Conjugated Ynones in Organic Synthesis

Abstract

This review article will consider the preparation and application of ynones in synthetic organic chemistry. Concerning the preparation of these bifunctional compounds, several methodologies starting from propargyl alcohols, acyl derivatives, both by using alkynylmetal reagents or by transition metal (mainly palladium and copper) catalyzed alkynylations, carbon monoxide (carbonylation of terminal alkynes and alkenes), and other substrates will be discussed. The reactivity and synthetic applications of ynones will be focused on conjugate additions with boron-, carbon-, nitrogen-, oxygen-, and other heteroatom-containing nucleophiles, as well as radicals. Then, cycloaddition processes will include [2 + 2] cycloadditions, [3 + 2] 1,3-dipolar cycloadditions (with azides, nitrones, azomethine imines and ylides, nitrile oxides, diazo compounds, and other dipoles), and [4 + 2] cycloadditions (mainly Diels–Alder-type reactions). The reduction of the triple bond, addition to the carbonyl group (using carbon- and heteronucleophiles and reductions), and other not so commonly used processes (such as aldol reactions, cyclizations, and isomerizations) will be considered at the end.

Gold‐catalyzed Cyclization of Non‐conjugated Ynone‐oxime Derivatives: Incorporation of Solvent Molecule

“…[7] Conjugated or non-conjugated ynone skeletons are robust starting molecules to reveal different heterocyclic rings (Scheme 1, B). [8] However, non-conjugated ynone molecules were focused less than the conjugated ynones. [9] The ynoneoxime molecules, we worked on in this study, were recently converted into pyridine and isoxazoline rings under different reaction conditions (Scheme 1, C).…”

Formyl MIDA Boronate: C1 Building Block Enables Straightforward Access to α‐Functionalized Organoboron Derivatives

“…Due to wide application of ynones and 1,3‐dicarbonyl compounds in synthetic organic chemistry, we next aimed at the chemoselective oxidation of α‐hydroxy boronates, which allowed synthesis of boron‐substituted analogues of ynones and β‐dicarbonyl compounds for the first time (Scheme ). Dess–Martin oxidation was adapted for the preparation of 33 – 36 by using the CHCl 3 ‐CH 3 CN (9:1) as the solvent to ensure good solubility of the starting alcohols (conditions A ).…”

Formyl MIDA Boronate: C1 Building Block Enables Straightforward Access to α‐Functionalized Organoboron Derivatives

“…Due to wide application of ynones [43,44] and 1,3-dicarbonyl compounds [45][46][47] in synthetic organic chemistry,wenext aimed at the chemoselective oxidation of a-hydroxy boronates, which allowed synthesis of boron-substituted analogues of ynones and b-dicarbonyl compounds for the first time (Scheme 8). Dess-Martin oxidation was adapted for the preparation of 33-36 by using the CHCl 3 -CH 3 CN (9:1) as the solvent to ensure good solubility of the starting alcohols (conditions A).…”