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

HRID 1671671Notes

Reaction equation

HRID 1671671 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

Commercially available 3-hydroxy-benzoic acid methyl ester (47) is alkylated with propargyl bromide in the presence of K2CO3 to give phenylether (48) which is cyclized to the chromen derivative (49) by heating to reflux in N,N-diethylaniline. The carboxylic ester is saponified by treatment of (49) with NaOH in MeOH/water and the obtained chromen derivative (50) is hydrogenated in presence of a palladium catalyst to give the desired acid (51). The corresponding chroman-8-carboxylic acid derivatives are synthesized by reduction of commercially available 4-chromanone (52) with zinc in acetic acid and subsequent ortho-metalation of the intermediate chroman derivative (53) with n-BuLi and trapping with carbon dioxide to give the desired acid (54).

Sources & evidence

ORD record
ord-aa34886488084e479bff948017d22644
Source dataset
uspto-grants-2011_08
Patent number
US07994336B2

Reaction notes

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