Four-Component Synthesis of 2-(N,N-Dialkylamino)-2,4,6-Cycloheptatrien-1-One Derivatives from Tropolone, an Isocyanide, a Primary Amine and an Aldehyde via Ugi-Smiles Coupling Reaction
Abstract:The use of Smiles rearrangement in Ugi-type couplings with tropolone allows very straightforward multicomponent formation of 2-(N,N-dialkylamino)-2,4,6-cycloheptatrien-1-one derivatives. The Ugi four-component reaction of isocyanides with tropolone (2-hydroxy-2,4,6-cycloheptatrien-1-one), primary amines and aldehydes proceeds smoothly and cleanly under mild conditions to afford 2-(N,N-dialkylamino)-2,4,6-cycloheptatrien-1-one derivatives in fairly good yields.
“…The use of Smiles rearrangements in Ugi‐type couplings has recently been extended to other acid enol derivatives such as squaric acid27a and tropolone27b (Scheme ).…”
Section: Scope and Mechanism Of Ugi–smiles Couplingsmentioning
“…The use of Smiles rearrangements in Ugi‐type couplings has recently been extended to other acid enol derivatives such as squaric acid27a and tropolone27b (Scheme ).…”
Section: Scope and Mechanism Of Ugi–smiles Couplingsmentioning
“…On the other hand, Ramazani et al successfully used tropolone ( 749 ) as the enol component in enol-Ugi reactions leading to 2-( N , N -dialkylamino)-2,4,6-cycloheptatrien-1-one derivatives ( 750 ; Scheme 157 ) [ 237 ]. Scheme 157 Ramazani’s enol-Ugi synthesis of tropolone-derived enamines …”
Stefano Marcaccini was one of the pioneers in the use of isocyanide-based multicomponent reactions in organic synthesis. Throughout his career at the University of Florence he explored many different faces of isocyanide chemistry, especially those geared towards the synthesis of biologically relevant heterocycles. His work inspired many researchers who contributed to other important developments in the field of multicomponent reactions and created a school of synthetic chemists that continues today. In this manuscript we intend to review the articles on isocyanide multicomponent reactions published by Dr. Marcaccini and analyse their influence on the following works by other researchers. With this, we hope to highlight the immense contribution of Stefano Marcaccini to the development of isocyanide chemistry and modern organic synthesis as well as the influence of his research on future generations. We believe that this review will not only be a well-deserved tribute to the figure of Stefano Marcaccini, but will also serve as a useful inspiration for chemists working in this field.
Graphical abstract
“…Due to their enormously large and highly reactive surface area, silica nanoparticles (SNPs) have the potential to exhibit superior catalytic activity in comparison to bulk counterparts [9,10].…”
ABSTRACT.A green and efficient method for the preparation of 2-(dibenzylamino)-2-aryl acetamide derivatives via a three-component reaction of an isocyanide, dibenzylamine and a phthalaldehyde derivative in the presence of silica nanoparticles (silica NPs, ca. 42 nm) as a catalyst under solvent free conditions at room temperature is described. The ease of work-up, green chemistry conditions and high yields of the products make this procedure a useful addition to modern synthetic methods. The silica nanoparticles that used in this reaction as a catalyst were prepared by thermal decomposition of rice hulls. Simple, green and cheap method for the preparation of the nanocatalyst represents a major advantage for this process. The structures of these compounds were confirmed by IR, 1 H and 13 C NMR spectroscopy.
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