Question

Labetalol, a β-blocker antagonist of epinephrine and norepinephrine is commonly used in treating high blood pressure. Labetalol can be synthesized from a primary amine and an epoxide. Using the starting materials below, add curved arrows to complete the mechanism for the synthesis of Labetalol. The general base (:B) will be used for proton transfers.

Answer 1

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Answer 2

The first step is attack of proton on the epoxide.

Then attack of primary amine (nucleophile) followed by removal of proton by base.

The detailed mechanism is