Umbellic acid

Names
Preferred IUPAC name (2E)-3-(2,4-Dihydroxyphenyl)prop-2-enoic acid
Other names 2,4-Dihydroxycinnamic acid (E)-2,4-Dihydroxycinnamic acid (2E)-3-(2,4-Dihydroxyphenyl)acrylic acid
Identifiers
CAS Number	99699-42-0 Y 614-86-8 (non-specific) Y
3D model (JSmol)	Interactive image
ChemSpider	393925
ECHA InfoCard	100.221.943
PubChemCID	446611
UNII	U8G3LS2JEX Y
InChI InChI=1S/C9H8O4/c10-7-3-1-6(8(11)5-7)2-4-9(12)13/h1-5,10-11H,(H,12,13)/b4-2+ Key: HGEFWFBFQKWVMY-DUXPYHPUSA-N
SMILES C1=CC(=C(C=C1O)O)C=CC(=O)O
Properties
Chemical formula	C9H8O4
Molar mass	180.159 g·mol−1
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). Infobox references

Umbellic acid (2,4-dihydroxycinnamic acid) is ahydroxycinnamic acid. It is an isomer ofcaffeic acid.

It is a precursor in theumbelliferone biosynthesis pathway. Umbelliferone is aphenylpropanoid and as such is synthesized fromL-phenylalanine, which in turn is produced via theshikimate pathway. Phenylalanine is lysated intocinnamic acid, followed byhydroxylation bycinnamate 4-hydroxylase to yield4-coumaric acid. The 4-coumaric acid is again hydroxylated by cinnamate/coumarate 2-hydroxylase to yield 2,4-dihydroxy-cinnamic acid followed by a bond rotation of the unsaturated bond adjacent to thecarboxylic acid group. Finally an intramolecular attack from the hydroxyl group of C2' to the carboxylic acid group closes the ring and forms thelactone umbelliferone.

 ${\displaystyle \stackrel{PAL}{\to }}$  ${\displaystyle \stackrel{C4H}{\to }}$  ${\displaystyle \stackrel{C2H}{\to }}$  ${\displaystyle ⟶}$ 

The enzyme4-hydroxycinnamate decarboxylase, induced in bacteria species such asKlebsiella oxytoca, works also with p-coumaric acid analogs such as E-2,4-dihydroxycinnamic acid.^[1]

The dictionary definition ofumbellic acid at Wiktionary

• Hydroxycinnamic acids
• Resorcinols
• Vinylogous carboxylic acids

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