Phosgene → 4,5-dihydro-5-methyl-6-[p-(1-methylprop-2-ynyloxycarbonylamino)-phenyl]-3(2H)-pyridazinone

HRID 1649101Notes

Reaction equation

[CH3:1][CH:2]([OH:5])[C:3]#[CH:4].[C:6](Cl)(Cl)=[O:7].[NH2:10][C:11]1[CH:16]=[CH:15][C:14]([C:17]2[CH:18]([CH3:24])[CH2:19][C:20](=[O:23])[NH:21][N:22]=2)=[CH:13][CH:12]=1>CCOCC>[CH3:24][CH:18]1[C:17]([C:14]2[CH:15]=[CH:16][C:11]([NH:10][C:6]([O:5][CH:2]([CH3:1])[C:3]#[CH:4])=[O:7])=[CH:12][CH:13]=2)=[N:22][NH:21][C:20](=[O:23])[CH2:19]1

Participants

Conditions

Temperature: -10 °C

Procedure

3.5 g (49.9 millimoles) of 1-methylprop-2-ynol are added dropwise to a stirred solution of 9.9 g (100 millimoles) of phosgene in 100 ml of absolute ether at -10° C. The reaction solution is then stirred for 1 hour at -10° C. followed by one hour at room temperature, and the excess phosgene is removed by means of a dry stream of nitrogen, after which the ether is removed under reduced pressure at room temperature. The 1-methylprop-2-ynyl chloroformate which is left (5.9 g) is reacted with 5.0 g (24.6 millimoles) of 6-(p-aminophenyl)-4,5-dihydro-5-methyl-3(2H)-pyridazinone by the method described in Example 31. The reaction mixture is also worked up as described in Example 31. After recrystallizing the product first from ethanol/water, then from ethyl acetate/petroleum ether and finally from dimethylformamide/water, 1.7 g (23% of theory) of 4,5-dihydro-5-methyl-6-[p-(1-methylprop-2-ynyloxycarbonylamino)-phenyl]-3( 2H)-pyridazinone are obtained as colorless crystals of melting point 206°-207° C.

Workup

waitfollowed by one hour at room temperature
customthe excess phosgene is removed by means of a dry stream of nitrogen
customafter which the ether is removed under reduced pressure at room temperature
waitThe 1-methylprop-2-ynyl chloroformate which is left (5.9 g)
customAfter recrystallizing the product first from ethanol/water

Sources & evidence

ORD record: ord-a8a7ca19bc8648dd8ea81dd6ec1ce04a
Source dataset: uspto-grants-1983_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US04415571

Reaction notes

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