Complete assignments of ¹H and ¹³C NMR data of three new dihydrophenanthrofurans from Pleione yunnanensis

Abstract

Three new dihydrophenanthrofurans, pleionesins A-C (1-3), together with two known dihydrophenanthrenes (4-5) were isolated from the tubers of Pleione yunnanensis (Rolfe). The complete (1)H and (13)C NMR spectra assignments of these compounds were carried out using 1D and 2D NMR experiments ((1)H, (13)C, selective 1D NOE, HSQC and HMBC).

Chemical Constituents from the Aerial Parts of Cyrtopodium paniculatum

“…In addition, the coupling constant of 5.4 Hz between H-11 and H-12 was in agreement with the reported literature values for the relative trans-configuration [57]. The absolute configurations of C-11 and C-12 were confirmed by CD determination: a negative Cotton effect at 284 nm suggested a 11S,12R form, which is consistent with previous reports [58,59]. The 3D structure was generated with an optimized energy minimization procedure using MM2, and suggested also a trans form as a 11S,12R.…”

“…The connection between the two units allows a new cyclization leading to a furan ring. It is noteworthy that this kind of dihydrophenanthrene derivative is considered as a chemotaxonomic marker for the species in the genus Pleione [59,73,[75][76][77], but has been also found in the genus Bulbophyllum [55] and Cremastra [54]. The last set of compounds were the dimers, occurring as either homo-(two units of 9,10-dihydrophenanthrene or phenanthrene) or as heterodimers (combinations of a 9,10-dihydrophenanthrene and a phenanthrene unit) having a C-C bond linkage.…”

Chemical Constituents and Biological Activity Profiles on Pleione (Orchidaceae)

“…The 27 was the first dihydrophenanthrene component connected with the bibenzyl isolated from the Pleione [15]. Three novel 9, 10-dihydrophenanthrofurans 29 – 31 were isolated by Dong in 2009 [21]. The properties of 9, 10-dihydrophenanthrofurans with a phenyl from the Pleione species were may be deemed to be a chemtaxonomic marker of this species.…”

“…Since then, the EtOAc fraction has been the key research part. Due to few researches focused on P. yunnanensis , Dong et al [21,22,23] carried out the phytochemical on P. yunnanensis in 2009, discovering 12 novel compounds and 12 known compounds. In addition, since the pseudobulbs of P. formosana have been used as the substitute of Shan-ci-gu in Taiwan Island, Shiao [24] performed chemical investigation on them in 2009 and isolated three novel compounds.…”

Shancigusins E‐I, five new glucosides from the tubers of Pleione yunnanensis

“…Many studies on the tubers of Pleione bulbocodioides , belonging to genus Pleione , had resulted in the isolation of several bibenzyls and dihydroxyphenanthrenes . Our previous phytochemical research on Pleione yunnanensis had led to the isolation of four new bibenzyl derivatives and three new dihydrophenanthrenes . This continuing studies on the same source resulted in the isolation of five new glucosides ( 1–5 ) along with 18 known compounds, including two bibenzyl glucosides ( 6–7 ), two bibenzyls ( 8–9 ), four 9,10‐dihydrophenanthrenes ( 10–13 ), one phenanthrene ( 14 ), one biphenanthrene ( 15 ), three glucosyloxybenzyl 2‐isobutylmalates ( 16–18 ), two sterols ( 19–20 ) and three other compounds ( 21–23 ).…”