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Lewis Acid Catalyzed, Selective Cyclopropane-Ring Opening in Ingol Diterpene Derivatives

✍ Scribed by Masuna Srinivasulu; Vanimireddy Lakshmi Niranjan Reddy; Samala Malla Reddy; Veluri Ravikanth; Tuniki Venugopal Raju; Sistla Ramakrishna; Yenamandra Venkateswarlu

Publisher
John Wiley and Sons
Year
2005
Tongue
German
Weight
69 KB
Volume
88
Category
Article
ISSN
0018-019X

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✦ Synopsis

Abstract

Lewis acid mediated skeletal rearrangement of the ingol diterpenoids 1 and 4 via regio‐ and stereospecific cyclopropane‐ring opening afforded the four new compounds 2, 3, 5, and 6, named nivulianol A–D (Scheme 1). Their structures were established by means of IR, MS, and in‐depth NMR spectroscopic analyses. The rearranged congeners were tested for lipopolysaccharide (LPS)‐induced prostaglandin (PG) E~2~ (cyclooxygenase‐2) inhibition. Thereby, nivulianol B (=(1__S*,2__E,4__R*,5__S*,7__Z__,9__S*,11__R,13__S*,14__S*)‐14‐acetoxy‐5‐methoxy‐3,9,13‐trimethyl‐6‐(1‐methylethenyl)‐10‐oxo‐15‐oxatricyclo[9.3.1.0^1,11^]pentadeca‐2,7‐dien‐4‐yl (2__Z__)‐2‐methylbut‐2‐enoate; 3) was found to be significantly active, with an IC~50~ value of 36.3 μg/ml.

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