Base‐Promoted Synthetic Transformation of 4H‐Chromenes into Dihydrobenzofurans and Bispyrazolospirocyclopropanes via Intramolecular Cyclization

Abstract

A novel protocol is accomplished for transformation of 2amino-7,7-dimethyl-5-oxo-4-phenyl-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile (1) into dihydrobenzofuran-2,2-dicarbonitriles (2) by reacting with N-chlorosuccinimide in presence of base at ambient temperature. On the other hand, same reaction with6-amino-3-methyl-1,4-diphenyl-1,4-dihydropyrano [2,3-c]pyrazole-5-carbonitrile (3) and NCS, surprisingly lead to formation of bispyrazolospirocyclopropanes (5). Simple reaction conditions, excellent yields and high compatibility are the advantages of this protocol.Reaction Conditions: 3(1.0 mmol),NaOH(1.0 mmol),NCS (1.0 mmol), water, ambient temperature. [b] Isolated yield and reaction time. Scheme 7. plausible mechanism for compound 2&5.

Interfacial Engineering of Zn Metal via a Localized Conjugated Layer for Highly Reversible Aqueous Zinc Ion Battery

“…This indicates that the introduction of Zn(OTf) 2 salt accelerates the cyclization process of PAN. The strong Lewis acidity of Zn(OTf) 2 can act as a catalyst to facilitate the intramolecular cyclization, [10] which is consistent with previous reports on the using of catalyst to reduce the cyclization temperature of PAN. [9b,11] We further use density functional theory (DFT) calculation to further understand the underlying mechanism.…”