Uses of o-Hydroxybenzoylacetone in the Synthesis of Some Substituted 2-Methylchromones, Chelating Agents, and Related Materials

Abstract

The nitration of o-hydroxybenzoylacetone (1) gave either the unexpected 2,3-benzofurandione 2-oxime or 2-methyl-3-nitrochromone depending on the conditions of the reaction. Nitrosation of 1 gave 1-(o-hydroxybenzoyl)propane-1,2-dione 1-oxime which reacts with hydroxylamine to give 1-(o-hydroxybenzoyl)propane-1,2-dione 1,2-dioxime. Both of the oximes exhibit strong chelating properties. Bromination of 1 gave 3-bromo-2-dibromomethylchromone or 3-bromo-2-methylchromone. The condensation of diethyl malonate with 3-bromo-2-methylchromone was studied as well.

Comments on “Uses of o-Hydroxybenzoylacetone in the Synthesis of Some Substituted 2-Methylchromones, Chelating Agents, and Related Materials”

“…The details are also included in Scheme . It may also be pointed out that chromones exhibit a characteristic absorption for 5-H in their 1 H NMR spectra, downfield from all other aromatic protons, which is absent in the 1 H NMR spectrum reported in the present paper . Simple 3-nitrochromone ( VIII ) was also prepared from IV by reaction with triethyl orthoformate in the presence of pyridine…”

“…It may also be pointed out that chromones exhibit a characteristic absorption for 5-H in their 1 H NMR spectra, 8 downfield from all other aromatic protons, which is absent in the 1 H NMR spectrum reported in the present paper. 1 Simple 3-nitrochromone (VIII) was also prepared from IV by reaction with triethyl orthoformate in the presence of pyridine. 7 The reactivity of the methyl group in II obtained by us was demonstrated through styrylation with aromatic aldehydes to yield corresponding 2-styryl-3-nitrochromones (VII), which on subsequent cyclization gave condensed pyrroles, 9 conclusively proving the structure of II.…”

Synthesis and reactions of halogen-containing chromones

“…Indeed, when chloroform was replaced by ethanol, the yield of chromone 19b increased to 90%, while the reaction performed in acetic acid in the presence of excess bromine led to 3-bromo-2-dibromomethylchromone. 45 In the reaction of 2-methylchromone (1e) with bromine in AcOH, chromone 19b is formed in a low yield (25%). 2 Upon an attempt to prepare compound 19b from 2-methylchromone (1e) and N-bromosuccinimide in CCl 4 , as described in an earlier publication, 46 three products were isolated, namely, chromone 19b, 2-(bromomethyl)chromone and 3,6,8-tribromo-2-methylchromone.…”

“…118 3-Bromo-2-methylchromone (19b) reacts with diethyl malonate in the presence of Et 3 N in acetone being converted into diethyl (2-methylchromon-3-yl)malonate. 45 However, the reaction pathway between 3-bromochromone (9) and ethyl N-(diphenylmethylidene)glycine changes (apparently, for steric reasons). In this case, elimination of hydrogen bromide from the Notably, as in the reactions with amines, 6-bromonorkhellin 62 shows a specific behaviour in reactions with C-nucleophiles; in particular, it reacts with ethyl acetoacetate and ethyl and tertbutyl cyanoacetates in the same way as 3-bromochromone (9), i.e., to give furan 92 and 6-substituted norkhellins 93, whereas the reaction with diethyl malonate produces furocoumarone derivative 94.…”

New Synthesis of 2,3‐Diarylxanthones.

“…Bromination and cyclisation of this 1,3-diketone 3 into the desired 3-bromo-2-methylchromone (4) was achieved in an one-pot synthesis, using 1.5 mol of bromine in ethanol followed by acidification. 8 Scheme 1 Reagents and conditions: (i) CH 3 COCl, pyridine, r.t., 15 h; (ii) NaH or t-BuOK, THF, reflux, 2 h; (iii) 1. CH 3 COCl, t-BuOK, THF, r.t., 2 h; 2. t-BuOK, reflux, 2 h; (iv) 1.…”