Diethyl Oxalate → 4,5-Dihydro-5,8-dimethyl-4-oxopyrano[3,2-b]indole-2-carboxylic acid

HRID 1448893Notes

Reaction equation

HRID 1448893 reaction equation
[CH3:1][C:2]([C:4]1[N:5]([CH3:15])[C:6]2[C:11]([C:12]=1[OH:13])=[CH:10][C:9]([CH3:14])=[CH:8][CH:7]=2)=[O:3].[Na].[C:17](OCC)(=O)[C:18]([O:20]CC)=[O:19].[Na][Na]>C(O)C>[CH3:15][N:5]1[C:6]2[CH:7]=[CH:8][C:9]([CH3:14])=[CH:10][C:11]=2[C:12]2[O:13][C:17]([C:18]([OH:20])=[O:19])=[CH:1][C:2](=[O:3])[C:4]1=2

Participants

6

Reactant 4

HCID 7268Diethyl OxalateHCID 141233DisodiumHCID 5360545SodiumHCID 125113281,5-dimethyl-3-hydroxy-1H-indol-2-yl methyl ketone

Product 1

HCID 126284314,5-Dihydro-5,8-dimethyl-4-oxopyrano[3,2-b]indole-2-carboxylic acid

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

In a manner analogous to that of Example 14, 8.2 g (0.040 mole) of 1,5-dimethyl-3-hydroxy-1H-indol-2-yl methyl ketone (Example 12) was reacted with sodium metal (3.7 g, 0.16 mole) and diethyl oxalate (21.5 g, 0.20 mole) in 200 ml absolute ethanol. The red disodium salt intermediate was then converted to the title compound as described in Example 17. Two recrystallizations of the final product from DMF-water yielded yellow needles of mpt. 290°.

Sources & evidence

ORD record
ord-9af3b0d6c54644269bdf56a9b59c66e0
Source dataset
uspto-grants-1980_02
Patent number
US04188326

Reaction notes

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