Synthetic and stereochemical studies on phthalideisoquinoline hemiacetals

Rozwadowska, Maria D.; Matecka, Dorota

doi:10.1002/jlac.199119910148

Cited by 5 publications

(2 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The early attempt to generate (±)-egenine was completed by LiAlH 4 reduction of (±)-bicuculline, which resulted in only one anomeric hemiacetal . It was reported that the anomeric form was likely to be stabilized by an intramolecular hydrogen bond, and the absolute configuration of (+)-egenine at C-7′ was then defined as R . This structural assignment was later verified by single-crystal X-ray crystallography of (−)-egenine, and the assumed hydrogen bond was observed .…”

mentioning

confidence: 99%

“…The absolute configurations of C-1 and C-9 were initially determined by chemical degradation studies, yet the configuration of the C-7′ anomeric center was unreported for some time . The early attempt to generate (±)-egenine was completed by LiAlH 4 reduction of (±)-bicuculline, which resulted in only one anomeric hemiacetal . It was reported that the anomeric form was likely to be stabilized by an intramolecular hydrogen bond, and the absolute configuration of (+)-egenine at C-7′ was then defined as R .…”

mentioning

confidence: 99%

See 1 more Smart Citation

Phthalideisoquinoline Hemiacetal Alkaloids from Corydalis decumbens That Inhibit Spontaneous Calcium Oscillations, Including Alkyl Derivatives of (+)-Egenine That Are Strikingly Levorotatory

et al. 2019

View full text Add to dashboard Cite

The new phthalideisoquinoline hemiacetal alkaloids (2−7) and the known analogues (1 and 8) were isolated from the bulbs of Corydalis decumbens. The new compounds were characterized by analysis of their NMR spectroscopic data, chemical degradation syntheses, X-ray crystallography, and comparison of experimental and calculated ECD data. All the isolates were screened in vitro for inhibitory activity of spontaneous calcium oscillations in primary cultured neocortical neurons. Compounds 1−3 and 5−7 were found to be active in the suppression of spontaneous calcium oscillations with IC 50 values of 6.8, 5.6, 11.6, 10.2, 8.3, and 3.1 μM, respectively. It was also observed that the presence of hydroxy, methoxy, and ethoxy groups at the remote stereogenic center C-7′ of some isolated phthalideisoquinoline hemiacetal alkaloids could alter the preferred conformation and invert the sign of optical rotation, rather than this resulting from configurational isomerism at C-1 or C-9, and that the 3 J 1,9 coupling constants of these analogues varied accordingly. For example, compounds 1 and 6 are levorotatory, despite these molecules having the same carbon skeleton and absolute configuration as (+)-egenine. This emphasizes the potential risk of incorrectly assigning absolute configuration based only on observed coupling constants or optical rotation when comparing the data of new compounds with literature values for known analogues, especially within this class of molecules.

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%