Redetermination and absolute configuration of atalaphylline.

Area of Science:

• Crystallography
• Organic Chemistry
• Natural Products Chemistry

Background:

• Acridone alkaloids are a class of natural products with potential biological activities.
• Previous crystallographic studies reported the acridone alkaloid 1,3,5-trihydr-oxy-2,4-bis-(3-methyl-but-2-en-yl)acridin-9(10H)-one crystallizing in space group P2(1)2(1)2(1).
• However, the absolute configuration could not be determined using molybdenum radiation.

Purpose of the Study:

• To determine the absolute configuration of the acridone alkaloid.
• To refine crystallographic data using a different radiation source.
• To confirm structural and packing features of the molecule.

Main Methods:

• Single-crystal X-ray diffraction analysis.
• Refinement of the Flack parameter.
• Data collection using copper (Cu) radiation.

Main Results:

• The absolute configuration of the acridone alkaloid was successfully determined.
• The crystal structure and molecular packing were found to be consistent with previous reports.
• The use of Cu radiation enabled the determination of absolute stereochemistry.

Conclusions:

• The absolute configuration of the acridone alkaloid 1,3,5-trihydr-oxy-2,4-bis-(3-methyl-but-2-en-yl)acridin-9(10H)-one has been unequivocally established.
• This study highlights the utility of Cu radiation in resolving absolute configurations when Mo radiation is insufficient.
• The findings contribute to the structural understanding of acridone alkaloids.