First direct kinetic measurement of i-C4H5 (CH2CHCCH2) + O2 reaction: Toward quantitative understanding of aromatic ring formation chemistry

2020 ◽  
Author(s):  
Arkke J. Eskola ◽  
Timo T. Reijonen ◽  
Timo T. Pekkanen ◽  
Petri Heinonen ◽  
Satya P. Joshi ◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Ring Formation ◽  
Kinetic Measurement ◽  
Quantitative Understanding

First aromatic ring formation by the radical-chain reaction of vinylacetylene and propargyl

2021 ◽  
Vol 225 ◽  
pp. 524-534
Author(s):  
Hanfeng Jin ◽  
Lili Xing ◽  
Dapeng Liu ◽  
Junyu Hao ◽  
Jiuzhong Yang ◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Ring Formation ◽  
Chain Reaction ◽  
Radical Chain ◽  
Radical Chain Reaction

Biosynthesis of Daphnetin in Daphne mezereum L.

1986 ◽  
Vol 41 (3) ◽  
pp. 247-252 ◽  
Author(s):  
Stewart A. Brown
Keyword(s):  
Caffeic Acid ◽  
Aromatic Ring ◽  
Lactone Ring ◽  
Ring Formation ◽  
Coumaric Acid ◽  
Tracer Experiments

Shoots of Daphne mezereum synthesized daphnetin (7,8-dihydroxycoumarin) more efficiently from [2-14C]umbelliferone (7-hydroxycoumarin) than from [2-14C]p-coumaric acid, and [2-14C]caffeic acid was more poorly utilized still. These findings do not support the idea of derivation of daphnetin via hydroxylation of the caffeic acid ring at the 2 position, followed by lactone ring formation; instead they are consistent with the concept of daphnetin formation by an additional hydroxylation of umbelliferone at C-8. Umbelliferone was recovered with little l4C dilution from emulsin-hydrolysed extracts of shoots fed labelled umbelliferone, and TLC of extracts from untreated shoots revealed two substances yielding umbelliferone on hydrolysis. Evidence is presented from TLC and HP LC analysis that one of these is skimmin (7-O-β-ᴅ -glucosylumbelliferone), not previously reported from Daphne. The tracer experiments further support the theory that umbelliferone is the general precursor of coumarins bearing two or more hydroxyl functions on the aromatic ring.

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