Catalyst-free addition of ketone enolate to nonactivated multiple CÀCb onds involves non-complementary reaction partners and typically requires super-basic conditions. On the other hand, highly aggregated or solvated enolates are not reactive enough to undergo direct addition to alkenes or alkynes.Herein, we report an ew anionic cascade reaction for one-step assembly of intriguing molecular scaffolds possessing contiguous six-, five-, and four-membered rings,r epresenting af ormal [2+ +2] enol-allene cycloaddition. Reaction proceeds under very mild conditions and with excellent diastereoselectivity.D eeper mechanistic and computational studies revealed unusually slow proton transfer phenomenon in cyclic ketone intermediate and explained peculiar stereochemical outcome.

A synthetic method is presented for S−N bond formation starting from cheap and affordable materials. We show that (un)substituted N‐protected cyclic eight‐membered C2‐symmetric sulfenamides have been prepared in a few steps using this procedure. The synthetic utility of these ambipolar derivatives was demonstrated in a variety of synthetic transformations affording different S,N‐heterocyles of pharmaceutical relevance in one or two steps from simple starting materials.

Catalyst-free addition of ketone enolate to nonactivated multiple CÀCb onds involves non-complementary reaction partners and typically requires super-basic conditions. On the other hand, highly aggregated or solvated enolates are not reactive enough to undergo direct addition to alkenes or alkynes.Herein, we report an ew anionic cascade reaction for one-step assembly of intriguing molecular scaffolds possessing contiguous six-, five-, and four-membered rings,r epresenting af ormal [2+ +2] enol-allene cycloaddition. Reaction proceeds under very mild conditions and with excellent diastereoselectivity.D eeper mechanistic and computational studies revealed unusually slow proton transfer phenomenon in cyclic ketone intermediate and explained peculiar stereochemical outcome.

Hydroxymethyl furanoic acid and its derivatives have been synthesized in high yields and purity from gluconolactone.