X-ray structure analysis of a solid solution of milbemycins A₃ and A₄

Abstract

Milbemycins A₃ and A₄ are pharmaceutically and agriculturally useful macrolides isolated from Streptomyces species. The molecular structures of the title compounds were unambiguously established by a single crystal X-ray analysis of the solid solution of both compounds. The crystals present trigonal system, space group P3₂ with Z = 3, unit cell dimensions: a = 12.2211(4), c = 17.5372(7) Å; V = 2268.4(1) Å³, μ = 0.082 mm^− 1; d = 1.183 g cm^− 3. An interesting system of intramolecular hydrogen bonds and weak intermolecular CH…O type hydrogen bond was observed in the solid state.

Keywords::

• milbemycin A₃
• milbemycin A₄
• X-ray structure
• solid solution

Acknowledgements

The authors thank ERDF project 2DP/2.1.1.1.0/10/APIA/VIAA/045 for materials. V.K. thanks ERDF project 2DP/2.1.1.2.0/10/APIA/VIAA/003 for an opportunity to present this work at 18th European Symposium on Organic Chemistry.