A series of iodinated benzoboroxoles was designed and synthesized by using a successive metal–iodine exchange reaction of 3,4,5‐triiodoanisole. The reactivity and regioselectivity of the metal‐iodine exchange are remarkably controlled and provide the iodinated products in good yields. The synthesized iodobenzoboroxoles were screened for in vitro antimicrobial activity against two Gram‐positive strains of bacteria, Micrococcus luteus (ATCC 9341) and Bacillus cereus (ATCC 11778), and two Gram‐negative strains, Escherichia coli (ATCC 25922) and Serratia marcescens (ATCC 27117), by using a well‐diffusion assay and dilution methods. The in vitro antimicrobial evaluation indicated that 4‐iodo‐6‐methoxybenzo[c][1,2]oxaborol‐1(3H)‐ol (compound 24) possesses the most‐potent antibacterial activity against Gram‐positive strains with a minimum inhibitory concentration (MIC) of 0.016 and 0.013 mg/mL for Micrococcus luteus and Bacillus cereus, respectively. This report discloses a two‐step protocol for the synthesis of hitherto unknown 4‐iodobenzoboroxole and 7‐iodobenzoboroxole derivatives that is efficient, general in scope and scalable.
A facile and unprecedented synthesis of 2,3-diiodinated or 2,6-diiodinated diarylether/thioether derivatives through regioselective Ullmann-type cross couplings of 5-substituted-1,2,3-triiodobenzene and phenols/thiophenols is described. Remarkably, the coupling reactions are simply controlled by the type of nucleophiles and the nature of C5 substituent at 1,2,3-triiodoarenes providing the internal or terminal coupling products in high regioselectivity and good isolated yields. Noticeable steric and electronic effects were clearly observed on both 1,2,3-triiodoarene and nucleophile. The highest yields were isolated from a combination between either electron-poor 1,2,3-triiodoarenes and phenols or electron-rich 1,2,3-triiodoarenes and thiophenols. The optimized conditions were found to be suitable for several functional groups. Using this methodology, mammary carcinoma inhibitor BTO-956 is prepared in only one step with excellent regioselectivity and good isolated yield. This report discloses the first method to make 2,3-diiodinated and 2,6-diiodinated diarylethers/thioethers in one step that is efficient, regioselective, general in scope and truly remarkable precursors for other transformations.
Unique 2,6-diiodophenylboronic acid and 2,3-diiodophenylboronic acid derivatives have been synthesized via regioselective metal–iodine exchange (MIE) of 5-substituted 1,2,3-triiodoarenes. The regioselectivity of the reaction per se is remarkably controlled by the nature of the C5 substituent providing the desired diiodophenylboronic acids in moderate to good yields and with high site selectivity. The diiodophenylboronic acids were then examined for in vitro antimicrobial activity against four strains of bacteria Micrococcus luteus (ATCC 9341), Bacillus cereus (ATCC 11778), Escherichia coli (ATCC 25922), and Serratia marcescens (ATCC 27117) and one fungal strain Candida albicans using well diffusion assay and dilution method. It indicated that 5-fluoro-2,3-diiodophenylboronic acid possesses the most potent antibacterial and antifungal activity with MIC of 2.6 mg/mL for M. luteus and C. albicans. This report discloses a one-step protocol to access hitherto unknowns 2,6-diiodophenylboronic acid and 2,3-diiodophenylboronic acid derivatives that is scalable, good in scope, no chromatography is needed, and these compounds are difficult to prepare by other means.
A facile and unprecedented synthesis of 2,3-diiodinated Narylbenzimidamide derivatives through highly regioselective Buchwald-Hartwig coupling of 5-substituted-1,2,3-triiodobenzene and amidine is described. Remarkably, the amination reactions are proceeded exclusively at the terminal positions, the less sterically hindered, and the most regioactive positions. The highest yields were isolated from a combination between electron-poor 1,2,3-triiodoarenes and electron-poor benzimidamides. The optimized conditions were found to be suitable for many functional groups. This report discloses the first method to make 2,3-diiodinated N-arylbenzimidamides that is efficient, general in scope, highly regioselective, and truly remarkable precursors for other transformations [a]
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