Synthesis of Substituted 1H-Indazoles from Arynes and Hydrazones
摘要:
The 1H-indazole skeleton can be constructed by a [3 + 2] annulation approach from arynes and hydrazones. Under different reaction conditions, both N-tosylhydrazones and N-aryl/alkylhydrazones can be used to afford a variety of indazoles. The former reaction affords 3-substituted indazoles either via in situ generated diazo compounds or through an annulation/elimination process. The latter reaction leads to 1,3-disubstituted indazoles likely through an annulation/oxidation process. The reactions operate under mild conditions and can accommodate aryl, vinyl, and less satisfactorily, alkyl groups.
A Brønsted acid-mediated synthesis of pyrazoles from conjugated hydrazones through a β-protonation/nucleophilic addition/cyclization/aromatization sequence was developed. This protocol utilizing the ambiphilic reactivity of hydrazones enables not only self-condensation but also cross-condensation, affording multisubstituted pyrazoles in high yields, with a broad substrate scope. This sequential reaction
efficient catalyst-free annulation process between propargylicalcohols and hydrazones has been reported. Under the optimized conditions, a wide variety of propargylicalcohols bearing an aromatic group or an aromatic heterocyclic group and hydrazones were well tolerated to afford the corresponding 1,4-dihydropyridazines in moderate to good yields via a Cs2CO3-mediated process.
Supramolecular organic frameworks derived from bromoaryl-substituted dichlorodiazabutadienes via Cl···Br halogen bonding
作者:Namiq G. Shikhaliyev、Abel M. Maharramov、Khanim N. Bagirova、Gulnar T. Suleymanova、Biligma D. Tsyrenova、Valentine G. Nenajdenko、Alexander S. Novikov、Victor N. Khrustalev、Alexander G. Tskhovrebov