[Ag(PcL)]‐Catalysed Domino Approach to 6‐Substituted Benzoxazino Isoquinolines

Abstract

In this paper, we describe a new silver catalysed domino approach to 6‐substituted benzoxazino isoquinolines starting from 2‐alkynylbenzaldehydes and 1‐substituted‐(2‐aminophenyl)methanols. The strategy is characterized by good reaction yields, and can be performed at room temperature as well as under heating (conventional or dielectric) in different reaction times. Best results have been obtained by using silver complexes of macrocyclic pyridine‐containing ligands (PcL) as catalysts. The stereoselectivity of the transformation has been investigated by using chiral reaction partners and chiral catalysts, but unfortunately, modest stereoselectivities have been achieved. On the other hand, this approach represents an alternative synthetic strategy for the preparation of 6‐substituted benzoxazino isoquinolines, which are the key scaffold of some compounds endowed of biological activity.

Recent progress in the chemistry of 12-membered pyridine-containing tetraazamacrocycles: from synthesis to catalysis

“…Next, a related domino reaction using the same aldehydes along with 2-(hydroxymethyl)anilines cleanly afforded benzoxazino isoquinoline derivatives, a biologically relevant polycyclic scaffold, in high yields (Scheme 30). 110 The synthesis of compound 120 from aldehyde 118 and aniline 119 is shown herein as an illustrative example for a transformation which, again, showed a broad scope. In contrast, attempts to perform asymmetric transformations provided only modest results.…”

Coinage Metal-Catalyzed Asymmetric Reactions of ortho-Alkynylaryl and Heteroaryl Aldehydes and Ketones

“…Traditionally, silver complexes have been extensively exploited in organometallic transformations implying ortho -alkynylaryl and heteroaryl aldehydes and ketones, as pioneered by Belmont’s and Abbiati’s groups [ 8 , 27 , 28 , 29 , 39 ]. The development of enantioselective transformations involving silver complexes has been described by Terada’s group in 2014 [ 48 ].…”

“…Other metals such as Pd [ 19 , 20 , 21 , 22 ], Ru [ 23 ], Au [ 24 , 25 , 26 , 27 ], Ag [ 28 , 29 , 30 ], Cu [ 31 , 32 ], and electrophiles have then been engaged, and two pathways have been identified depending on the nature of the catalyst, 5- exo-dig and 6- endo-dig , resulting in various cyclic products, with the outcome of the process being mainly dependent on the carbophilic or oxophilic properties of the catalytic species ( Scheme 2 ).…”

Acidic Deep Eutectic Solvents as Active Media for Sustainable Synthesis of Biindoles Starting from 2,2’‐Diaminotolanes and Aldehydes

“…For many years we have been interested in the development of alternative strategies for the synthesis of heterocycles and organic scaffolds, with the aim to increase the degree of sustainability of the processes. We have tried to pursue this goal by exploiting domino [11] and multicomponent [12] approaches, coinage metal catalysis, [13] alternative energy sources, [14] and more eco‐friendly solvent and reagents [15] . In particular, in two recent works, we developed alternative approaches for the synthesis of 3,4‐fused 2‐pyranones [15a] and propargylamines [15b] based on the use of a more effective energy, source as microwaves, and the substitution of traditional solvents and catalysts with deep eutectic solvents (DESs) as “active” media able to promote the reaction under investigation [16] .…”