We previously reported the synthesis and the antimycobacterial activity of 4-(7,7-dimethyl-7H-furo[3,2-f]chromen-2-yl)pyridine. From this result, we sought to design simple synthetic accesses to related structures allowing the preparation of a diverse set of analogues. Two approaches were investigated. From 3-(2-bromo-7,7-dimethyl-8,9-dihydro-7H-furo[3,2-f]chromen-1-yl)propyl acetate, we prepared 2-arylated derivatives via Suzuki-Miyaura reactions between this bromine-bearing compound and various arylboronates. Moreover, and even more simple, we prepared the ((6-hydroxy-2,2,7,8-tetramethylchroman-5-yl)methyl)triphenylphosphonium salt via a selective bromination of 2,2,5,7,8-pentamethylchroman-6-ol. From this salt, a two stage Wittig reaction with an array of activated acids allowed the quick preparation of many analogues. The biological evaluation of the effect of these compounds on the growth of Mycobacterium bovis as well as Mycobacterium tuberculosis pointed out a fourfold improvement of the antimycobacterial properties for one of the compounds made. However, the many analogues which inhibited the growth of M. tuberculosis in the 0.6-5 microg/mL range turned out to be also cytotoxic on VERO cells growth at the same concentration range.
"In an effort to develop new anti-TB entities, Alvey et al. investigated a Wittig-type cyclization to prepare benzofurans (47). Using microwave irradiation, the reaction times could be shortened from 88 h to 1 h, compared with traditional reflux conditions. "
[Show abstract][Hide abstract] ABSTRACT: Abstract Tuberculosis (TB) represents a major public health problem. The growing number of (extensively) multi-drug resistance cases indicates that there is an urgent need for discovery of new anti-TB entities, addressed towards new and specific targets, and continuous development of fast and efficient synthetic strategies to access them easily. Microwave-assisted chemistry is well suited for small-scale laboratory synthetic work, allowing full control of reaction conditions, such as temperature, pressure, and time. Microwave-assisted high-speed organic synthesis is especially useful in the lead optimization phase of drug discovery. To illustrate the advantages of modern microwave heating technology, we herein describe applications and approaches that have been useful for the synthesis of new drug-like anti-TB compounds.
Upsala journal of medical sciences 03/2014; 119(2). DOI:10.3109/03009734.2014.899655 · 1.98 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: A novel synthetic method using an ionic liquid (IL) for a six-membered ring-closure cyclization is described. The ring-closure cyclization by nucleophilic C-alkylation was achieved with various halo- and alkanesulfonyloxyalkyl aromatic compounds in high yields with minimal byproducts using ILs as the reaction media in the absence of any catalyst. For example, the cyclization of 2-(3-methanesulfonyloxy-propoxy)naphthalene (1a) to 2,3-dihydro-1H-naphtho[2,1-b]pyran (2) in IL [bmim][PF6] proceeded selectively at 150°C for 24h in 85% yield.
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