Stereospecific consecutive epoxide ring expansion with dimethylsulfoxonium methylide.

Consecutive ring-expansion reactions of oxiranes with dimethylsulfxonium methylide were studied experimentally and modeled computationally at the density functional theory (DFT) and second-order Møller-Plesset (MP2) levels of theory utilizing a polarizable continuum model (PCM) to account for solvent effects. While the epoxide to oxetane ring expansion requires 13-17 kcal mol(-1) activation and occurs at elevated temperatures, the barriers for the ring expansions to oxolanes are higher (ca. 25 kcal mol(-1)) and require heating to 125 °C.

Isolation of the key intermediates in the catalyst-free conversion of oxiranes to thiiranes in water at ambient temperature.

Herein we shed light on the mechanism of the reaction of epoxides with ammonium thiocyanate to give the corresponding thiiranes in water, and we present a computational mechanistic model for this highly useful reaction.

Cooperative Brønsted acid-type organocatalysis: alcoholysis of styrene oxides.

We present a mild and efficient method for the completely regioselective alcoholysis of styrene oxides utilizing a cooperative Brønsted acid-type organocatalytic system comprised of mandelic acid (1 mol %) and N,N'-bis-[3,5-bis-(trifluoromethyl)phenyl]-thiourea (1 mol %). Various styrene oxides are readily transformed into their corresponding beta-alkoxy alcohols in good to excellent yields at full conversion. Simple aliphatic and sterically demanding, as well as unsaturated and acid-sensitive alcohols can be employed.

Hydrophobic amplification of noncovalent organocatalysis.

The effects of hydrogen-bonding organocatalysts and water for the acceleration of epoxide openings with a variety of nucleophiles are additive and lead to excellent yields of the catalyzed reactions in water.