Journal
JOURNAL OF ORGANIC CHEMISTRY
Volume 88, Issue 19, Pages 13490-13503Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.joc.3c00950
Keywords
-
Categories
Ask authors/readers for more resources
This study discovered novel trimeric and tetrameric proanthocyanidins (PACs) with unprecedented benzoquinone motifs. Comprehensive spectroscopic analysis, including NMR and ECD, provided vital stereochemical information. This is the first indication that PACs may achieve structural diversity through oxidative oligomerization and post-oligomerizational modifications.
Proanthocyanidins (PACs) are complex flavan-3-ol polymers with stunning chemical complexity due to oxygenation patterns, oxidative phenolic ring linkages, and intricate stereochemistry of their heterocycles and inter-flavan linkages. Being promising candidates for dental restorative biomaterials, trace analysis of dentin bioactive cinnamon PACs now yielded novel trimeric (1 and 2) and tetrameric (3) PACs with unprecedented o- and p-benzoquinone motifs (benzoquinonoid PACs). Challenges in structural characterization, especially their absolute configuration, prompted the development of a new synthetic-analytical approach involving comprehensive spectroscopy, including NMR with quantum mechanics-driven H-1 iterative functionalized spin analysis (HifSA) plus experimental and computational electronic circular dichroism (ECD). Vital stereochemical information was garnered from synthesizing 4-(2,5-benzoquinone)flavan-3-ols and a truncated analogue of trimer 2 as ECD models. Discovery of the first natural benzoquinonoid PACs provides new evidence to the experimentally elusive PAC biosynthesis as their formation requires two oxidative post-oligomerizational modifications (POMs) that are distinct and occur downstream from both quinone-methide-driven oligomerization and A-type linkage formation. While Nature is known to achieve structural diversity of many major compound classes by POMs, this is the first indication of PACs also following this common theme.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available