Here
we have demonstrated a visible-light-mediated metal-free organic-dye-catalyzed
dehydrogenative N-insertion leading to highly substituted imidazoles
and privileged dihydroisoquinoline-based imidazole derivatives via
C(sp3)–H and C(sp2)–H bond functionalization.
A sustainable, convenient, metal-free azidation/C–H aminative
cyclization approach in the absence of stoichiometric oxidants is
presented. This protocol involves a rare photoinduced iminyl radical
as a key intermediate for the “N” insertion.
Enantioselective desymmetrization of prochiral 1,3cyclodiketones is the most convenient and highly desired transformation to access densely functionalized, enantiomerically enriched scaffolds with multiple chiral centers. In recent years, organocatalysis has made significant progress in this research area along with other traditional metal-or enzymecatalyzed reactions. This mini-review provides an overview of the recent developments in the domain of organocatalytic enantioselective desymmetrization along with a brief discussion about future perspectives.
A copper-catalyzed intramolecular α-C–H amination has been developed for the synthesis of quinazolin-4(3H)-one derivatives from commercially available isatoic anhydride and primary and secondary benzylamines via ring-opening cyclization (ROC). This method shows good functional group tolerance and allows access to a range of 2-aryl, 2-alkyl, and spiroquinazolinone derivatives. However, 2-methylquinazolin-4(3H)-one was synthesized from 2-amino-N-isopropylbenzamide by C–C bond cleavage, and N-benzyl-2-(methylamino)benzamide afforded 1-methyl-2-phenylquinazolin-4(1H)-one along with 2-phenylquinazolin-4(3H)-one by N–C bond cleavage for aromatization. It is the first general method to construct the potentially useful 2-methylquinazolin-4(3H)-one by copper-catalyzed intramolecular C–H amination. Also this ROC strategy has been successfully applied to the synthesis of quinazolinone alkaloid rutaecarpine.
A branching double-annulation cascade (BDAC) strategy for diverse and complex fused THIQ scaffolds via a highly reactive iminium-induced one-pot double-cyclization sequence involving Pictect-Spengler-type cyclization has been developed for the first time. The salient features of this protocol are that it allows direct and rapid access to unprecedented diverse fused THIQ skeletons, is metal/catalyst free, has a cleaner reaction profile, provides good to excellent yields, and is a convenient approach. This catalyst-free domino process facilitates the double annulation with a variety of scaffold building agents via two C-N and one C-X (X = C, N, O) bond formation in a single step under uniform reaction conditions. Furthermore, we reveal an unusual dual BDAC sequence leading to N-N-linked isoquinoline dimer.
We herein report the design and synthesis of three new indole and carbazole based dyes (D1, D2 and D3) with a donor-(pspacer)-acceptor (D-p-A) configuration with N-methylindole and carbazole as donors, barbituric acid and N-acyloxindole as acceptors/anchoring groups. DFT calculations of three dyes D1, D2 and D3 by using the B3LYP/6-31 + G(d) basis set provided the optimized ground-state molecular geometries. Theoretical light harvesting efficiencies (LHE), of all the dyes were studied by time dependent density functional theory (TD-DFT) method in order to shed the light on how the p-conjugation order influence the performance of the dyes. Along with the TD-DFT calculations photophysical and electrochemical properties of the dyes were investigated by UV spectroscopy and cyclic voltammetry (CV), which indicates that D3 could show the best performance among the three dyes.[a] S.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.