Concise synthesis of telmisartan via decarboxylative cross-coupling

Area of Science:

• Medicinal Chemistry
• Organic Synthesis
• Drug Discovery

Background:

• Telmisartan is a crucial angiotensin II receptor antagonist.
• Existing synthesis routes for telmisartan present challenges in efficiency and regioselectivity.
• Optimizing the synthesis of telmisartan is vital for its accessibility and therapeutic use.

Purpose of the Study:

• To develop a more efficient and regioselective synthesis of telmisartan.
• To introduce a novel key step involving decarboxylative cross-coupling.
• To improve the overall yield and streamline the synthetic pathway.

Main Methods:

• Decarboxylative cross-coupling of isopropyl phthalate with 2-(4-chlorophenyl)-1,3-dioxolane.
• Regioselective construction of the benzimidazole moiety via reductive amination-condensation.
• Convergent synthesis strategy.

Main Results:

• The key decarboxylative cross-coupling step achieved an 85% yield.
• A novel reductive amination-condensation sequence provided regioselective benzimidazole formation.
• The overall yield of telmisartan was 35% through an eight-step convergent synthesis.

Conclusions:

• The presented synthesis offers an efficient and regioselective route to telmisartan.
• The novel synthetic strategy significantly improves upon previously published methods.
• This optimized synthesis enhances the production of a key cardiovascular therapeutic agent.