Triterpenoids from Abies species

Forrestiacids A and B, Pentaterpene Inhibitors of ACL and Lipogenesis: Extending the Limits of Computational NMR Methods in the Structure Assignment of Complex Natural Products

“…More details came from the interpretation of its 2D NMR data. The presence of two discontinuous spin systems of CH 2 (15)‐CH 2 (16) and CH 3 (21)‐CH(20)‐CH 2 (22) as evidenced from the 1 H‐ 1 H COSY correlations, and the HMBC correlations from H 3 ‐18 to the spiro‐carbon (C‐13) and C‐16/C‐17/C‐20, from H 2 ‐30 to C‐13/C‐14/C‐15, and from H 3 ‐19 to C‐9, confirmed the assignment of an 8(14→13)‐ abeo ‐17,13‐friedo‐lanost‐8,14(30)‐diene [13] fragment for 1 (Figure 3 a). Consistent with this, the observed quaternary carbon signal at δ C 67.9 was typical for a double allyl nodal carbon atom (C‐13) in this class of rearranged 6/6/5/5‐fused lanostanes [13] .…”

“…The presence of two discontinuous spin systems of CH 2 (15)‐CH 2 (16) and CH 3 (21)‐CH(20)‐CH 2 (22) as evidenced from the 1 H‐ 1 H COSY correlations, and the HMBC correlations from H 3 ‐18 to the spiro‐carbon (C‐13) and C‐16/C‐17/C‐20, from H 2 ‐30 to C‐13/C‐14/C‐15, and from H 3 ‐19 to C‐9, confirmed the assignment of an 8(14→13)‐ abeo ‐17,13‐friedo‐lanost‐8,14(30)‐diene [13] fragment for 1 (Figure 3 a). Consistent with this, the observed quaternary carbon signal at δ C 67.9 was typical for a double allyl nodal carbon atom (C‐13) in this class of rearranged 6/6/5/5‐fused lanostanes [13] . The carbonyl at δ C 216.7 was assigned to C‐3 based on its HMBC correlations with the geminal methyls H 3 ‐28 and H 3 ‐29 as a keto group, whereas the correlations from H 2 ‐22 and H‐24 to a carbonyl at δ C 213.8 allowed it to be positioned at C‐23 as an additional keto group.…”

Use of Circular Dichroism to Determine the Absolute Configuration of a Pimarane Diterpenoid from the Southern African Sclerocroton integerrimus (Euphorbiaceae)

“…17-Hydroxy-ent-pimara-8(14),15-dien-3-one was previously reported from the roots of Suregada glomerulata (Blume) Baill. (Euphorbiaceae) and its specific rotation reported to be -18.9[9].…”

“…17-Hydroxy-ent-pimara-8( 14),15-dien-3-one (1) was isolated as an amorphous solid. HRESIMS indicated a molecular formula of (Euphorbiaceae) and its specific rotation reported to be -18.9 [9].…”

Triterpenoids fromAbies species

“…The capacity coefficients k" were 1.99 (5), 3.58 (1), 238 (7), 4.29 (6), and 4.74 (9). The IR spectra were obtained on an UR-20 instrument.…”