A FACILE PREPARATION OF 3-HALOFLAVONES USING HYPERVALENT IODINE^* CHEMISTRY

Abstract

Various 3-haloflavones were prepared by the reaction of the corresponding flavone derivatives with iodobenzene diacetate and trimethylsilyl halide under mild reaction conditions. The iodobenzene diacetate could be replaced by the polymersupported iodobenzene diacetate without the decreasing activity.The synthesis of a-haloenones from a,b-unsaturated carbonyl compounds provides an important functional group that facilitates palladium catalyzed carbon-carbon bond formation. 2 The application of this type of methodology to flavone has been rare despite the widespread synthetic utility of bisflavonoid intermediate. Therefore, new methods for the convenient 2101

The α-halogenation of α,β-unsaturated carbonyls and dihalogenation of alkenes using bisacetoxyiodobenzene/pyridine hydrohalides

“…10f,10g There is a single report on the use of BAIB in the presence of TMSCl to achieve a-chlorination; however, this example is limited to flavanone substrates. 11 The opportunity to develop operationally simple and broadly applicable conditions for the a-chlorination of enones, and our own synthetic needs, prompted an exploration of the utility of this reaction.…”

“…Furthermore, while there are various methods for the a-bromination 8 or a-iodination 9 of enones, there are far fewer procedures for a-chlorination. 10, 11 Most procedures for the a-chlorination of enones utilize strong oxidants such as Oxone Ò , 10a-c MCPBA, 10d or dimethyldioxirane 10e to generate electrophilic chlorinating agents; or potentially toxic and expensive selenium-based reagents. 10f,10g There is a single report on the use of BAIB in the presence of TMSCl to achieve a-chlorination; however, this example is limited to flavanone substrates.…”

Synthesis of Azaphilone-Based Chemical Libraries

“…Interestingly, we found that reaction of azaphilone 9{1} with acetic acid/acetic anhydride (1:1) in the presence of phenyliodine diacetate (PIDA) (μW 90 °C, 10 minutes) led to both acylation of the tertiary alcohol and acetoxylation 8 of the C5 position. However, O -acetylation could be avoided if the oxidation was performed at room temperature to afford exclusively tertiary alcohol 21 in 65% yield (Scheme 3).…”

Isoflavone Glycosides: Synthesis and Evaluation as α‐Glucosidase Inhibitors

“…Glycosylation of phenol 12 with imidate 3 under the promotion of BF 3 ·OEt 2 led to α-glycoside 13 in 62 % yield. Bromination of compound 13 was achieved with PhI(OAc) 2 and TMSBr at room temperature with pyridine as a base, [19] affording chromone 14 (67 %). Removal of the acyl protecting groups in 14 with K 2 CO 3 in a mixed solvent of MeOH/THF/H 2 O to compromise the solubility of the reactants provided desired 15 (77 %).…”