Abstract
AbstractFour new pyrrole alkaloids, methyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]propanoate (1), methyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]‐3‐(4‐hydroxyphenyl)propanoate (2), dimethyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]butanedioate (3), and dimethyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]pentanedioate (4), were isolated from the AcOEt extract of the fruits of Lycium chinense Miller (Solanaceae). The stereogenic center C(2) in the bulky N‐alkyl side chain in each of 1–4 seems to hold the H‐atoms of nearby CH2 groups, CH2(7′) and CH2(3) (if R≠H), leading to two different chemical shifts in the 1H‐NMR spectrum due to their diastereotopic characteristics. In the 1H‐NMR data of each of 2–4, the enhancement of HC(2) signal was inhibited by the R group, probably due to steric hindrance, and its chemical shift was influenced by the anisotropy effect. The structures of 1–4 were elucidated by analysis of various spectroscopic data, including 1D‐ and 2D‐NMR.
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