DE1064060B - Process for the separation of a mixture of brominated and unbrominated allopregnan derivatives - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

PATENT 1 064

REGISTRATION DAY:

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL:

ISSUE OF
PATENT LETTERING:

kl. 12o 25/05

INTERNAT. KL. C 07 C

FEBRUARY 14, 1958

AUGUST 27, 1959 FEBRUARY 4, 1960

AGREES WITH EDITORIAL

1064 060 (G 2S917 IVb / 12 o)

The invention relates to a method for separating a mixture of a 4-bromo-4,5 a-dthydrosteroid-3-ketone the general formula

CH ₂ OR ₃

OH

in which R _{2 is} a hydroxyl radical or a keto oxygen _{atom and R 3 is} hydrogen or an acyl radical, and the corresponding 2-bromo-4,5α-dihydrosteroid-3-ketone and / or the corresponding non-brominated 4,5cr-dihydrosteroid-3-ketone. The bromine atoms have either a or / J corification.

The ring A of various allopregnan derivatives of physiological importance contains a 4 (5) position Double bond and a 3-position keto group, a structure that cannot be synthesized in a direct way can be achieved.

While mari in the monobromination of a 4,5 / J-dihydrosteroid-3-ketone the 4-bromo compound obtained, from which one introduces a double bond in the 4 (5) position by splitting off hydrogen bromide can, a 2-bromine compound is formed in the allele series. A well-known method of introduction a double bond in the 4 (5) position of a 4-5 α-dihydrosteroid-3-ketone is bromination to the 2,4-dibromo compound, reaction of this compound with sodium iodide to give one in the 4 (5) position unsaturated 2-iodo-steroid-3-ketone and subsequent removal of the iodine atom in the 2-position through reduction.

In German patent 1 002 346 the reduction of 2,4-dibromo-4,5 a-steroid-3-ketones to 4-bromo-4,5 described a-dihydrosteroid-3-ketones, which "by splitting off hydrogen bromide in the in Let the 4 (5) position unsaturated 3-ketones be transferred. However, this reduction becomes a mixture obtained that can be separated by fractional crystallization.

The inventive method is particularly suitable for the separation of steroid mixtures, such as they in the reduction of 2,4-dibromo-4,5α-dihydrosteroid-3-ketones to 4-bromo-4,5a-dihydrosteroid-3-ketones according to German patent 1,002,346. It will thus be an improvement in the preparation of the 4 (5) position unsaturated process for separating a mixture from brominated and unbrominated

Allopregnan derivatives

Patented for:

Glaxo Laboratories Limited,
Greenford, Middlesex (Great Britain)

Claimed priority:
Great Britain February 15, 1957 and February 6, 1958

Alan Gibson Long and William Graham,

Greenford, Middlesex (Great Britain),

have been named as inventors

Steroid-3-ketones from the corresponding 4,5a-dihydrosteroid-3-ketones achieved because it is difficult to isolate and purify the 4-bromine compound, since the compounds contained in the resulting mixture are structurally very close to one another.

It has now been found that the bromine-free 4,5 a-dihydrosteroid-3-ketones and the corresponding 2-Bromo-4,5a-dihydrosteroid-3-ketones easily form complexes with bisulfite ions in various aqueous Media are soluble, while the corresponding 4-bromo-4,5α-dihydrosteroid-3-ketones are difficult to achieve Form complexes. According to the invention, therefore, the mixture to be separated has a bisulfite ion supplying substance for the formation of water-soluble bisulfite complexes of the bromine-free and 2-bromine compounds implemented and then the unreacted 4-bromine compound of the mentioned water-soluble Bisulfite complexes separated by the differences in solubility in aqueous media.

The formation of the bisulfite complexes of the 2-bromo and the non-brominated compounds is preferred made in aqueous media. You can use water alone; however, one preferably uses Water together with a water-miscible organic solvent, as the bisulfite complexes, especially those of the 2-bromine compounds are not very soluble in pure water. The use of Mixtures of water and water-miscible organic solvent facilitate the separation.

909 706/340

Suitable water-miscible organic solvents are, for example, water-miscible alcohols, such as Methanol, ethanol, isopropanol, also dioxane or acetonitrile.

Where the reaction with the bisulfite ions is carried out in aqueous media, the unreacted 4-bromine compound can easily be separated off in solid form by simple filtration of the reaction mixture, the bisulfite addition compounds of 2-bromo-4,5a-dihydrosteroid-3-ketone in the filtrate and the corresponding non-brominated ketone remain. The substance which produces bisulfite ions can be a metabisulfite, for example a substance which contains the group S ₂ O ₅ . The alkali or ammonium metabisulphites are preferred because they have the desired water solubility. Sodium, potassium or ammonium metabisulphite are particularly preferred. It is known that metabisulphites give bisulphite ions in the presence of water.

The p _H, wherein the mixture of the steroid is reacted with the bisulfite ion providing substance is essential. Many steroids are known to be sensitive to extreme p _H values. Therefore, the reaction should be carried out at a pjj at which the steroid reactants are essentially stable and at which bisulfite ions can also exist. In general, a P ₁₁ WePt between 4 and 8 should be satisfactory.

According to a preferred embodiment of the invention, the mixture to be treated is in one water-miscible solvents such as acetonitrile, dioxane or ethanol suspended, the bisulfite ions delivering substance is added in aqueous solution and the mixture is reacted therewith. The the preferred water-miscible solvent is ethanol. The sodium metabisulfite concentration in Water should be chosen so that when mixed with ethanol in the chosen ratio no precipitate of the salt occurs. A concentration of 10 to 20% sodium metabisulphite is suitable for this.

According to another embodiment of the invention, the steroid mixture to be treated is first suspended in an aqueous, water-miscible organic solvent and then solid Bisulfite added.

So that the reaction proceeds at a useful rate, the reaction between the steroid mixture and the bisulfite ion-yielding compound should take place at somewhat elevated temperatures, for example at temperatures from 40 to 100 ^° C. or at temperatures up to the boiling point of the liquid solvent medium used. The reaction is generally carried out by heating at the temperature mentioned for 15 to 30 minutes. Once the bisulfite derivatives are formed, for example in aqueous ethanol, the mixture can be diluted with a fairly large volume of water without the bisulfite derivatives precipitating.

Since the formation of bisulfite complexes of ketones is a reversible reaction, it is generally desirable to use an excess of bisulfite over the amount theoretically required to so as to ensure the completeness of the reaction. Preferably an excess of 4 to 16 equivalents is used Bisulfite ions about the stoichiometrically required to treat the steroids in the mixture Amount used.

As already mentioned above, it is essential for the present invention that 2-bromo-4,5α-dihydro-steroid-3-ketones and 4,5a-dihydro-steroid-3-ketones easily form complexes with bisulfite ions, while 4-bromo-4,5 dihydro-steroid-3-ketones do not do this so easily. However, it is generally possible to use a bisulfite complex of the 4-bromine compound under difficult conditions to form, for example by using an extreme excess of bisulfite ions, extended reaction times and / or increased reaction temperatures. The relative ease with which the 2-bromine and non-brominated compound fertilizers form bisulfite complexes in comparison with the 4-bromine compound is so noticeable that it is in the In practice it is easy to select conditions in which the 2-bromine and / or non-brominated compounds react without disrupting the 4-room connections to be attacked.

Under certain circumstances it can be beneficial to filter off of the unreacted 4-bromo-steroid-3-ketone to add a filter aid, for example Kieselguhr. The 4-bromo-steroid-3-ketone can then be mixed with kieselguhr or another Filter aid can be extracted, for example by heating with ethyl acetate, filtering the hot Mix and cool the filtrate, followed by practical pure 4-bromo steroid-3-ketone is obtained. The 2-bromine and / or non-brominated compounds can from the dissolved bisulfite compounds by decomposition, for example with acid or a Alkali carbonate or bicarbonate solution. The obtained mixture of 2-bromo-4,5a-dihydro-steroid-3-ketone and / or the corresponding non-brominated ketone can then lead to 2,4-dibromo-4,5 a-dihydro-steroid-3-ketone are brominated, which can be returned to the process.

On the other hand, the 2-bromo-4,5 cr-dihydro-steroid-3-ketone for example, can also be reduced in the presence of the corresponding non-brominated ketone, so that the corresponding non-brominated ketone is obtained, which then becomes the starting material, the 2,4-dibromo-4,5a-dihydro-allosteroid-3-ketone can be brominated.

From the present representations it can be seen that those present in the original mixture recovered contaminating substances and returned to the process after appropriate treatment can be obtained, thereby obtaining a large yield of the desired 4-bromo compound can.

The process according to the invention is of particular value in the separation of 4-bromo-4,5a-dihydrocortisone and its esters from mixtures containing this compound in addition to 2-bromo-4,5a-dihydrocortisone and / or its ester and / or 4,5 a-dihydrocortisone and / or its ester. Such a separation is of particular importance in the production of cortisone and its esters from 2,4-dibromo-4,5 α-dihydrocortisone ester according to the method of German patent 1 002 346.

The following examples explain the process according to the invention.

example 1

Preparation of 4-bromo-5a-pregnane-17a-2 * l-diol-3, ll, 20-trione-21-acetate (4-bromine compound)

Bromination and rearrangement 100 g of finely divided 4.5 cm dihydrocortisone acetate were suspended in 1150 ml of glacial acetic acid with stirring and 80 ml of a solution of 6.3 η hydrogen bromide in Glacial acetic acid added. The suspension was cooled to 16 ° C and a solution of 26.4 ml of bromine in 800 ml of glacial acetic acid were added over a period of 8 minutes.

The coolant was removed and stirring continued for an additional 15 minutes. After that, the Air in the reaction vessel and in the reaction mixture displaced by carbon dioxide. That inert atmosphere was maintained for the remainder of the reaction.

Partial debromination

With continued vigorous stirring, 356 ml of an aqueous 1.74 normal chromium (II) chloride solution were added added over 85 minutes. The reaction was completed by stirring for an additional 15 minutes. 1200 ml of warm methylene chloride were then added, then from a dropping funnel 5 1 warm water of about 40 ° C within 5 minutes. The layers were separated and the aqueous phase extracted three times with 400 ml of warm methylene chloride each time. The first three extracts were combined and successively with 800 ml of water, 800 ml of saturated aqueous bicarbonate solution and washed again with 800 ml of water. The wash waters were sequentially with the fourth methylene chloride extract extracted again. The temperature remained at 35 to 40 ° C all the time held to prevent crystallization of the monobromides. The combined organic layers were evaporated to dryness under reduced pressure.

Separation of the 4-bromine compound by bisulfite

The resulting solid was suspended in 1200 ml of technical methyl alcohol and 1440 ml of 10 ^| oiigterwäßrigerNatrium-metaibisulfitlösungbei60 ° C treated ^0/15 minutes. The. Suspension was diluted with 3.6 l of water and cooled to room temperature. The solid was then removed by filtration through a layer of kieselguhr and washed twice with 200 ml of 70% aqueous technical methanol each time. The moist, solid cake was refluxed with 3.6 l of ethyl acetate for 30 minutes and the kieselguhr was separated off by hot filtration. The filtrate was concentrated to a volume of approximately 1 liter, and crystallization was completed at 0 ° C. overnight. The solid mass was filtered off, washed with a little ethyl acetate, dried and freed from the solvent in an oven at over 100 ° C. in vacuo.

Yield of 4-bromo-allopregnan-17a, 21-diol-3, ll, 20-trione-21-acetate: 58.4 g (48.5%); [a] _ß + 62 °.

The mother liquors from the crystallization were evaporated to dryness and the remaining solid mass with the recovered 2-bromine compound and the 4,5 a-dihydrocortisone acetate for debromination united.

Obtaining the 2-bromine compound and the 4,5 a-dihydrocortisone acetate

The filtrate was treated with 290 g of sodium bicarbonate and once with 1.5 liters and four times with each

30th

55 500 ml of ethyl acetate extracted. The first four extracts were combined and washed four times with 300 ml of water each time. The wash waters were extracted again with the fifth ethyl acetate extract. The combined ethyl acetate solutions were evaporated to dryness under reduced pressure. This material was combined with the solid obtained from the mother liquors of crystallization of the 4-bromine compound. . ·

Total yield: 52.5 g (44%, calculated as monobromide).

Production of 4,5 a-dihydrocortisone acetate

The crude solid product obtained above was in 800 ml of acetone, together with 44 g of tartaric acid and 130 g of sodium iodide dissolved. The mixture was refluxed for 1 hour, cooled and poured into a Mixture of 114 g of sodium bicarbonate and 42 g of sodium metabisulphite poured into 1.5 liters of water. Further 1.5 Ί water was added, the precipitated solid mass was removed by filtration and the product washed three times with 11 l of water each time. The wet cake was refluxed in boiling ethyl acetate dissolved and the excess solvent removed by distillation at atmospheric pressure until crystallization began. The mixture was cooled, last overnight at 0 ° C, and filtered. the solid mass was washed with a little ether and dried in vacuo at 100.degree.

Weight: 31.6g; [ _{α] β} + 110 ° (CHCl ₃ ), mp 229 to 232 ° C. The total yield of 4-bromine compound was 71% of theory.

Example 2

Use of other solvents, temperatures and bisulfites

1 g of a mixture consisting of equal parts of 2a-bromo-4,5a-dihydro-cortisone acetate ([a] o + 108 °) and 4a-bromo-4,5a-dihydro-cortisone acetate ([α] ρ + 61 °) was passed in the solvent at the temperature given in the table below is dissolved or suspended. A 10% solution of the bisulfite in water was added and the mixture is heated. The insoluble fraction was filtered off, washed twice with 25 ml of water and dried at 110 ° C. in vacuo, the crude 4a-bromine compound being obtained.

The aqueous filtrate was treated with 3 g of sodium bicarbonate and twice with 50 ml of methylene chloride extracted. The solvent was removed by distillation and the remaining solid residue in the Vacuum dried at 110 ° C. It consisted of the raw 2 α-B rom compound.

The following table shows the effect of changing the solvent system, the temperature, at which the separation was made and the bisulfite compound used.

solvent Vol.
[ml] Bisulfite compound Vol.
(10%,)
[ml] Tempe
rature
[ ⁰ C] time
[Minutes] Soluble
fraction
[G] Wd Insoluble
fraction
fe] Wd Methanol
Acetonitrile .....
Dioxane
Dioxane
Isopropyl alcohol
Ethanol
Ethanol 40
■ 25
25th
30th
20th
20th
20th Sodium metabisulphite
YY
YY
YY
YY
Potassium metabisulfite
Ammonium meta-
bisulfite 24
30th
30th
24
24
24
24 50
60
60
92
58
58
50 16
20th
15th
15th
15th
15th
15th 0.33
0.48
0.40
0.27
0.47
0.33
0.34 + 103 °
+ 96 °
+ 111 °
+ 105 °
+ 1.00 °
+ 97.5 °
. + 100 ° 0.67
0.5
0.53
0.36
0.51
0.6
0.7 + ■ 76 °
+ 77 °
+ 72 °
+ 77 °
+ 73 °
+ 79 °
+ 79.5 °

Example 3

Separation of 4-bromo-4,5a-dihydro-cortisone acetate from a mixture with the 2-bromine analog and

4,5a-dihydro-cortisone acetate g

6 g of 4-bromo-4,5a-dihydrocortisone acetate ([a] p + 61 ° (CHCl ₃ )) were mixed with 3 g of 2-bromo-4,5a _{-dihydrocortisone acetate ([a] ß +108} ° (CHCl ₃ )) and 3g 4,5a-dihydro-cortisone acetate ([a] ₀ + 115 ° (CHCl ₃ )) mixed '. 215 ml of ethanol were added and the mixture was refluxed to dissolve the solid components. 215 ml of 10% aqueous sodium metabisulfite was added and the mixture was held at 55 ° C for 15 minutes. 540 ml of ice water were then added and the mixture was stirred for 10 minutes. 6.78 g of crude product were filtered off and recrystallized from ethyl acetate. 6.09 g of practically pure 4-bromo-4,5a-dihydrocortisone acetate were obtained; [α] _D + 64.2 °, (CHCl ₃ ).

The dissolved part of the mixture was obtained by adding 40 g of sodium bicarbonate to the aqueous filtrate, Extraction of the released steroids with chloroform and distillation in "vacuum" recovered to dryness. The residue was treated with 7.5 g of tartaric acid and 22 g of sodium iodide in 200 ml of acetone and then Heat treated under reflux for 1 hour.

The mixture was cooled and the liberated iodine was reduced with a solution of 8 g of sodium bicarbonate and 3 g of sodium metabisulphite in 75 ml of water. The acetone was removed by vacuum distillation, the product was filtered off from the aqueous residue, dried and recrystallized from ethyl acetate, giving 4.95 g of 4.5 α-dihydrocortisone acetate, [α] _D + 109.8 °, mp 230 bis 232 ° C.

B e i s ρ i e 1 4

A solution of 20g of 5a-Pregnari-II / ?, 17a, 21-triol-3,20-dione-21-acetate in 200 ml of dry tetrahydrofuran was cooled to 5 ° C. and, with stirring, with a solution of 5 η hydrogen bromide in 2 ml of acetic acid treated. Then 16.15 g (2.06 mol) of bromine was added dropwise over 7 minutes. During the addition of the bromine, the temperature of the solution was raised by cooling the reaction vessel kept below 10 ° C from the outside. The solution was then heated to 20 ° C and at this Leave temperature for 25 minutes. 20 ml of water were then added, followed by 7 g of sodium bicarbonate in portions and finally added 0.5 g of sodium metabisulphite to the stirred mixture. the The lower, aqueous phase was separated off, the upper, organic phase with a solution of 8 g of sodium bicarbonate and washed 50 g of ammonium sulfate in 75 ml of water. The first aqueous phase was washed with 75 ml of tetrahydrofuran and the washing process repeated with the second aqueous phase. The organic phases were combined, stirred with 60 g of sodium sulfate for 1 hour, the sulfate through Filtration removed and washed four times with 30 ml of tetrahydrofuran each time. The united organic Phases were concentrated under reduced pressure and concentrated to an oil below 25 ° C.

The crude bromination product was taken up in 300 ml of glacial acetic acid and the solution was stirred at 17 ° C. under a carbon dioxide atmosphere; while 50.2 ml of 2.47 η chromium (II) chloride solution were added over the course of one hour. The mixture was poured into 1500 ml of ice water, stirred for 1 hour and filtered. A small portion of the raw, solid mass was dried in vacuo at 80 ° C; [α] _D + 53 ° (1% CHCl ₃ ). The remainder of the crude solid was taken up in 360 ml of ethanol under reflux and treated with a solution of 43 g of sodium metabisulphite in 430 ml of water. The mixture was stirred at 55 ° C. for 15 minutes and then ^{diluted with 1080 1} ml of ice water. After stirring an additional 10 minutes, the mixture was filtered and washed well with cold water. The crystalline bisulfite compound obtained was insoluble in chloroform, but soluble in 5% warm sodium metabisulfite solution. It was decomposed by shaking in a two-phase mixture of chloroform and saturated aqueous sodium bicarbonate solution. The Cfiloroform solution was distilled in vacuo at 28 ° C. It left a gummy mass which crystallized from methanol and prisms of 4-bromo-4,5a-dihydro-cortisone-21-acetate (1.85 g), mp 173 ° C (decomposition); [ct] _fl + 31.5 ° (10/0 CHCl ₃ ).

Analysis: C ₂₃ H ₃₃ O ₆ Br

Calculated (for 2CH ₃ OH) Br 14.56%;

found (for 2CH ₃ OH) Br 14.2%.

Claims (11)

Patent claims: 1. A method for separating a mixture of a 4-bromo-4,5 a-dihydro-steroid-3-ketone of general formula R. CH ₂ OR ₃ CO
-OH O = Br in which R _{2 is} a hydroxyl radical or a keto oxygen _{atom and R 3 is} hydrogen or an acyl radical, and the corresponding 2-bromo-4,5 ordihydrosteroid-3-ketone and / or the corresponding non-brominated 4,5a-dihydrosteroid-3-ketone , characterized in that this mixture with a bisulphite ion-supplying substance to form a water-soluble derivative of 2-bromo-4,5 a-dihydro-steroid-3-ketone and / or a water-soluble derivative of the corresponding non-brominated 4,5 a-dihydrosteroid-3 -ketone converts, separates the unreacted 4-bromo-4,5crdihydrosteroid-3-ketone from the water-soluble derivatives mentioned by differences in solubility in aqueous media and optionally the water-soluble derivative (s) for the recovery of 2- Bromo-4,5a-dihydrosteroid-3-ketone and / or unbrominated 4,5a-dihydrosteroid-3-ketone decomposed. 2. The method according to claim 1, characterized in that in the mixture to be separated Compounds contained are present as 21-acetates. 3. The method according to claim 1 or 2, characterized in that the reaction in one aqueous medium is carried out. 4. The method according to claim 3, characterized draws that the aqueous medium water or one of water and one miscible with water organic solvent is used. 5. The method according to claim 4, characterized in that as water-miscible organic Solvent a water-miscible alcohol, acetonitrile or dioxane is used. 6. The method according to claim 1 to S, characterized in that the supplying bisulfite ions Substance a metabisulphite, especially an alkali or ammonium metabisulphite, especially sodium metabisulphite is used. 7. The method according to claim 6, characterized in that a 10 to 20% aqueous solution of sodium metabisulphite is used. .8th. Process according to Claims 1 to 7, characterized in that the bisulfite ions supplying Substance is used in an amount that contains 4 to 16 equivalents of bisulfite ions per mole of total steroid supplies in the starting mixture. 9. The method according to claim 1 to 8, characterized in that the reaction at a pH between 4 and 8 is carried out. 10. The method according to claim 1 to 9, characterized in that the reaction at increased Temperature, in particular between 40 and 100 ° C. 11. The method according to claim 1, characterized in that that the mixture to be separated is 4-bromo-4,5 a-dihydro-cortisone or a 21-acylate thereof contains. © 909 609/437 8.59 (909 706/340 1.60)