N-Propargylic β-enaminocarbonyls: powerful and versatile building blocks in organic synthesis

Abstract

Nitrogen-containing heterocyclic compounds are not only prevalent in an extensive number of natural products and synthetic pharmaceuticals but are also used as building blocks in organic synthesis.

Synthesis of 3‐Keto Pyridines from the Conjugated Allenone – Alkynylamine Oxidative Cyclization Catalyzed by Supported Au Nanoparticles

“…Our latest report, regarding the smooth Au/TiO 2 ‐catalyzed cycloisomerization of conjugated allenones into furans, urged us to examine the possible Au‐catalyzed cyclization of N ‐propargylic β‐enaminones ( N ‐1,5‐enynes), compounds that could be formally obtained from an uncatalyzed reaction between allenones and propargylamine . Indeed, propargylamine adds quantitatively to the model allenone 1 in dioxane as solvent within 10 min at 25 °C, yielding exclusively the (Z)‐enaminone 1′ .…”

“…[10] However, it has been shown theoretically that a neutral Au(0) cluster can strongly interact to an alkyne, and the triple bond is activated toward nucleophilic attack, with the magnitude of π back-donation in the triple bond -Au interaction to be more significant than σ donation. [11] Our latest report, regarding the smooth Au/TiO 2catalyzed cycloisomerization of conjugated allenones into furans, [8c] urged us to examine the possible Aucatalyzed cyclization of N-propargylic β-enaminones (N-1,5-enynes), [12] compounds that could be formally obtained from an uncatalyzed reaction between allenones and propargylamine. [13] Indeed, propargylamine adds quantitatively to the model allenone 1 in dioxane as solvent within 10 min at 25°C, yielding exclusively the (Z)-enaminone 1'.…”

Methods for the direct synthesis of thioesters from aldehydes: a focus review

“…Since a number of advances and developments in the direct thioesterification of aldehydes have occurred from 1976 to present, a comprehensive review on this interesting research topic seems to be timely. In connection with our review articles on the formation of C-S bonds [11][12][13][14][15][16][17][18][19][20][21][22] and new methodologies in organic synthesis [23][24][25][26][27][28][29][30][31][32][33][34][35], in this Focus-Review, we will highlight recent progress on direct thioesterification of aldehydes with various thiol sources ( Figure 1), with special attention on the mechanistic aspects of the reactions. The cross-dehydrogenative coupling reactions of aldehydes with thiols are discussed first.…”

Alkaloid Synthesis via Gold‐Catalyzed Carbon‐Carbon Bond Formation Using Enamine‐type Nucleophile

“…On one hand, in modern asymmetric enamine catalysis, a variety of stereoselective carbon‐carbon bond‐forming reactions of carbonyl compounds could be implemented only by using catalytic amounts of chiral primary amine, or chiral secondary amine ,,. On the other hand, in transition metal catalysis, the reactivities of enamines can be tuned by flexible introduction of substituents either on the nitrogen atom,, or the double bond of enamine motif ,,…”