Pyripyropene Derivative Synthesis via Selective Protection
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Solution Overview
Problem
The existing processes for producing pyripyropene derivatives with acyloxy groups at the 1- and 11-positions and a hydroxyl group at the 7-position suffer from low yield and unsuitability for quantity synthesis, as disclosed in WO 2006/129714 and Japanese Patent Application Laid-Open No. 259569/1996, which do not provide a specific method for utilizing protective groups effectively in this production.
Innovation Solution
A process involving the acylation of hydroxyl groups at the 1- and 11-positions of compound Fb, followed by deacylation and protection of hydroxyl groups using appropriate protective groups, allowing for the high-yield production of pyripyropene derivatives with acyloxy groups at the 1- and 11-positions and a hydroxyl group at the 7-position, utilizing pyripyropene A as a naturally occurring starting substance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If nonselective hydrolysis of acyloxy is used to produce pyripyropene derivatives, then the process can be simplified, but the yield becomes low and the process becomes unsuitable for quantity synthesis
Solution Approach 1:
The patent applies preliminary protection of the 7-position hydroxyl group before acylation reactions. By protecting the hydroxyl group at the 7-position with appropriate protecting groups (such as silyl ethers, esters, or ethers) before performing acylation at the 1- and 11-positions, the method prevents unwanted side reactions and enables selective modification. This preliminary protective action allows subsequent deprotection to yield the desired product with high yield and purity, making the process suitable for quantity synthesis while maintaining reasonable complexity.
2Productivity
If protective groups are used in the synthesis of pyripyropene derivatives, then selectivity and yield can be improved, but the process complexity increases
Solution Approach 1:
The patent applies local quality by using different protecting groups for different positions (1-, 7-, and 11-positions) of the pyripyropene molecule. The 7-position hydroxyl group is protected with specific protecting groups (such as silyl ethers, esters, or ethers) that can be selectively introduced and removed. This localized protection strategy allows selective acylation at the 1- and 11-positions while maintaining the 7-position hydroxyl group intact for the final product, thereby improving yield and selectivity with controlled complexity.
3Manufacturing precision
If multiple protective group operations are performed, then the purity and selectivity of the product improve, but the manufacturing time and cost increase
Solution Approach 1:
The patent performs preliminary protection of the 7-position hydroxyl group before acylation reactions. This preliminary protective action prevents side reactions during acylation at the 1- and 11-positions, ensuring high product purity. The protecting group is introduced in advance, allowing subsequent reactions to proceed with high selectivity. After acylation, a single deprotection step yields the final product with the desired purity, thereby minimizing total manufacturing time while achieving high precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process enables the production of pyripyropene derivatives at high yield, making them suitable for use as effective pest control agents and providing intermediates for further synthesis, thereby overcoming the limitations of previous methods.
Implementation Method 1
acylating hydroxyl at the 1- and 11-positions of compound Fb with an acylating agent corresponding to R' to give compound B2b
Implementation Method 2
removing the protective group at the 7-position of compound B2b
Data Source
AI summary
Claimed is a process for producing a compound of formula C: wherein R' represents a (cyclic C3-6 alkyl)carbonyl, and wherein R1b is used as a protective group for hydroxyl at the 7-position of compound C. R1b represents formyl; optionally substituted straight chain C1-4 alkylcarbonyl; optionally substituted benzyl; group -SiR3R4R5 optionally substituted by halogen atom wherein R3, R4 and R5 each independently represent straight chain or branched chain C1-6 alkyl or phenyl; C1-6 alkyloxy-C1-6 alkyl optionally substituted by halogen atom; C1-6 alkylthio-C1-6 alkyl optionally substituted by halogen atom; straight chain, branched chain or cyclic C1-4 alkyl optionally substituted by halogen atom, provided that when alkyl in the C1-4 alkyl group is of a branched chain or cyclic type, the alkyl group is C3-4 alkyl; C2-6 alkenyl optionally substituted by halogen atom; C2-6 alkynyl optionally substituted by halogen atom; or an optionally substituted saturated or unsaturated five- or six-membered heterocyclic group. The process can produce pyripyropene derivatives that have acyloxy groups at the 1- and 11-positions and a hydroxyl group at the 7-position and are useful as insect pest control agents at a high yield.