Better protection

A new molecular catalyst shortens a widely used reaction into a one-step process, with a bonus: It makes the reaction’s products into one of two possible mirror-image forms.

When chemists synthesize compounds, they often add a protective group of atoms to a specific site on a molecule to prevent that site from reacting in subsequent steps. For example, a silicon-based group is added to an alcohol site in many syntheses of organic molecules, says Marc L. Snapper of Boston College.

However, protecting an alcohol site in this manner previously required up to seven chemical steps, he notes. To expedite the process, Snapper, Amir H. Hoveyda, and their Boston College coworkers searched for a small molecule that could catalyze that addition in a single step.

Furthermore, chemists often want to synthesize one of two possible mirror-image forms, or chiral molecules. The function of some molecules depends on its mirror-image form.

Snapper and his colleagues used their catalyst, which is chiral, on a compound with two alcohol groups in symmetrical positions on the molecule. The catalyst added the protecting group to only one position, making the compound also chiral. The researchers report in the Sept. 7 Nature that the reaction makes 98 percent of one mirror-image form and only 2 percent of the other.

The researchers are now working to improve the speed of the reaction and apply the catalyst to compounds with different numbers of alcohol groups.

Aimee Cunningham is the biomedical writer. She has a master’s degree in science journalism from New York University.

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