Reaktion #459789

Reaktionsgleichung

triethylamine

diphenylmethyl 3-bromomethyl-7β-(2-thienylacetamido)-ceph-3-em-4-carboxylate

1-ethyltetrazoline-5-thione

hydrochloric acid

→

ester

Diphenylmethyl 3-(1-ethyltetrazol-5-ylthiomethyl)7β-(2-thienylacetamido)-ceph-3-em-4-carboxylate

Lösungsmittel

tetrahydrofuran

tetrahydrofuran

brine

ethyl acetate

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeto rise to ca. 20°
2. 2
   SonstigeThe organic phase was separated
3. 3
   Waschenwashed with 2N-hydrochloric acid, saturated sodium bicarbonate, water, and brine
4. 4
   Sonstigedried
5. 5
   Sonstigeevaporated to a foam (11.71 g)
6. 6
   SonstigeA solution of this foam in benzene (25 ml) was purified by chromatography on kieselgel (200 g), with benzene
7. 7
   Sonstigethe solvents evaporated in vacuo
8. 8
   workup.DISSOLUTIONThe residue was dissolved in methylene dichloride

Vorschrift

A solution of diphenylmethyl 3-bromomethyl-7β-(2-thienylacetamido)-ceph-3-em-4-carboxylate (11.67 g) and 1-ethyltetrazoline-5-thione (2.6 g) in dry tetrahydrofuran (150 ml) was stirred at 0° and a solution of triethylamine (2.8 ml) in tetrahydrofuran (25 ml) was added, dropwise, over 5 minutes. The resulting suspension was stirred for a further 25 minutes, during which time the temperature was allowed to rise to ca. 20°, and was then added, over 5 minutes, to a stirred mixture of 2N-hydrochloric acid (50 ml), water (350 ml), brine (350 ml), and ethyl acetate (600 ml). The organic phase was separated, and washed with 2N-hydrochloric acid, saturated sodium bicarbonate, water, and brine, and dried and evaporated to a foam (11.71 g). A solution of this foam in benzene (25 ml) was purified by chromatography on kieselgel (200 g), with benzene:ethyl acetate = 5:1 as eluant. Appropriate fractions were combined and the solvents evaporated in vacuo. The residue was dissolved in methylene dichloride, and the solution run into petroleum ether to give the ester as a pale-yellow, amorphous solid (8.585g, 68%); [α]D23 - 131° (c 0.97. CHCl3); λmax. (EtOH) 264 nm (ε 7,300), τ (CDCl3) values include 4.12 (7-H, dd, J 5 and 9 Hz.), 5.04 (6-H, d, J 5 Hz.), 5.83 (CH3CH2 --, q, J 7 Hz.), and 8.57 (CH3CH2 --, t, J 7 Hz.).

Quelle