Реакция #214739

Уравнение реакции

1-benzyloxy-4-(1,3-dithian-2-yl)-butan-2-one

ethylene glycol

p-toluenesulfonic acid

→

1-benzyloxy-2,2-ethylenedioxy-4-(1,3-dithian-2-yl)-butane

Растворители

benzene

Условия реакции

Обработка

1. 1
   Другоеgives a mixture which
2. 2
   Концентрированиеis concentrated to 500 ml in vacuo
3. 3
   workup.ADDITIONAfter the addition of sodium carbonate (10 g)
4. 4
   Другоеthe mixture is then partitioned between ether (300 ml) and brine (300 ml)
5. 5
   ЭкстракцияThe aqueous phase is extracted with ether (600 ml)
6. 6
   Промывкаthe combined extracts are washed with 0.05% sodium carbonate (1.2 l)
7. 7
   Фильтрацияfiltered
8. 8
   Другоеthrough phase-separating paper
9. 9
   Сушкаdried (sodium sulfate)
10. 10
    ДругоеThe solvent is removed in vacuo
11. 11
    Другоеto give a residue (102.15 g; 99%)
12. 12
    ДругоеA 200 mg portion of the residue is purified on Quantagram PQ1F plates (chloroform)

Методика

Treatment of 1-benzyloxy-4-(1,3-dithian-2-yl)-butan-2-one (89.8 g) in benzene (3.5 l) with distilled ethylene glycol (220 ml) and p-toluenesulfonic acid (11.7 g) at reflux temperature in a Dean-Stark apparatus for 18 hours gives a mixture which is concentrated to 500 ml in vacuo and allowed to stir for one hour. After the addition of sodium carbonate (10 g), the mixture is then partitioned between ether (300 ml) and brine (300 ml). The aqueous phase is extracted with ether (600 ml) and the combined extracts are washed with 0.05% sodium carbonate (1.2 l), filtered through phase-separating paper and dried (sodium sulfate). The solvent is removed in vacuo to give a residue (102.15 g; 99%). A 200 mg portion of the residue is purified on Quantagram PQ1F plates (chloroform) to give 1-benzyloxy-2,2-ethylenedioxy-4-(1,3-dithian-2-yl)-butane (180 mg); ir (heat) C=O absent; nmr (CDCl3,δ) 1.92 (m, 6H, CCH2CH2CH and ##STR9## 2.83 (m, 4H, SCH2CH2CH2S), ##STR10## 3.93 (s, 5H, OCH2CH2O and --CH<), 4.55 (s, 2H, φCH2O), 7.28 (s, 5H, φCH2O).

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