Synthesis and absolute configuration of (−)-chettaphanin I and (−)-chettaphanin II

A New Halimane Diterpenoid from Croton crassifolius

“…These spectral data suggested the presence of a halimane diterpenoid skeleton with a β-substituted furan ring in 1. The 13 C-NMR spectrum was similar to chettaphanin I (2), 9,16 except for the lack of a C-12 keto carbonyl group, instead of the presence of olefinic carbons at 142.3 (C-11), and 130.2 (C-12). The HMBC spectrum also showed correlations between H-11 and C-1, C-8, C-9, C-10, suggested that the presence of a cyclopentadiene ring formed by C-9, C-10, C-1, C-12 and C-11 in 1.…”

“…As part of our continuing studies on the constituents of the traditional herbal medicines, 14,15 the present paper deals with the isolation and structural elucidation of a new halimane diterpenoid, named crassifoliusin A (1), along with a known halimane diterpenoid, chettaphanin I (2), 9,16 from the 95% aqueous EtOH extract of the roots of C. crassifolius. The cytotoxicity of compound 1 was evaluated against HepG2, SGC-7901, and K562 cell lines.…”

“…By comparing its NMR spectroscopic data with those in the literature, its structure was determined to be chettaphanin I (2) 9,16 ( Fig. 1).…”

Synthesis of an ent-Halimanolide from ent-Halimic Acid

“…Our group has transformed ent -halimic acid 1 , a diterpene of known structure and absolute configuration, into chettaphanin I and II, which confirmed their structure and absolute configuration [4,6]. In this paper, we report the synthesis of ent -halimanolide 2 , in order to confirm the structure of the natural compound and do SAR studies.…”

“…(Euphorbiaceae), known in Thailand as “Chettaphangki,” is the only member of the genus Cladogynos and the roots are used as a carminative in Thai folk medicine. Chettaphanin I [4,5] and II [6,7], are the main components from their roots of this plant and the first to be known. Recently, in addition to chettaphanin I and II, isolation from the root extract of a series of furan diterpenes 2 - 4 with ent -halimane skeletons has been described [8].…”