158399-76-9Relevant articles and documents
Charge-transfer-directed radical substitution enables para-selective C-H functionalization
Boursalian, Gregory B.,Ham, Won Seok,Mazzotti, Anthony R.,Ritter, Tobias
, p. 810 - 815 (2016/07/29)
Efficient C-H functionalization requires selectivity for specific C-H bonds. Progress has been made for directed aromatic substitution reactions to achieve ortho and meta selectivity, but a general strategy for para-selective C-H functionalization has remained elusive. Herein we introduce a previously unappreciated concept that enables nearly complete para selectivity. We propose that radicals with high electron affinity elicit arene-to-radical charge transfer in the transition state of radical addition, which is the factor primarily responsible for high positional selectivity. We demonstrate with a simple theoretical tool that the selectivity is predictable and show the utility of the concept through a direct synthesis of aryl piperazines. Our results contradict the notion, widely held by organic chemists, that radical aromatic substitution reactions are inherently unselective. The concept of radical substitution directed by charge transfer could serve as the basis for the development of new, highly selective C-H functionalization reactions.
Substituted azolone derivatives
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, (2008/06/13)
The use for the manufacture of a medicament for treating Helicobacter-related diseases of a compound of formula STR1 a pharmaceutically acceptable acid addition salt or a stereochemically isomeric form thereof, wherein X and Y each independently are CH or N; R1, R2 and R3 each independently are hydrogen or C1-4 alkyl; R4 and R5 each independently are hydrogen, halo, C1-4 alkyl, C1-4 alkyloxy, hydroxy, trifluoromethyl, trifluoromethyloxy or difluoromethyloxy; Z is C=O or CHOH; and Ar is phenyl optionally substituted with up to three substituents selected from hydroxy, C1-4 alkyl, C1-4 alkyloxy, halo, trifluoromethyl, triC1-4 alkylsilyloxy, nitro, amino and cyano or pyridinyl substituted with hydroxy or C1-4 alkyloxy; and --A-- is a radical of formula STR2
