Kostanecki-Robinson synthesis

Some improvement in the often moderate yields associated with the Kostanecki-Robinson synthesis has been achieved by substitution of a catalytic amount of triethylamine for the stoichiometric quantity of sodium carboxylate (44CB202). It is also possible to work at somewhat lower temperatures using this technique, an obvious advantage when sensitive groups are present. The modification is particularly attractive in the synthesis of complex hydroxyflavones (77T1405, 1411). A further development, the use of a tertiary amine as a solvent, has been advocated (78JOC2344). For instance, in the synthesis of 5,7-dihydroxy-3-methoxyflavone (galangin 3-methyl ether) (447) from w-methoxyphloracetophenone, the... 

This reaction has been widely used as Kostanecky-Robinson synthesis and should be discussed with regard to p 263/264. 

Kojic acid — see also Pyran-4-one, 5-hydroxy-2-hydroxymethyl-, 3, 611 acylation, 3, 697 application, 3, 880 occurrence, 3, 692 reactions, 3, 714, 715 with amines, 3, 700 with phenylhydrazine, 3, 700 synthesis, 3, 810 Kokusagine occurrence, 4, 989 Kokusaginine occurrence, 4, 989 synthesis, 4, 990 Koopmans theorem, 2, 135 Kostanecki-Robinson reaction chromone and coumarin formation in, 3, 819-821 mechanism, 3, 820 flavones, 3, 819... 

ROBINSON - ALLAN - KOSTANECKI Chromone Synthesis Synthesis of chromones or coumannes from o acyioxy aromatic ketones... 

Although the literature refers to the formation of chromones/coumarins as the Kostanecki reaction (and often the Kostanecki-Robinson reaction) and the synthesis of flavones as the Allan-Robinson reaction, others have chosen to merge the two reactions and refer to both transformations as the Kostanecki-Robinson reaction. This section will follow the latter school of thought, and use the Kostanecki-Robinson (K-R) nomenclature. 

The synthesis of chromones by the Kostanecki-Robinson method frequently yields a 3-acetylchromone. This acetyl group forms a 1,3-diketone with the pyran carbonyl group and is therefore labile in an alkaline medium. Treatment with aqueous carbonate or other base removes such groups but has no effect on other acyl substituents, for example the 6-acetyl of 3,6-diacetyl-2-methylnaphtho[l,2- ]pyran-4-one (516). 

Synthesis.—Application of the Kostanecki-Robinson reaction to 3-acyl-4-hydroxy-2//-pyran-2-one gave a mixture of pyrano[4,3-6]pyran-4,5-diones... 

This reaction is related to the Auwers Synthesis, Baker-Ollis Reaction, Kostanecki-Robinson Reaction dcnd Allan-Robinson Annulation. 

This reaction is closely related to the Baker-Venkataraman Rearrangement and Kostanecki-Robinson Reaction. Regarding the synthesis of flavone derivatives, the Allan-Robinson condensation is also related to the Algar-Flyn-Oyamada (AFO) Reaction and Auwers Synthesis. 

While the chromone moiety is found in several natural products, the Simonis chromone synthesis has not been exclusively used to prepare chromones. Other methods exist that are oftentimes more easily utilized, run under more mild conditions, or provide higher yields. For example, the Kostanecki-Robinson reaction has found application in this arena. However, alternative reaction types are not without their own issues therefore, the Simonis chromone synthesis remains a tool for the synthetic chemist. 

Mamedov VA, Kalinin AA, Gubaidullin AT, Litvinov lA, Levin YA (2003b) 3-Benzoylquinoxalin-2(lfl)-one in the Kostanecki-Robinson reaction. Synthesis and structure of 2-oxo-4-phenylpyrano[2,3-i)]quinoxaline. Chem Heterocyel Compd 39(1) 96-100. doi 10. 1023/A 1023028927007... 

Gripenberg in The Chemistry ofFlavonoid Compounds, Geissman, Ed. (New York, 1962) p 410. Mechanistic studies K. Bowden, M. Chehel-Amiran, J. Chem. Soc. Perkin Trans. II 1986, 2039. Synthetic applications P. K. Jain etal, Synthesis 1982, 221 J. Zhu etal., Chem. Commun. 1988,1549 A. V. Kalinin et al, Tetrahedron Letters 39,4995 (1998) D. C. G. Pinto et al, New J. Chem. 24, 85 (2000). Cf. Allan-Robinson Reaction Kostanecki Acylation. 

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