186032-77-9

Upstream product

• 132559-91-2 4-bromo-6-methyl-2H-pyran-2-one 
• 13984-49-1 (phenylethynyl)zinc chloride 
• 3757-88-8 tributylstannylethynylbenzene 
• 31913-41-4 6-methyl-4-tosyloxy-2(2H)-pyranone 
• 536-74-3 phenylacetylene 
• 17422-72-9 4-chloro-6-methyl-2H-pyran-2-one 
• 675-10-5 4-hydroxy-6-methyl-2-pyron 
• 488788-59-6 6-methyl-2-pyrone-4-trifluoromethanesulfonate 

Downstream Products

• 1097663-77-8 6-methyl-4-(1,2,2-triphenylvinyl)-2-pyrone 

Relevant academic research and scientific papers

Important consequences for gas chromatographic analysis of the Sonogashira cross-coupling reaction

On following the kinetics of the Sonogashira alkynylation reaction of halogenated 2-pyrone 1 with phenylacetylene we have found that turnover continues to occur in sample vials even after quenching by commonly employed silica adsorption methods and product elution with small quantities of CH 2Cl2. Trace quantities of Pd are carried through the silica plug. Addition of a CH2Cl2 solution of 1,2-bis(diphenylphosphino)ethane (dppe) to the quenched sample inhibits the reaction and represents a more reliable method for determining yields and reaction kinetics.

Palladium-Catalysed Alkynylations of 2-Pyrone (Pyran-2-one) Halides

The 2-pyrone sub-unit is found in a large number of natural products possessing broad-spectrum biological activity. As such, efficient synthetic methods are required to enable facile access to substituted 2-pyrone derivatives. Important conditions for the

Halogenated-2-pyrones in Sonogashira cross-coupling: limitations, optimisation and consequences for GC analysis of Pd-mediated reactions

The Sonogashira couplings of 4-bromo-6-methyl-2-pyrone (5) with phenylacetylene, mediated by Pd(PPh3)2Cl2 in the presence of a CuI co-catalyst, have been investigated in detail. The concentration of Pd dramatically influences the product yield, with lower Pd-loadings favouring higher conversions and purer cross-coupled product. A post reaction time-dependence in product conversion is seen in samples quenched solely on silica-gel (eluted with CH2Cl2). The effect is mirrored in reactions employing 4-nitro-bromobenzene (14) and to a lesser extent (E) and (Z)-ethyl 3-iodo-2-propenonate (16) under similar conditions. A more efficient quenching system (using excess dppe) has been developed to enable accurate determinations in product conversions. Alternatively, solvent and base (Et3N) removal in vacuo, or quench with saturated aqueous ammonium chloride, prevents further turnover in Sonogashira coupling. An ESI-MS study on samples eluted through silica was undertaken to probe the nature of the soluble Pd/Cu species. The Sonogashira cross-coupling of 4-chloro- and 6-chloro-2-pyrone (18 and 20, respectively) has further been investigated. The former undergoes successful coupling, however the latter decomposes in polar aprotic and protic solvents under standard conditions, through a chlorine substitution process, making Pd-mediated reactions problematic.

Sonogashira cross-coupling reactions catalysed by copper-free palladium zeolites

A heterogeneous copper-free [Pd(NH3)4]2+/ (NH4)Y catalyst was employed to achieve the heterogeneous Sonogashira reaction of aryl halides with terminal alkynes. Several reaction parameters like solvent, base and temperature were evaluated. When optimised, the coupling reaction of bromobenzene with phenylacetylene gave a 45% yield of diphenylacetylene within 3 h using only 1 mol % Pd. This catalyst was successfully applied to the coupling reaction of a range of aryl iodides and bromides: aryl iodides and activated aryl bromides gave almost quantitative yields and non-activated aryl bromides led to reasonable yields (20% to 45%). This heterogeneous [Pd(NH3)4]2+/(NH 4)Y catalyst was shown to be efficient, stable towards leaching and recyclable for the copper-free Sonogashira reaction.

An efficient synthesis of 4-alkenyl/alkynyl-6-methyl-2-pyrones via Pd-catalysed coupling on 4-bromo-6-methyl-2-pyrone

We herein report the efficient syntheses of biologically active 4-alkenyl- and 4-alkynyl-6-methyl-2-pyrones using Pd-catalysed coupling procedures. A palladium on carbon/triphenylphosphine combination is shown to be the most effective catalyst for Sonogas

Bioactive 4-substituted-6-methyl-2-pyrones with promising cytotoxicity against A2780 and K562 cell lines.

Bioactive synthetic 4-substituted-6-methyl-2-pyrones are reported. Various 4-substitutents have been incorporated using Pd-catalysed carbon-carbon bond coupling procedures. Preliminary screening of the 2-pyrones against human ovarian carcinoma (A2780) and