Schwartz Hydrozirconation – an electrophilic addition reaction

In 1970, Helmut Weigold and Peter C. Wailes first prepared the reagent zirconocene hydrochloride. However, it was not until 1974 that Donald W. Hart and Jeffrey Schwartz demonstrated how this reagent could be used in organic synthesis. Hart and Schwartz reacted the organozirconium intermediates with electrophiles such as hydrochloric acid, bromine, and acid chlorides to generate the corresponding alkane, bromoalkanes, and ketones. Subsequently, the reaction of zirconocene hydrochloride ((C5H5)2ZrHCl), also known as Schwartz’s reagent, with multiple bonds to create alkenylzirconium compounds became known as the Schwartz hydrozirconation.

The reagent is commercially available, but can also be readily prepared by the reduction of zirconocene dichloride with lithium aluminum hydride. Schwartz's reagent is used in the synthesis of some macrolides, a class of natural products that show antibiotic and antifungal activity that has been exploited to produce several drugs. It was also used in the total synthesis of apoptolidin by Kyriacos Nicolaou to prepare an important vinyl iodide fragment of the molecule.

Mechanism of the Schwartz hydrozirconation reaction