Реакция #969853

Уравнение реакции

(Z)-4-(3-carboxy-2-sulfopropylamino)-4-oxobut-2-enoic acid

DMA

HMDS

→

title product

Выход 75.0%

4-(2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)-3-sulfobutanoic acid

Выход 75.0%

Растворители

toluene

Условия реакции

Обработка

1. 1
   Температураwas heated
2. 2
   Другоеreached at 80° C.
3. 3
   ТемператураThe mixture was continued heated to 115˜125° C.
4. 4
   Другоеtoluene was collected through Dean-Stark trap
5. 5
   workup.WAITDuring this period
6. 6
   workup.ADDITION2×20 ml of dry toluene was added
7. 7
   ТемператураThen the mixture was cooled
8. 8
   workup.ADDITION1 ml of 1:10 HCl (conc)/CH3OH was added
9. 9
   Другоеevaporated
10. 10
    Другоеpurified on SiO2 chromatography
11. 11
    Промывкаeluted with 1:5:0.01 CH3OH/CH2Cl2/HAc

Методика

(Z)-4-(3-carboxy-2-sulfopropylamino)-4-oxobut-2-enoic acid (450 mg, 1.60 mmol) in mixture of 10 ml of dry DMA and 50 ml of dry toluene was heated. After the temperature reached at 80° C., HMDS (hexamethyldisilazane, 1.80 ml, 8.63 mmol,) and ZnCl2 (3.2 ml, 1.0 M in diethyl ether) were added. The mixture was continued heated to 115˜125° C. and toluene was collected through Dean-Stark trap. The reaction mixture was fluxed at 120° C. for 6 h. During this period, 2×20 ml of dry toluene was added to keep the mixture volume around 8˜10 ml. Then the mixture was cooled, 1 ml of 1:10 HCl (conc)/CH3OH was added, evaporated, purified on SiO2 chromatography eluted with 1:5:0.01 CH3OH/CH2Cl2/HAc to afford 315 mg (75%) of the title product. 1H NMR (DMF-d7) 6.96 (s, 2H), 4.04 (dd, 1H, J=4.3, 13.8 Hz), 3.47 (m, 1H), 3.23 (dd, 1H, J=7.4, 14.7 Hz), 2.99 (dd, 1H, J=3.3, 16.8 Hz), 2.35 (dd, 1H, J=8.1, 16.9 Hz); 13C NMR 173.58, 172.18, 135.54, 54.61, 40.24, 32.43, ESI MS m/z− 261.70 (M−H).

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