Reductive lithiation of cyclic benzofused ethers: a source of oxygen-functionalised organolithium compounds

Moderately lipophilic 2-(Het)aryl-6-dithioacetals, 2-phenyl-1,4-benzodioxane-6-dithioacetals and 2-phenylbenzofuran-5-dithioacetals: Synthesis and primary evaluation as potential antidiabetic AMPK-activators

Since the 1950's, AMP-kinase (AMPK) has been used as a promising target for the development of antidiabetic drugs against Type 2 diabetes mellitus (T2D). Indeed, the canonical antidiabetic drug metformin recruits, at least partially, AMPK activation for its therapeutic effect. Herein we present design and synthesis of 20 novel relatively polar cyclic and acyclic dithioacetals of 2-(Het)arylchroman-6-carbaldehydes, 2-phenyl-1,4-benzodioxane-6-carbaldehyde, and 2-phenylbenzofuran-5-carbaldehyde, which were developed as potential AMPK activators. Three of the synthesized dithioacetals demonstrated significant enhancement (≥70%) of glucose uptake in rat L6 myotubes. Noteworthy, one of the dithioacetals, namely 4-(6-(1,3-dithian-2-yl)chroman-2-yl)pyridine, exhibited high potency comparing to other molecules. It increased the rate of glucose uptake in rat L6 myotubes and augmented insulin secretion from rat INS-1E cells in pharmacological relevant concentrations (up to 2 μM). Both effects were mediated by activation of AMPK. In addition, the compound showed excellent pharmacokinetic profile in healthy mice, including maximal oral bioavailability. Such bifunctionality (increased glucose uptake and insulin secretion) can be used as a starting point for the development of a novel class of antidiabetic drugs with dual activity that is relevant for T2D treatment.

Intramolecular Carbolithiation of Allylo-Lithioaryl Ethers: A New Enantioselective Synthesis of Functionalized 2,3-Dihydrobenzofurans

A new and easy method for the diastereoselective synthesis of 3-functionalized 2,3-dihydrobenzofuran derivatives from allyl 2-bromoaryl ethers is described. The key step of this transformation involves an intramolecular carbolithiation reaction of allyl 2-lithioaryl ethers. The substituents in both the allyl and the aryl moieties play an important and decisive role in stopping the reaction at the benzofuran thus avoiding a gamma-elimination reaction. Finally, this process is amenable to the synthesis of enantiomerically enriched compounds by using (-)-sparteine as a chiral inductor.