p-Toluenesulfonic acid → Eosin

HRID 894849Notizen

Reaktionsgleichung

Reaktionsgleichung von HRID 894849
C1(C)C=CC(S(O)(=O)=[O:8])=CC=1.[CH:12]1[CH:17]=[C:16]([C:18]2[C:32]3[C:27](=[C:28]([Br:35])[C:29]([O-:34])=[C:30]([Br:33])[CH:31]=3)[O:26][C:25]3[C:19]=2[CH:20]=[C:21]([Br:37])[C:22]([C:24]=3[Br:36])=[O:23])[C:15]([C:38]([O-:40])=[O:39])=[CH:14][CH:13]=1.[Na+:41].[Na+]>C1C=CC=CC=1>[CH:12]1[CH:17]=[C:16]([C:18]2[C:19]3[C:25](=[C:24]([Br:36])[C:22]([O-:23])=[C:21]([Br:37])[CH:20]=3)[O:26][C:27]3[C:32]=2[CH:31]=[C:30]([Br:33])[C:29]([C:28]=3[Br:35])=[O:34])[C:15]([C:38]([O-:40])=[O:39])=[CH:14][CH:13]=1.[Na+:41].[Na+:41].[CH3:32][C:27]1([CH2:28][CH3:29])[O:26][CH2:25][CH2:19][O:8]1

Komponenten

5

Edukt 2

HCID 6101p-Toluenesulfonic acidHCID 11048Eosin

Produkt 2

HCID 11048EosinHCID 610672-Ethyl-2-methyl-1,3-dioxolane

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 241BenzeneLösungsmittel

Versuchsvorschrift

Reaction of 40.0 g of norbornadiene and 13.2 g of paraformaldehyde in formic acid (480 ml) containing concentrated sulfuric acid (20 drops) gave 55.3 g of diformate i. Oxidation of diformate i (55.3 g) in 900 ml of acetone at ##STR8## 0° C. with 553 ml of standard Jones reagent provided 27.2 g of keto acid ii. Treatment of 21.5 g ii with 225 ml of 48% hydrobromic acid in 225 ml of glacial acetic acid at reflux gave 28.1 g of bromo acid 1 (R2 =H, R3 =O). Esterification of 1 (R2 =H, R3 =O) with ethereal diazomethane gave methyl ester of formula (1) wherein R2 =Me, and R3 =O. Ketalization of 16.1 g of keto ester 1 (R2 =Me, R3 =O) with 35.8 g of 2-methyl-2-ethyl-1,3-dioxolane in 150 ml of benzene containing 2.7 g of p-toluenesulfonic acid at 25° C. for 20 hours give 17.0 g of pure ketal ester of formula (1) wherein R2 =Me and R3 =--O(CH2)2O--. Fluorination of 4.66 g of ester 1 (R2 =Me, R3 =--O(CH2)2O--) via enolate formation [lithium disopropylamide, tetrahydrofuran, -78° C.] and slow addition of perchloryl fluoride (-40° C.) resulted in an 86% isolated yield of a pure mixture of the desired α-fluoro ester shown in formula (2) (Rf 0.41) [hexane-ethyl acetate (4:1)] and the isomeric α-fluoro ester shown in formula (3) (Rf 0.33 in a ratio of 1:1.). Chromatography on silica gel easily provided the α-fluoro ester of formula (2), which was reduced with lithium aluminum hydride in ether at 25° C. and dehydrobrominated with 1,5-diaza-bicyclo(5.4.0)undec-5-ene (10 equivalents) in refluxing toluene. An 84% yield of the pure alcohol shown in formula (4) M+ 200.0850 was obtained. As fluorination with perchloryl fluoride can be hazardous, safety precautions should be observed.

Quellen und Nachweise

ORD-Eintrag
ord-342cf83d342a4fc2b3e578c0823b855b
Quelldatensatz
uspto-grants-1981_08
Patentnummer
US04284794

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