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A total synthesis of (-)-Hortonone C
Doleshwar Niroula1, Liam P Hallada2, Snezna Rogelj3
1Department of Chemistry, New Mexico Institute of Mining and Technology, Socorro NM 87801, United States.
Tetrahedron
|January 10, 2017
Summary
Total synthesis of cytotoxic terpenoid hortonone C achieved, confirming its absolute stereochemistry. Key intermediate (+)-4 was synthesized via asymmetric conjugate addition or Hajos-Parrish ketone elaboration, enabling stereocontrolled ring expansion.
Area of Science:
- Organic Chemistry
- Natural Product Synthesis
- Stereochemistry
Background:
- Terpenoids are a diverse class of natural products with significant biological activities.
- Hortonone C is a cytotoxic terpenoid that presents a challenging synthetic target.
- Understanding the stereochemical configuration of natural products is crucial for structure-activity relationship studies.
Purpose of the Study:
- To achieve the total synthesis of the cytotoxic terpenoid hortonone C.
- To confirm the absolute stereochemistry of hortonone C through synthesis.
- To develop efficient synthetic routes for complex terpenoids.
Main Methods:
- Asymmetric conjugate addition strategy for intermediate synthesis.
- Elaboration of the Hajos-Parrish ketone.
- Dissolving-metal reduction and enolate trapping for stereochemical control.
- Silyl enol ether formation for ring expansion.
Main Results:
- Successful total synthesis of hortonone C.
- Confirmation of the cis-stereochemistry at the ring fusion.
- Determination of the absolute configuration as (6S,7S,10S) by comparing optical rotation data with the natural product.
- Efficient synthesis of key intermediate (+)-4 using two distinct approaches.
Conclusions:
- The total synthesis of hortonone C was successfully accomplished.
- The absolute stereochemistry of natural hortonone C was unequivocally confirmed as (6S,7S,10S).
- The synthetic strategies employed provide valuable insights into the construction of complex terpenoid frameworks.