Carbon Dioxide → 3,4-Dihydro-2H-1-benzopyran-8-carboxylic acid

HRID 560220Notes

Reaction equation

HRID 560220 reaction equation
[O:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[C:4](=O)[CH2:3][CH2:2]1.O1C2C(=CC=CC=2)CCC1.[Li]CCCC.[C:27](=[O:29])=[O:28]>C(O)(=O)C.[Zn]>[O:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][C:9]=2[C:27]([OH:29])=[O:28])[CH2:4][CH2:3][CH2:2]1

Participants

7

Reactant 4

HCID 280Carbon DioxideHCID 68110ChromanoneHCID 136319ChromanHCID 178418339Butyllithium

Product 1

HCID 127011383,4-Dihydro-2H-1-benzopyran-8-carboxylic acid

Reagents, catalysts & solvents 2

HCID 23994ZincCatalystHCID 176Acetic AcidSolvent

Procedure

The synthesis of chroman-5-carboxylic acid derivatives started with the alkylation of 3-hydroxy-benzoic acid methyl ester (49; commercially available) with propargyl bromide in the presence of K2CO3 to give phenylether (50) which was cyclised to the chromen derivative (51) by heating to reflux in N,N-diethylaniline. The carboxylic ester was saponified by treatment of (51) with NaOH in MeOH and water and the obtained chromen derivative (52) was hydrogenated to give the desired acid (53). The corresponding chroman-8-carboxylic acid derivatives were synthesized by reduction of 4-chromanone (54; commercially available) with zinc in acetic acid and subsequent ortho-metalation of the intermediate chroman derivative (55) with n-BuLi and trapping with carbon dioxide to give the desired acid (56).

Sources & evidence

ORD record
ord-d4485fc646354d2ba68af33b8e8b1fac
Source dataset
uspto-grants-2011_11
Patent number
US08063099B2

Reaction notes

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