Analysis of 1H-NMR spectra of cinnamaldehyde type model substances of lignin

Abstract

1H-NMR spectra of the following lignin model substances have been analyzed: cinnamaldehyde, 2-methoxycinnamaldehyde, 3-methoxycinnamaldehyde, 4-methoxycinnamaldehyde, 3,4-dimethoxycinnamaldehyde, 3-methoxy-4-hydroxycinnamaldehyde and 3,4,5-trimethoxycinnamaldehyde. From the NMR spectra analysis it follows that the studied compounds exist in solutions as trans isomers. Theoretical (PCILO) calculations in agreement with the NMR data have shown that the more stable conformer has trans orientation of C=O group with respect to the double bond of the conjugated side chain.

Chemical Constituents of Brazilian Propolis and Their Cytotoxic Activities

“…The EtOAc-soluble portion had the strongest cytotoxicity and was thus subjected to further investigation. After repeated column chromatography and preparative TLC on Si gel, the fraction afforded a new prenylated chromane derivative ( 1 ) along with 22 known compounds: 2,2-dimethyl-8-prenylchromene-6-propenoic acid ( 2 ); 2,2-dimethylchromene-6-propenoic acid ( 3 ); 2,2-dimethylchromene-6-carboxylic acid ( 4 ); artepillin ( 5 ); 4-dihydrocinnamoyloxy-3-prenylcinnamic acid ( 6 ); 4-hydroxy-3-prenylcinnamic acid ( 7 ); vanillin ( 8 ); coniferyl aldehyde ( 9 ); isocupressic acid ( 10 ); 15-acetoxyisocupressic acid ( 11 ); agathic acid ( 12 ); agathic acid 15-methyl ester ( 13 ); agathalic acid ( 14 ); cupressic acid ( 15 ); tremetone ( 16 ); viscidone ( 17 ); 12-acetoxyviscidone ( 18 ); betuletol ( 19 ); kaempferide ( 20 ); ermanin ( 21 ); 3,5,7-trihydroxy-4‘-methoxyflavanol ( 22 ); and dimeric coniferyl acetate ( 23 ) . To the best of our knowledge, compounds 4 , 7 , 12 − 19 , and 22 were isolated for the first time from propolis.…”

Chemistry in the Annonaceae, Part XXV. Sesquiterpenes from the Stem Bark of Cleistopholis glauca

“…The components of the remaining two bands were characterized as 3-methoxy-4-hydroxy-fnzw.f-cinnamaldehyde [7} (7) and 5-hydroxymethyl-2-furancarboxaldehyde [8] (8), both of which have been recorded previously as natural products but not from the Annonaceae.…”

Metabolite Profiling of Javanese Ginger Zingiber purpureum and Identification of Antiseizure Metabolites via a Low-Cost Open-Source Zebrafish Bioassay-Guided Isolation

“…The fractionation of the hexane extract yielded 15 fractions (A–O) (Figure B). Fractions A–E, H, I, L, and M have been unambiguously identified by HRMS and NMR (Figures S7–61, Supporting Information) and by comparison with literature as F-A, vanillin ( 1 ) and cassumunol H ( 2 ) in mixture; F-B, ferulaldehyde ( 3 ) and methyl vanillin ( 4 ) in mixture; F-C, 3,4-dimethoxycinnamaldehyde ( 5 ); F-D, ( E )-4-(3,4-dimethoxyphenyl)­but-3-en-1-ol ( 6 ); F-E, ( E )-4-(3,4-dimethoxyphenyl)­but-3-enyl acetate ( 7 ); F-H, ( E )-1-(3,4-dimethoxyphenyl)­buta-1,3-diene ( 8 ); F-I, ( E )-1-(3,4-dimethoxyphenyl)­but-1-ene ( 9 ); F-L, 3,4-bis (3,4-dimethoxyphenyl)-1,5-octadiene ( 10 ), trans -banglene ( 11 ) and cis -banglene ( 12 ) in mixture; F-M, 11 and 12 in mixture (Figure C). Compounds 1 – 9 , 11 , and 12 were already described in Z. purpureum , except for 10 which was described for the first time, although it has been reported as a product after pyrolysis of cis -1,2-bis­[( E )-3,4-dimethoxystyryl]­cyclobutane via Cope rearrangement …”