NMR analysis and crystal structure of hydroxyclerodanes from Mexican Salvia species

Hydroxy-neo-Clerodanes and 5,10-seco-neo-Clerodanes from Salvia decora

“…Interestingly, the chemical shift for OH-8 (δ H 5.92 ppm) when recorded in DMSO-d 6 was in agreement with the empiric rules established by Bautista and coworkers, which describe important 1 H NMR features for assigning the absolute configuration at C-4, C-8, and C-10 in hydroxy-neo-clerodanes that bear a tertiary alcohol at these positions. 29 Even when quaternary carbons were not visible in the APT spectra (Figure S26, Supporting Information), their presence was evident in the HMBC experiment (Figure S29, Supporting Information). Consequently, compound 2 was assigned as 1-dehydro-6β,8α-dihydroxysalviarin.…”

“…The molecular formula of compound 2 was established as C 20 H 20 O 7 on the basis of its HRESIMS spectrum, which displayed a peak at m / z 373.1279 [M + H] + (calcd for C 20 H 20 O 7 + H, 373.1282). The 1 H and APT NMR spectra for compound 2 (Table , Figures S25 and S26, Supporting Information) were almost identical to those recorded for 1 and related analogues previously isolated from Mexican Salvia species. , The most evident difference found was the deshielding of C-8, which shifted from 44.7 ppm in 1 to 73.1 ppm in 2 and is attributed to an oxygenated function at this position. The absolute configuration of 2 was established as 4 R , 5 S , 6 R , 8 R , 9 R , 12 R , by comparison of its experimental ECD curve with that of 1 (Figure ) and based on the NOESY correlation observed between OH-8 and H 3 -20 (Figure S30, Supporting Information).…”

“…The absolute configuration of 2 was established as 4 R , 5 S , 6 R , 8 R , 9 R , 12 R , by comparison of its experimental ECD curve with that of 1 (Figure ) and based on the NOESY correlation observed between OH-8 and H 3 -20 (Figure S30, Supporting Information). Interestingly, the chemical shift for OH-8 (δ H 5.92 ppm) when recorded in DMSO- d 6 was in agreement with the empiric rules established by Bautista and co-workers, which describe important 1 H NMR features for assigning the absolute configuration at C-4, C-8, and C-10 in hydroxy- neo -clerodanes that bear a tertiary alcohol at these positions . Even when quaternary carbons were not visible in the APT spectra (Figure S26, Supporting Information), their presence was evident in the HMBC experiment (Figure S29, Supporting Information).…”

Amarisolide F, an Acylated Diterpenoid Glucoside and Related Terpenoids from Salvia amarissima

“…These assignments were supported by analysis of the 1 H and 13 C NMR data (Table ), which indicated the presence of a monosubstituted furan ring (δ C 128.4, C-13; δ H 8.15, br s, H-16; 7.44, d, J = 5.5 Hz, H-15; 6.77, br s, H-14) and an 18,19-γ-lactone (δ C 174.9, C-18, 71.7, C-19; δ H 4.94, d, J = 8.2 Hz, H-19α; 4.37, d, J = 8.2 Hz, H-19β). Additional signals in the 1 H and 13 C NMR spectra of 1 at δ H 6.01 (d, J = 10.4 Hz) and 5.70 (br d, J = 10.4 Hz) and δ C 76.8 (C) and 75.4 (C) were assigned to H-1 (δ C 129.4), H-2 (δ C 124.7), C-10, and C-4, respectively, and suggested the presence of a Δ 1(2) double bond, together with two tertiary hydroxy groups at C-4 and C-10, as has been described for amarissinin C ( 5 ) and infuscatin . The signals for the glycosidic moiety were resolved and assigned by the identification of the anomeric carbon at δ C 93.7 (CH, C-1′), its HSQC correlation with the anomeric proton (δ H 5.46, d, J = 8.2 Hz, H-1′), and the subsequent analysis of the COSY and HSQC spectra of the resulting spin system (Table ).…”

“…(2) double bond, together with two tertiary hydroxy groups at C-4 and C-10, as has been described for amarissinin C (5) and infuscatin. 11 The signals for the glycosidic moiety were resolved and assigned by the identification of the anomeric carbon at δ C 93.7 (CH, C-1′), its HSQC correlation with the anomeric proton (δ H 5.46, d, J = 8.2 Hz, H-1′), and the subsequent analysis of the COSY and HSQC spectra of the resulting spin system (Table 1). 12 The coupling constants (8.2−9.3 Hz) for this sugar moiety (Table 1) suggest trans-diaxial dispositions of all the involved protons in the spin system, as is common for a β-glucopyranoside.…”