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A six-step route starting from a readily available vinyl boronate was identified to produce an enantioenriched cyclopropanol in an overall 16% yield. Key steps involve the use of lithium acetylide-ethylene diamine complex 5 and an enzymatic resolution of a racemic cyclopropanol acetate. Process safety considerations surrounding the use of 5 were examined, and an improved procedure is described which was safely demonstrated at multikilogram scale.

In this Letter, we describe a practical, green iodination of pyrazoles to form the corresponding 4-iodopyrazole derivatives. The reaction takes place in water, using only 0.5 equiv of iodine and 0.6 equiv of hydrogen peroxide, a system that generates water as the only reaction by-product.

The ruthenium(0) catalyst generated from Ru3(CO)12 and tricyclohexylphosphine or BIPHEP promotes successive C–C coupling of dienes to vicinally dioxygenated hydrocarbons across the diol, hydroxyketone, and dione oxidation levels to form products of [4 + 2] cycloaddition. A mechanism involving diene-carbonyl oxidative coupling followed by intramolecular carbonyl addition from the resulting allylruthenium intermediate is postulated.

The ruthenium(0) catalyst generated from Ru3(CO)12 and tricyclohexylphosphine or BIPHEP promotes successive C–C coupling of dienes to vicinally dioxygenated hydrocarbons across the diol, hydroxyketone, and dione oxidation levels to form products of [4 + 2] cycloaddition. A mechanism involving diene-carbonyl oxidative coupling followed by intramolecular carbonyl addition from the resulting allylruthenium intermediate is postulated.

In this Letter, we describe a practical, green iodination of pyrazoles to form the corresponding 4-iodopyrazole derivatives. The reaction takes place in water, using only 0.5 equiv of iodine and 0.6 equiv of hydrogen peroxide, a system that generates water as the only reaction by-product.