron-catalyzed synthesis of 6-carboxylated phenanthridines starting with readily prepared isocyanides and carbazates was developed. Reactions occurred via addition of alkoxycarbonyl radicals to the isocyanide group and subsequent intramolecular cyclization.
- Wang, Gao,Chen, Shan-Yong,Yu, Xiao-Qi
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supporting information
p. 5338 - 5341
(2015/01/09)
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- Aryl substituted 7-oxabicycloheptane compounds, useful in inhibiting platelet aggregation
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7-Oxabicycloheptane and prostaglandin analogs are provided having the structural formula STR1 and including all stereoisomers thereof. The compounds are cardiovascular agents useful, for example, in the treatment of thrombolytic disease.
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- 7-Oxabicycloheptane hydrazone prostaglandin analogs useful in treating thrombolytic diseases
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7-Oxabicycloheptane hydrazone prostaglandin analogs are provided having the structural formula STR1 and including all stereoisomers thereof. pa The compounds are cardiovascular agents useful, for example, in the treatment of thrombolytic disease.
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