Ambident reactivity of 5-aminopyrazoles towards donor-acceptor cyclopropanes
Anna E Vartanova1, Irina I Levina2, Nina K Ratmanova1,3
1N. D. Zelinsky Institute of Organic Chemistry Russian Academy of Sciences, Leninsky pr. 47, Moscow 119334, Russian Federation. trush@ioc.ac.ru.
Abstract:
Lewis acid-catalysed reactions of donor-acceptor cyclopropanes with 1,3-disubstituted 5-aminopyrazoles were investigated. Under catalysis with gallium(III) chloride, products of the three-membered ring opening via a nucleophilic attack of the exocyclic amino group were obtained in a chemoselective manner. Oppositely, in the presence of scandium(III) triflate, products of either N-alkylation or C(4)-alkylation, or a mixture of both were formed. The products of the C(4) alkylation were transformed in one step into tetrahydropyrazolo[3,4-b]azepines that are attractive for medicinal chemistry and pharmacology.
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