Wagner-Meerwein Rearrangement: Mechanism, Applications, and Role in Organic Synthesis M.Pharmacy 1st Semester 2022 (2021-2022) Previous Year's Question Papers/Notes Download - HK Technical PGIMS

The Wagner-Meerwein rearrangement, a fundamental carbocation 1,2-shift reaction pivotal in organic synthesis. This guide covers:

• Mechanism: Acid-catalyzed conversion of alcohols/alkyl halides to olefins via carbocation intermediates.

• Key Features: Stereospecific [1,2]-shifts (alkyl, hydride, aryl), ring expansions/contractions, and thermodynamic stabilization.

• Applications:

  • Synthesis of terpenes (e.g., α-pinene → bornyl chloride → camphene).

  • Petroleum cracking and hydrocarbon isomerization.

  • Steroid/epoxide rearrangements and triterpene transformations.

  • Pharmaceutical intermediates (e.g., neopentyl derivatives).

• Catalysts: Lewis acids (BF₃, AlCl₃) and protic acids (H₂SO₄).