Visible Light-Induced Cascade Cyclization of 3-Aminoindazoles, Ynals, and Chalcogens: Access to Chalcogen-Containing Pyrimido[1,2-b]-indazoles

Abstract

A direct cascade cyclization of 3-aminoindazoles, ynals, and accessible chalcogens facilitated by visible light has been developed. A series of fluoroactive selenium/tellurium-substituted pyrimido­[1,2-b]-indazoles were easily accessed in moderate to good yields with a broad scope. Furthermore, we surveyed the spectral properties of selenide pyrimido­[1,2-b]-indazoles prepared by this method.

Three-Component Carbosilylation of Alkenes by Merging Iron and Visible-Light Photocatalysis

“…On the basis of the above experimental outcome and literature reports, − we have proposed a plausible mechanistic path of this heteroaryl silylation of olefins as illustrated in Scheme . Initially, a single-electron transfer (SET) occurs from iron­(II) to the excited state of EY (EY*) and generates photocatalyst radical anion EY •– and iron­(III) .…”

“…Recently, visible-light photocatalysis has become an impressive tool in organic synthesis . In this realm, the merger of transition-metal catalysis and visible-light photoredox catalysis offers an exciting opportunity to perform the organic transformations under mild conditions. , In continuation of our efforts in the field of visible-light-mediated functionalization of imidazopyridine, herein we report a three-component carbosilylation of alkenes with imidazoheterocycles and silanes by merging visible-light photocatalysis and iron­(II) catalysis (Scheme ).…”

Deconstructive Cycloaromatization Strategy towards N,O-Bidentate Ligands and Their Four-Coordinate Organoboron Complexes

“…We have long been committed to developing new methods to construct nitrogen-containing heterocyclic derivatives. [69][70][71][72][73] Thus, easily available 2-phenylindolizine and diphenylcyclopropenone were chose as the model substrates to conduct the reaction under 120 o C in DCM for 18 h (Table 1). Surprisingly, the sequence deconstructive recycloaromatization product was secured with a prominent yield (95%) without any catalysts and additives (Table 1, entry 1).…”

Multicomponent reactions and photo/electrochemistry join forces: atom economy meets energy efficiency

“…In a recent work, Zhou et al reported the use of diselenides and digermanides in the preparation of pyrimido[1,2-b]indazoles. 186 Organoselenium compounds are attracting great interest in the pharmaceutical field, and novel approaches for the introduction of selenium atoms are being investigated. Conventional methods involve the electrophilic difunctionalization of unsaturated bonds and require the use of oxidants together with activation by either acid or Lewis bases.…”