Synthesis and Absolute Configuration of (‐)‐Chettaphanin I and (‐)‐Chettaphanin II.

Abstract

Terpenes Terpenes U 0200 Synthesis and Absolute Configuration of (-)-Chettaphanin I and (-)-ChettaphaninII. -(MARCOS*, I. S.; HERNANDEZ, F. A.; SEXMERO, M. J.; DIEZ, D.; BASABE, P.; PEDRERO, A. B.; GARCIA, N.; URONES, J. G.; Tetrahedron 59 (2003) 5, 685-694; Dep. Quim. Org.,

Synthesis of Bioactive Sesterterpenolides from ent-Halimic Acid. 15-Epi-ent-cladocoran A and B

“…The synthesis of compounds 1 and 2 was planned starting from ent -halimic acid methyl ester 3 , of known absolute configuration, due to its structural similarity to the targets. At present, ent -halimic acid is being employed in the synthesis of ent -halimanolides, and furan diterpenoids such as chettaphanin I and II …”

Crassifolins Q−W: Clerodane Diterpenoids From Croton crassifolius With Anti-Inflammatory and Anti-Angiogenesis Activities

“…The 1 H NMR spectrum of 7 ( Table 1 ) exhibited three olefinic protons [ δ H 8.05 (1H, s), 7.41 (1H, s), and 6.75 (1H, s)], one methine [ δ H 1.97 (m)], and three methyls [ δ H 1.20 (s), 1.08 (s) and 0.99 (d, J = 6.5 Hz)]. According to the 1D NMR spectroscopic data, the planar structure of compound 7 showed several similarities to methyl 5a,10a-epoxy-2,12-dioxo-13 (16),14-enthalimandien18-oate ( Marcos et al, 2003 ), and the main differences were the absence of a carbethoxy group, but the presence of a carboxylic acid group ( δ C 176.6, C-18). Thus, it indicated the carbethoxy group was replaced by a carboxylic acid group in 7 , which was supported by the HMBC cross peaks from H-3 ( δ H 2.70) to C-4 ( δ C 51.0) and from H 3 -19 ( δ H 1.08) to C-4/C-5/C-18 ( Figure 1 ).…”

Divergent Strategy in Marine Tetracyclic Meroterpenoids Synthesis

“…As shown in Scheme 7 b the synthesis of (−)-aureol ( ent - 1 ) used ent -halimic acid methyl ester 30 as the starting material. The degradation of the side chain of 30 was achieved [ 29 , 30 ] by oxidation with OsO 4 followed by Pb(OAc) 4 , which gave ketone 31 (94% yield, two steps). The synthesis of the endo -olefin 33 required the Wittig methylenation of 31 (87% yield) and subsequent acid isomerization of 32 (99% yield).…”