with carbons resonating at δ 55.5 (C-9″/OCH3) and 33.5 (N-
11″/CH3), respectively. The N-methyl protons (δ 4.09)
showed HMBC cross-peaks with the signals at C-10a″ (δ
142.1) and C-11a″ (δ 136.0). These HMBC spectral data
suggested the substitution of a methyl group at N-11″. H-7″ (δ
7.93) and H-10″ (δ 6.98) exhibited HMBC correlations with C-
8″ (δ 115.4), C-9″ (δ 156.3), and C-10a″ (δ 142.1). These
NMR spectroscopic data and the absence of C-10 and C-8″
protons in the 1
H NMR spectrum indicated the linkage of two
carbazole moieties through a C-8″−C-10 single bond as
reported in bismahanine.14 Compound 3 showed a mirror
image Cotton effect couplet (positive at 239 nm and negative at
221 nm) compared to those of 1 and 2, indicating that 3 has an
aS-biphenyl configuration.15 On the basis of these spectroscopic
studies, the structure of 3, a new dimeric carbazole
alkaloid, bisgerayafoline C, was defined as 3,3′-bis[(E)-3,7-
with carbons resonating at δ 55.5 (C-9″/OCH3) and 33.5 (N-11″/CH3), respectively. The N-methyl protons (δ 4.09)showed HMBC cross-peaks with the signals at C-10a″ (δ142.1) and C-11a″ (δ 136.0). These HMBC spectral datasuggested the substitution of a methyl group at N-11″. H-7″ (δ7.93) and H-10″ (δ 6.98) exhibited HMBC correlations with C-8″ (δ 115.4), C-9″ (δ 156.3), and C-10a″ (δ 142.1). TheseNMR spectroscopic data and the absence of C-10 and C-8″protons in the 1H NMR spectrum indicated the linkage of twocarbazole moieties through a C-8″−C-10 single bond asreported in bismahanine.14 Compound 3 showed a mirrorimage Cotton effect couplet (positive at 239 nm and negative at221 nm) compared to those of 1 and 2, indicating that 3 has anaS-biphenyl configuration.15 On the basis of these spectroscopicstudies, the structure of 3, a new dimeric carbazolealkaloid, bisgerayafoline C, was defined as 3,3′-bis[(E)-3,7-
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