The pentacyclic alkaloid calothrixin B (1) has been synthesized in 5 steps from murrayaquinone A (9). The key step involved the union of boryl aniline 31 with brominated murrayaquinone A (26). In this transformation, alkylquinone 26 undergoes tautomerization to a quinone methide, which is intercepted by boryl aniline 31 to forge a new C-N bond. An intramolecular Suzuki coupling, followed by dehydrogenative aromatization, completed the synthesis of calothrixin B. Subsequent N-oxidation of calothrixin B delivered calothrixin A. The successful synthesis of these alkaloids and the challenges that led to the development of the final synthesis plan are reported herein.
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A rapid approach towards a specific carbazolelactam system related to calothrixin B.
Org Biomol Chem
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State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China.
Article Synopsis
- The text discusses a new, fast method for synthesizing specific compounds called pentacyclic carbazolelactams, which are connected to calothrixin B.
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State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, China; Natural Products Research Center of Guizhou Province, Guiyang 550014, China. Electronic address:
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School of Pharmaceutical Sciences, Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Chongqing University, Chongqing 401331, P. R. China.
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School of Food & Biological Engineering, Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, 230009, China. Electronic address:
Calothrixin A (CLA), as a carbazole-1,4-quinone alkaloid with unique indolo [3,2-j] phenanthridine framework, is a natural metabolite from the Calothrix cyanobacteria. Since the interaction to the functional serum albumins may play an important role in estimating its potential physiological or toxicological effects in vivo, we here explored the binding information of CLA with human serum albumin (HSA) by multi-spectroscopic experiments and computational approaches. The molecular docking results showed that there was one binding site of CLA to the site I (subdomain IIA) of HSA, causing the spontaneous formation of the ground state complex of CLA-HSA through the integration of hydrogen bond, hydrophobic interaction, and electrostatic interaction.
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State Key Laboratory for Functions and Applications of Medicinal Plants/Department of Immunology, Guizhou Medical University, Guiyang 550014, PR China; The Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academic of Sciences, Guiyang 550014, PR China. Electronic address:
Erythroleukemia is a malignant disease in the blood system. Quinones consists of a class of antitumor agents. Calothrixin B is a carbazole-1,4-quinone alkaloid isolated from Calothrix cyanobacteria with a unique indolo[3,2-j] phenanthridine framework.
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