The Sumatran forest plants Lerchea cf. bracteata and L. parviflora were found to contain alkaloids and their extract showed siginificant activity toward some testing pathogenic microbes. Isolation work on L.cf bracteata yielded known quaternary alkaloid N(b)-methylantirhine (2) while L. parviflora gave 5,6-dihydroflavopereirine (3).
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Chemistry
January 2025
Indian Institute of Technology Kharagpur, Chemistry, Paschim Midnapore, 721302, Kharagpur, INDIA.
All-carbon quaternary and tertiary stereocenters connected at the C2-position of functionalizable C3-alkylated indole nucleus are commonly occurring frameworks found in many indole alkaloids of medicinal importance. Their direct access is scarcely reported, a long-standing problem, and developing a unique yet simple method can pave the pathway to an entirely different retrosynthetic route for the total synthesis of these alkaloids. Herein, this problem is addressed by developing an unprecedented branch-selective allylation strategy employing a broad range of structurally and electronically different 3-alkenyl-indoles and allylboronic acids.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Department of Chemistry, College of Sciences, Tianjin University of Science and Technology, Tianjin 300457, People's Republic of China.
A sequential [3 + 2]/[2 + 1] annulation reactions of benzimidazole- and indole-derived acrylonitriles with vinylsulfonium salts have been developed for the first time, and shown to provide in yields of 32 to 98% a series of azabicyclo[3.1.0]hexanes containing each a cyano-substituted tetrasubstituted carbon stereocenter with >20 : 1 dr.
View Article and Find Full Text PDFJ Org Chem
December 2024
Beijing National Laboratory of Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China.
The construction of C-C bonds to form all-carbon quaternary centers remains a significant challenge in synthetic chemistry. Herein, we report a tandem process involving a 1,2-migration of a tetra-coordinated boron intermediate followed by a Claisen rearrangement of the boron enolate, achieved through a reaction between allyl diazoacetates and trialkylboranes. The transformation forms two C-C bonds at the carbenic position of diazo substrate in a single-step operation under neutral conditions.
View Article and Find Full Text PDFEur J Med Chem
February 2025
Department of Life Sciences, Changzhi University, Changzhi, 046011, Shanxi, China; Department of Chemistry, Changzhi University, Changzhi, 046011, Shanxi, China. Electronic address:
A novel series of steroidal β-carboline quaternary ammonium derivatives (SCQADs) derived from natural cholic acid and its derivatives was designed, synthesized and biologically evaluated against four Gram-positive bacteria for the first time. Most of these derivatives exhibited promising antibacterial activity against the tested strains, particularly, compound 21g displayed strong antibacterial activity against MRSA (MIC = 0.5-1 μg/mL) with low cytotoxicity.
View Article and Find Full Text PDFChem Asian J
December 2024
IISER Bhopal: Indian Institute of Science Education and Research Bhopal, Chemistry, 462066, Bhopal, INDIA.
Natural product synthesis has been the prime focus for the development of new chemical transformations and the drug discovery. The dimeric and oligomeric hexahydropyrrolo[2,3-b]indole alkaloids represent a architecturally intriguing class of cyclotryptamine alkaloids. These alkaloids share contiguous stereogenic centers with vicinal all-carbon quaternary stereogenic centers.
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