تفاعل #160866

معادلة التفاعل

hydrochloric acid

tert-butylcarbazate

2,5-dimethoxytetrahydrofuran

HCl

sodium bicarbonate

→

product

المردود 43.6%

Pyrrol-1-yl-carbamic acid tert-butyl ester

المردود 43.6%

المذيبات

1,4-dioxane

diethyl ether

CH3OH

ظروف التفاعل

المعالجة

1. 1
   أخرىA flask (fitted with a Dean-Stark trap)
2. 2
   workup.WAITAs the reaction progressed over several hours
3. 3
   درجة الحرارةto reflux
4. 4
   أخرىAs methanol collection
5. 5
   أخرىreaction completion
6. 6
   درجة الحرارةHeating
7. 7
   درجة الحرارةto cool somewhat
8. 8
   ترشيحThe quenched mixture was filtered through a sintered-glass funnel
9. 9
   تركيزconcentrated in vacuo
10. 10
    أخرىto leave an orange, semi-solid residue
11. 11
    ترشيحthe nearly colorless solids were collected by suction filtration
12. 12
    غسيلwashed with hexane
13. 13
    أخرىair-dried

الإجراء التجريبي

A flask (fitted with a Dean-Stark trap) containing a stirred solution of tert-butylcarbazate (100, 0.757 mol), 2,5-dimethoxytetrahydrofuran (108 g, 0.832 mol) and 2 N HCl (10 mL) in 1,4-dioxane (700 mL) was heated under nitrogen at 90° C. As the reaction progressed over several hours, the solution changed from pale yellow to orange and began to reflux. The reaction was monitored by the amount of distillate collected in the D/S trap (primarily CH3OH, 2 moles/1 mole reagent). As methanol collection approached the theoretical amount (50 mL) a sample was analyzed by TLC (silica gel, 1:3 EtOAc/hexane, ninhydrin stain) to confirm reaction completion. Heating was shut off and the reaction was allowed to cool somewhat before adding saturated sodium bicarbonate solution (˜25 mL) to neutralize the hydrochloric acid. The quenched mixture was filtered through a sintered-glass funnel and concentrated in vacuo to leave an orange, semi-solid residue. The residue was suspended in diethyl ether (minimum volume) and the nearly colorless solids were collected by suction filtration, washed with hexane and air-dried to afford 60.2 g (40%) of product. A second crop (yellow-tan solids) from the mother liquors was isolated: 29.0 g, (19%). Additional material which was present in the mother liquors could be recovered by silica gel chromatography to increase the yield. 1H-NMR (CD3OD): δ 10.23 (br s, 1H), 6.66 (t, 2H, J=2.2 Hz), 5.94 (t, 2H, J=2.2), 1.42 (s, 9H); MS: GC/MS (+esi): m/z=182.9 [MH]+

المصدر