A novel type of hypervalent iodine(III) reagents, vinylbenziodoxolones (VBX), has been synthesized in a one-pot reaction from 2-iodobenzoic acid. VBX is bench stable, has been thoroughly characterized and the cyclic structure is supported by X-ray analysis. The reactivity of VBX was investigated in vinylation of nitrocyclohexane, and delivered vinylated products with opposite regioselectivity compared to acyclic vinyl(aryl)iodonium salts. The reagents could become a powerful tool in vinylation reactions under both metal-free and metal-catalyzed conditions.

[reaction: see text] The three-component condensation between an amine, an aldehyde, and an alpha-acidic isocyanide efficiently provides substituted 2-imidazolines in a one-pot reaction under mild conditions.

A novel multicomponent synthesis of 5-alkoxyoxazoles, based on a new reactivity profile of α-isocyanoacetates, is described. Thus, simply heating a solution of amine, aldehyde, and α-(EWG-phenyl)-α-isocyanoacetate or α-(4-pyridyl)-α-isocyanoacetate (EWG=electron-withdrawing group) in toluene provided 5-alkoxyoxazoles in good to excellent yields. Reaction of the 5-alkoxyoxazoles with various α,β-unsaturated acyl chlorides led to the formation of epoxytetrahydropyrrolo[3,4-b]pyridin-5-ones by a domino N-acylation/Diels-Alder cycloaddition sequence. Subsequent fragmentation under basic conditions provided 6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-ones. A four-component synthesis of the pyridin-5-one compounds, without isolation of the 5-alkoxyoxazole, was subsequently developed.

I: hyperfond of a triple bond! The first one-pot synthesis of alkynyl(aryl)iodonium salts directly from aryl iodides has been developed. The reaction is fast and high yielding, and can be extended to the synthesis of alkynyl benziodoxolones (see scheme). The developed methodology is expected to greatly facilitate the access to this interesting class of hypervalent iodine reagents, and many new application areas are foreseen.

Enantioselective multicomponent reaction: in the presence of a catalytic amount of chiral BINOL-derived phosphoric acid (TRIP), the reaction of an α-isocyanoacetate 1, an aldehyde 2, and an aniline 3, followed by addition of a toluene solution of α,β-unsaturated acyl chloride 4 afforded the oxa-bridged tricycle 5 in excellent yield, diastereoselectivity, and enantioselectivity. Six chemical bonds, five stereogenic centers, and three cycles were formed in this one-pot four-component reaction.