Abstract:Volumen XLII, Fasciculus VI (1959) -No. 223-224 2043 Das dabei gewonncne Rohprodukt wurde in Benzol gelost. Die Msung wurde durch wenig AI,O, filtriert und gab nach dem Verjagen des Losungsmittels im Vakuum 60 mg Riickstand. Aus Aceton-Chloroform-Ather 40 mg Kristalle vom Doppel-Smp. 95-105"/198-205°. Nach dem UmkristalIisieren wurden 28 mg kornige Kristalle vom DoppeI-Smp. 115-130°/200-2060 erhalten, die im Papierchromatogramm nur einetz Fleck gaben, der authentischem Diginatigenin (VI) entsprach. Misch-Smp.… Show more
“…Investigation for synthesizing dexamethasone acetate ( 25 ) from 3 began in 1988, 25 being the most widely used as an anti-inflammatory and antiallergic high-effect corticosteroid and the annual demand for it being about 5 tons worldwide. The selected synthetic route − was as depicted in Scheme . 1 …”
In the synthesis of dexamethasone acetate from tigogenin,
the
introduction of the 17α-hydroxy-16α-methyl and the
1,4-diene
moieties was improved. For the introduction of the
17α-hydroxy-16α-methyl moiety, the key step, epoxidation, was
accomplished in high yield with peracetic acid in a buffer
solution of sodium acetate and acetic acid (overall yield
from
17-ene substrate to 17α-hydroxy-16α-methyl
intermediate:
95.3%). Then the introduction of the 1,4-diene in the
A-ring
was greatly improved by bromination−dehydrobromination,
in which dehydrobromination proceeded smoothly in a
solvent
system that was a mixture of DMF and 6% of water (82.6%
isolated yield of 1,4-diene based on 3-oxo compound).
“…Investigation for synthesizing dexamethasone acetate ( 25 ) from 3 began in 1988, 25 being the most widely used as an anti-inflammatory and antiallergic high-effect corticosteroid and the annual demand for it being about 5 tons worldwide. The selected synthetic route − was as depicted in Scheme . 1 …”
In the synthesis of dexamethasone acetate from tigogenin,
the
introduction of the 17α-hydroxy-16α-methyl and the
1,4-diene
moieties was improved. For the introduction of the
17α-hydroxy-16α-methyl moiety, the key step, epoxidation, was
accomplished in high yield with peracetic acid in a buffer
solution of sodium acetate and acetic acid (overall yield
from
17-ene substrate to 17α-hydroxy-16α-methyl
intermediate:
95.3%). Then the introduction of the 1,4-diene in the
A-ring
was greatly improved by bromination−dehydrobromination,
in which dehydrobromination proceeded smoothly in a
solvent
system that was a mixture of DMF and 6% of water (82.6%
isolated yield of 1,4-diene based on 3-oxo compound).
“…3/3-Acetoxy-l7a-hydroxy-16/3-methyl-5a-pregnan-20-one (19). -Sodium hydride (0.2 g) was dissolved in dimethylformamide (4 ml) and (-butyl alcohol (3 ml) at ambient temperature.…”
Section: Methodsmentioning
confidence: 99%
“…Dehydration of 2,5-Dimethyl-4-isopropylidene-5-hydroxyhexan-3-one (19).-An 0.29-g sample of 19 was stirred in 25 ml of glacial acetic acid containing ten drops of concentrated sulfuric acid for 30 min. The reaction mixture was poured into 50 ml of water and extracted with three 25-ml portions of pentane.…”
“…Apparently an alkyl substituent in the 16position exerts a steric effect which renders the enol-acetylation procedure of Gallagher2 very impractical. 3 It has been found that the utilization of the 20-keto-21glyoxylate (III) offers an excellent route for the introduction of the 17a-hydroxy group. This method was based on the procedure of Hogg and Nathan.4…”
mentioning
confidence: 99%
“…Found: C, 68.64; H, 8.43. 3 -23-Diacetoxy-l 6 a-methyl-21 -normethyl-11 -oxo-17 (20), 22-choladieno-24(20)-lactone (IV).8 A mixture of 10 g. of the glyoxylic acid III, 100 ml. of acetic anhydride, and 500 mg. of 2,4-dinitrobenzenesulfonic acid was stirred at 25°f or 2 hr.…”
Reduction of a small sample of 17/3-hydroxyestrane-2one (Via) with sodium borohydride in ethanol water for 2 hr. afforded from benzene-petroleum ether hexagonal prisms, m.p. 208-210°, identical with the estrane 2a,17/3-diol (VIb) obtained above by mixed melting point and infrared spectra comparison.Estrane-176-ol (VIc). (a) By Huang-Minlon reduction of 176-hydroxyestrane-3-one (V). To a solution of 50 mg. of 17/3-hydroxyestrane-3-one (V) in 7 cc. of ethanol and 7 cc. of diethylene glycol 5 cc. of hydrazine hydrate was added.After refluxing for 30 min., 0.3 g. of solid potassium hydroxide was added and refluxing was continued for another 15 min. The condenser was then removed and the temperature of the solution was allowed to rise to 190°. Refluxing was then continued for 2.5 hr., at which point water was added and the mixture was extracted with ether. After washing with 5% hydrochloric acid, 5% sodium bicarbonate, and w'ater, the ether was dried and evaporated. The residue weighing 28 mg. was purified by sublimation at 90°, and subsequent crystallization from dilute ethanol. The estrane-17/3-ol (VIc) melted 130-133°( needles); [<*]d -8°.
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