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Lewis Acid Catalyzed, Selective Cyclopropane‐Ring Opening in Ingol Diterpene Derivatives
Author(s) -
Srinivasulu Masuna,
Reddy Vanimireddy Lakshmi Niranjan,
Reddy Samala Malla,
Ravikanth Veluri,
Raju Tuniki Venugopal,
Ramakrishna Sistla,
Venkateswarlu Yenamandra
Publication year - 2005
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200590189
Subject(s) - chemistry , cyclopropane , diterpene , lewis acids and bases , stereochemistry , stereospecificity , ring (chemistry) , prostaglandin , ketone , catalysis , organic chemistry , biochemistry
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.