NO833295L - BRASSINOSTEROID DERIVATIVES AND AGENTS FOR PLANT REGULATORY EFFECT ON PLANTS CONTAINING THESE COMPOUNDS - Google Patents

Description

The present invention relates to new brassino-steroid derivatives, method for. production of these compounds as well as agents with growth-regulating action for plants containing these compounds.

From rapeseed pollen, a plant growth-promoting steroid - brassinolide - was isolated and its structure elucidated (p. M.D. Grove et al., Nature Vol. 281, 216 (1979)). However, the growth-regulating effect of this compound is not satisfactory.

The aim of the present invention is to provide new brassinosteroid derivatives which, compared to the known constitutional analogue brassinolide, exhibit superior growth-regulating properties for plants.

According to the invention, this objective is solved with an agent which is characterized by the fact that it contains at least one compound of the general formula

in which R^~j denotes a Cg-C-^<-a>alkyl radical or a Cg-<C>1Q<->alkenyl radical and

Z denotes the group - C - 0 - CH9 - or - 0 - C - CH9 -,

ii ^ ii z 0 0

1*2 and R^ are either different and denote hydrogen or an acyl residue, or together denote the group

or

where X denotes hydrogen,

C₁-C₁-alkyl or C₁-C₁- alkoxy and Y denotes hydrogen, C₁-C₁-alkyl, C₁-C₁-j- alkoxy or aryl.

The new compounds act as geometric isomers, whereby -OR2 and -OR2 are cis 2a,3a or cis 23,33-oriented. The individual isomers and their mixtures fall within the scope of the invention.

The new compounds are excellently suitable for regulating plant growth of various useful plants and surpass in their spectrum of action as well as in their compatibility in a surprising way the previously indicated product with the same direction of action.

The new compounds increase the vegetative growth of useful plants, but in certain concentration ranges can also inhibit this. Furthermore, it is possible to achieve a certain increase due to an impact on the generative phase.

In general, the substances act on the membrane system in useful plants and change its permeability to different substances.

Under certain conditions, they can also provide an anti-stretch effect.

As the new compounds both qualitatively and quantitatively cause changes in the plants as well as changes in the plants' metabolism, they belong to the class of plant growth regulators which exhibit the following application possibilities.

Inhibition of the vegetative growth of woody plants and weeds, for example at roadsides, rail installations and the like, to avoid excessive growth. Growth retardation of cereals to avoid late blight, and of cotton to increase yield.

Effect on the branching of vegetative and generative organs in ornamental and useful plants to increase flower production or in tobacco and tomatoes to inhibit side shoots.

Improving the quality of the fruit, for example an increase in the sugar content of sugar cane, sugar beet or fruit and achieving a simultaneous ripening of the crop leading to a higher yield.

Increasing resistance to stress, such as e.g. to climatic influences such as cold and drought, but also to phytotoxic effects of chemicals.

Influence of latex flow in rubber plants.

Formation of parthenocarpic fruits, pollen sterility and influence of heredity are other application possibilities.

Control of seed germination or bud formation.

Defoliation or adverse effect on fruit drop to

ease the harvest.

The new compounds are particularly suitable for influencing the vegetative and generative growth of certain legumes such as e.g. soy.

Depending on the application target, the application amounts generally amount to 0.001 to 1 kg of active substance/ha, but possibly larger amounts can also be used.

The period of use depends on the purpose of use and the climatic conditions.

Among the new connections that stand out.' themselves by the described effect are particularly those of general formula I in which R,., denotes 2-methyl-heptan-6-yl, 2-methyl-3-ethyl-hept-4-en-6-yl, 2,3- dimethyl-hept-4-en-6-yl, 2-methyl-3-ethyl-heptan-6-yl or 2,3-dimethyl-heptan-6-yl and

Z denotes the group

or R 2 and R 3 are either different and denote hydrogen or a formyl residue, a C 2 -C 7 -alkyl-CO residue, a C 1 -C 4 -alkyl-CO residue or an aryl CO residue or collectively denotes the group or

in which X denotes hydrogen, C 1 -C 4 -alkyl or C 1 -C 4 -alkoxy and Y denotes hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkyl or aryl.

Examples of Cg-C^Q-alkyl and alkenyl residues that can be mentioned are 2-methyl-heptan-6-yl, 2-methyl-3-ethyl-hept-4-en-6-yl, 2,3-dimethyl-hept- 4-en-6-yl, 2-methyl-3-ethyl-heptan-6-yl and 2,3-dimethyl-heptan-6-yl; aryl residues can mean formyl residues,

a<C>2<-C>7-alkyl-CG—residue, a C2-C7-alkoxy-C1-C3-alkyl-CO-residue and an aryl-CO-residue, such as e.g. acetoxy, methoxyacetoxy, ethoxyacetoxy, propionyloxy, butyryloxy, valeryloxy, pentanoyloxy, hexanoyloxy, heptanoyloxy, dimethylacetoxy, diethylacetoxy, benzoyloxy and phenylacetoxy.

For example, C1-C3-alkyl radicals can be mentioned

methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl and chloromethyl; C 1 -C 4 -Alkoxy residues are, for example, methoxy, ethoxy and propoxy; and finally naphthyl, phenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,6-dichlorophenyl, 2,4-dichlorophenyl, 3,4-dichlorophenyl, 2,4,6-tri-chlorophenyl, 4-bromophenyl-2,4-dibromophenyl, 2,6-dibromophenyl, 2,4,6-tribromophenyl,.2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2,4-difluorophenyl, 2-methylphenyl, 3-methylphenyl , 4-methylphenyl, 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 3,4-dioxymethylenephenyl, 2-phenoxyphenyl, 3-phenoxyphenyl, 2-nitrophenyl and 3-nitrophenyl.

The new compounds can either be used alone, in a mixture with each other or with other active substances. Optionally, defoliating agents, leaf protection agents or pesticides can be added depending on the desired purpose.

If an extension of the spectrum of action is taken into account, other biocides can also be added. Suitable as herbicidally active 'mixing partners' are, for example, the active substances indicated in Weed Abstracts, Vol. 31, 1981,

under the title "List of common names and Abbreviations employed for currently used herbicides and plant growth regulators in weed abstracts". In addition, phytotoxic agents cannot be used which with the herbicides and/or growth regulators can give a synergistic increase in effectiveness,

such as, among other things, wetting agents, emulsifiers, solvents and oily additives.

Appropriately, the new active substances or their mixtures are used in the form of preparations such as powders, flow agents, granules, solutions, emulsions or suspensions, with the addition of liquid and/or solid carriers, respectively diluents, and possibly with the addition of wetting agents , binders, emulsifiers and/or dispersing aids.

Suitable liquid carriers are e.g. water, aliphatic

and aromatic hydrocarbons such as benzene, toluene, xylene, cyclohexanone, isophorone, dimethylsulfoxide, dimethylformamide and mineral oil fractions.

Mineral soil such as e.g. clay species, silica gel, talc, kaolin, attapulkus clay, limestone, silicic acid and plant products, such as e.g. flour.

Examples of surfactants include calcium lignin sulfonate, polyoxyethylene alkyl phenol ether, naphthalene sulfonic acids and their salts, phenol sulfonic acids and their salts, formaldehyde condensates, fatty alcohol sulfates as well as substituted benzene sulfonic acids and their salts.

The proportion of the active substance in the different preparations can vary within wide limits. For example, the agent contains 10 to 80% by weight of active ingredient, 90 to 20% by weight of liquid or solid carriers as well as up to 20% by weight of surfactants.

Application of the agent can be carried out in the usual way, for example with water carrying spray quantities of from 100 to 1000 litres/ha. Application of the agent in the so-called low-volume or ultra-low-volume method is also possible, as well as application in the form of so-called microgranules.

For the preparation of the preparations, for example, the following ingredients can be used:

A.<g>spraying powder

a) 80% by weight active substance

15% by weight kaolin

5% by weight surfactant based on the sodium salt of N-methyl-N-oleyl-taurine and the calcium salt of ligninsulfonic acid.

b) 50% by weight active ingredient

40 wt% clay minerals

5% by weight cell pitch

.5% by weight surface-active substance on the basis of fen mixture. of_calcium salts of ligninsulfonic acid with alkylphenol-polyglycol ether.

c) 20% by weight active ingredient

70% by weight clay minerals

5% by weight cell pitch

5% by weight surfactant on the basis of a mixture of calcium salts of ligninsulfonic acid with alkyl-phenol polyglycol ether.

d) 5% by weight active ingredient

80% by weight clay species

10% by weight cell pitch

5% by weight surfactant based on a fatty acid condensation product.

B. Emulsion concentrate

20% by weight active ingredient

40% by weight xylene

35% by weight dimethylsulfoxyd.-

5% by weight of a mixture of nonylphenyl polyethylene or calcium dodecylbenzene sulphonate.

C. Pasta

45% by weight active ingredient

5% by weight sodium aluminum silicate

15% by weight of cetyl polyglycol ether with 8 mol of ethylene oxide

2% by weight spindle oil

10 wt% polyethylene glycol

23 parts water.

The new compounds can, for example, be prepared by compounds of the general formula

reacted by osmium tetroxide-catalyzed hydroxylation with t-butyl hydroperoxide or with N-methyl-morpholine-N-oxide to compounds of general formula or acted upon by silver acetate and iodine in aqueous acetic acid to form compounds of general formula

which is treated with peracids to form the desired process products in which R, -, and R2 have the meanings indicated above.

For the preparation of the compounds of formula I, one starts from sterols such as cholesterin, stigmasterin, brassicasterin or p-sitosterin, and converts these in a manner known per se to A 2-6-ketosteroids of formula II

(In Heiv. 49, 1581 (1966)).

The further reaction to 2a,3a-cis-glycols of formula III takes place according to known methods, namely osmium tetroxide-catalyzed hydroxylation with 80% t-butyl hydroperoxide (K.B. Sharpless JACS 98, 1986 (1976)) or with N-methyl-morpholine -N-oxide (V. van Rheen, Tetrahedron Lett. 1976, 1973).

The 23,3&-cis-glycols or their derivatives of formula IV are obtained via the Prevost reaction with silver acetate and iodine in aqueous acetic acid (49, 1581 (1966)).

Production of the B-ring lactone of formula I takes place by Baeyer-Villiger oxidation with peracids such as trifluoroperacetic acid, permauric acid, permaleic acid, etc. of the 6-keto steroid of formulas III and IV. With compounds with a C22~C23~ double bond in the side chain, this double bond must be protected by bromination before lactonization.

After the Baeyer-Villiger oxidation, the double bond can be regenerated with zinc in acetic acid.

The following examples illustrate the preparation of the new compounds.

Example 1

a) 3.56 g of 24 S ethyl-5a-cholesta-2,22-dien-6-one was dissolved in 60 ml of t-butanol, 4 ml of 20% tetraethylammonium hydroxide solution was added, the mixture was cooled to 0 ° C and 12 ml of 80% t-butyl hydroperoxide and 6 ml were added

of an osraium tetroxide solution (prepared from 250 mg of OsO^, 49.75 ml of t-butanol and 0.25 ml of 80% t-butyl hydroperoxide). The reaction solution was stirred for 6 hours at room temperature, poured into 5% sodium hydrogen sulphite solution and extracted with ethyl acetate. The extract was washed with water, dried over sodium sulfate and evaporated. After recrystallization from methylene chloride-methanol, 2.3 g of 2α,3α-dihydroxy-24-S-ethyl-5α-cholest-22-en-6-one was obtained.

Sm.p. 234.5 - 235.5° C.

b) 2.2 g of 2a,3a-dihydroxy-24-S-ethyl-5a-cholest-22-en-6-one was dissolved in 15 ml of pyridine, 8 ml of acetic anhydride was added

and 220 mg of 4-dimethylaminopyridine and allowed to stand for 17 hours at 20° C. The product was then precipitated in ice water,

separated, washed.and dried.

c) 2.6 g of impure diacetate was dissolved in 30 ml of ether. and 30 ml of glacial acetic acid added with 0.28 ml of bromine and was stirred for 10 minutes at

room temperature. For the work-up, the mixture was diluted with ether, washed neutral with water and evaporated in vacuo. 3.2 g of impure 2a,3a-diacetoxy-22,2-3-dibromo-24-ethyl-5a-cholestan-6-one were obtained.

d) 4.5 ml of 30% hydrogen peroxide was suspended in 28 ml of methylene chloride, was cooled to -10° C and slowly

27.7 ml of trifluoroacetic anhydride were added dropwise so that the temperature did not exceed +10° C. Then

3.2 g of 2a,3a-diacetoxy-22,23-dibromo-24-ethyl-5a-cholestan-6-one dissolved in 25 ml of methylene chloride was added, and the mixture was stirred for 40 minutes at room temperature. The reaction mixture was then diluted with methylene chloride and washed with water, 5% sodium carbonate solution and with water, was dried and evaporated in vacuo. The residue was heated in 100 ml of acetic acid with 5 g of zinc dust for 1 hour on a steam bath. Zinc was filtered off and the mixture was diluted with methylene chloride and washed neutral with water and evaporated. After chromatography on silica gel (gradient-elution-toluene-acetic ester) and crystallization from acetone-hexane, 1.5 g of 2a,3a-diacetoxy-24-ethyl-7-oxa-B-horao-5a-cholest-22-6 was obtained -on, sm.p. 221 - 223°C and 310 mg of ,2a,3a-diacetoxy-24-ethyl-6-oxa-B-homo-5a-cholest-22-en-7-one, m.p. 202 - 204°C.

Example 2

a) To a solution of 2 g of 24-ethyl-5a-cholesta-2,22-dien-6-one in 270 ml of glacial acetic acid and 3.7 ml of water was added 3.2 g

silver acetate and 1.9 g of iodine, and the mixture was heated to 45°C with stirring for 3 hours. After filtering off

the silver salt, washing with chloroform, the filtrate was diluted with chloroform and was washed with water, sodium thiosulfate and water, was dried and evaporated. After crystallization from acetone-hexane, 1.2 g of 23-acetoxy-33-hydroxy-2 4-ethyl-5a-cholest-22-en-6-one was obtained.

Sm.p. 192 - 194° C.

b) After bromination of the A 22 double bond, Baeyer-Villiger oxidation and zinc reduction as described in Example

lc) and ld) the crude product was chromatographed on silica gel.

Using gradient elution with chloroform-acetone, after recrystallization from hexane-ether, 23-acetoxy-33-hydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22- en-6-one, m.p. 151 - 153° C and in 10% yield 23-acetoxy-33_hydroxy-24-ethyl-6-oxa-B-homo-5a-cholest-22-en-7-one, m.p. 175 - 176° C.

Example 3

a) 2.2 g of 23-acetoxy-33-hydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22-en-6-one was added to 50 ml of methanol to a solution of 500 mg potassium hydroxide in 10 ml of methanol, and the mixture was stirred for 30 minutes at room temperature. The mixture was acidified with acetic acid, the product was precipitated in ice water, separated, washed and dried. After crystallization from chloroform-ether, 1.7 g of 23,33-dihydroxy-2 4-ethyl-7-oxa-B-homo-5a-cholest-22-en-6-one was obtained.

Sm.p. 211 - 213° C.

b) 500 mg of .23/33-dihydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22-en-6-one was added in 4 ml of pyridine cooled to -10° C

0.5 ml of acetic anhydride and the mixture was stirred for 3.5 hours at -5 to fl°. After precipitation with ice water, separation of the product, washing and drying, this was recrystallized from acetone-hexane. It was obtained. 410. mg 33-acetoxy-23-hydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22-en-6-one.

Sm.p. 182 - 184° C.

Example 4

1 g of 2α,3α-dihydroxy-7-oxa-B-homo-5α-cholestan-6-one was dissolved in 10 ml of pyridine, cooled to 0° C. and 1 ml of acetic anhydride was added. The mixture was stirred for 5 hours at 0 - 5° C, poured into ice water, the product was separated, washed and dried. After recrystallization from pentane, 950 mg of 2α-acetoxy-3α-hydroxy-7-oxa-B-homo-5α-cholestan-6-one, m.p. 165.5 - 167° C.

Preparation of starting materials:

a) 25 g of 5α-cholest-2-en-6-one was dissolved in 140 ml of tetrahydrofuran, 14 g of N-methylmorpholine-N-oxide, 25 ml

water and 50 ml of t-butanol and, while stirring, a solution of

250 mg osmium tetroxyd in 50 ml tetrahydrofuran. The reaction solution was stirred for 17 hours at room temperature under exclusion of light. The product was then precipitated in 7 liters of ice water to which 50 ml of 2N sulfuric acid and 1 g of sodium sulphide had been added, the product was separated, washed with water, dissolved in chloroform and the solution evaporated in vacuo. The raw product (30 g). was dissolved in 140 ml of pyridine, and after adding 70 ml of acetic anhydride and 3 g of 4-dimethylaminopyridine, the mixture was allowed to stand for 16 hours at room temperature. After water precipitation, separation of the product, washing with water and

drying, this was chromatographed on silica gel. After recrystallization from ethanol, 2a,3a-diacetoxy-5a-cholestan-6-one was obtained in 75% yield, m.p. 150.0 -

151.5° C and in 15% yield 23,3β-diacetoxy-5α-cholestan-6-one, m.p. 183.5 - 185° C. b) 26 ml of 30% hydrogen peroxide was. suspended in methylene chloride, was cooled to -10° C, whereupon 161 ml of trifluoroacetic anhydride was slowly added dropwise, so that the temperature did not exceed +10° C. • Then 2 7.2 g of 2a,3a-diacetoxy-5a-cholestane-6- on in 160 ml of methylene chloride added and the mixture was stirred for 40 minutes at room temperature. For work-up, the reaction mixture was diluted with methylene chloride and washed with water, 5% sodium carbonate solution and with water and was evaporated in vacuo. After chromatography on silica gel and recrystallization from acetone-hexane, 2a,3a-diacetoxy-7-oxa-B-homo-5a-cholestan-6-one was obtained in 81% yield, m.p. 183 - 184° C and in 6.2% yield 2a,3a-diacetoxy-6-oxa-B-homp-5a-cholestan-7-one,

sm.p. 245 - 247° C.

c) 28.3 g of 2a,3a-diacetoxy-7-oxa-B-homo-5a-cholestan-6-one was dissolved in 500 ml of methanol and after the addition of a

solution of 14 g of potassium hydroxide in 150 ml of methanol, the mixture was stirred for 30 minutes at room temperature. The reaction solution was then acidified with acetic acid, precipitated with ice water, the product was separated, washed with water and dried. After recrystallization from acetone-pentane, 22.4 g (95%) of 2a,3a-dihydroxy-7-oxa-B-homo-5a-cholestan-6-one were obtained, m.p. 138 - 140° C.

Example 5

a) 1.1 g of 2a,3a-diacetoxy-6-oxa-B-homo-5a-cholestan-7-oh was saponified as described in Example 4c). It was

obtained 785 mg of 2a,3a-dihydroxy-6-oxa-B-homo-5a-chole-stan-7-one with m.p. 216.5 - 218° C.

b) 250 mg of 2a,3a-dihydroxy-6-oxa-B-homo-5a-cholestan-7-orT was dissolved in 2 ml of pyridine, was cooled to -10° C, was

added 0.24 ml of acetic anhydride and was stirred for 4 hours at

-5 to 0° C. After precipitation with ice water, separation of the product, washing and drying, this was recrystallized

from acetone-hexane. 210 mg of 2a-acetoxy-3a-hydroxy-6-oxa-B-homo-'5a-cholestan-7-one were obtained, m.p. 199 -

201°C.

Example 6

600 mg of 2a,3a-dihydroxy-24-methyl-6-oxa-B-homo-5a-cholest-22-en-7-one was acetylated as described in Example 5 b). 515 mg of 2α-acetoxy-3α-hydroxy-24-methyl-6-oxa-B-homo-5α-cholest-22-en-7-one were obtained, m.p. 173 - 174°C. Preparation of starting materials: 24-methyl-5a-cholesta-2/22^.dien-6-one was prepared from brassicasterin according to known methods, and this was reacted as described in Example 1.

Example 7

1 g of 2(3,3f}-dihydroxy-7-oxa-B-homo-5a-cholestan-6-one was dissolved in 100 ml of acetone and 100 ml of tetrahydrofuran, was cooled to 0° C, was added 0.5 ml boron trifluoride etherate and was stirred for 30 minutes at 0 to 5° C. After addition of 1 ml of pyridine, the mixture was evaporated in vacuo and the product was recrystallized from methylene chloride-isopropyl ether.

731 mg of 23,33-isopropylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one were obtained, m.p. 216 - 217° C.

In an analogous way.was produced:

2a,3a-isopropylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one,

sm.p. 216 - 217° C.

2α,3α-isopropylidenedioxy-2 4-ethyl-7-oxa-B-homo-5α-cholestan-22-en-6-one, m.p. 157 - 158° C.

Example 8

900 mg of 2α,3α-dihydroxy-7-oxa-B-homo-5α-cholestan-6-one was dissolved in 10 ml of pyridine, cooled to 0° C, 1.8 ml of valeric anhydride was added and stirred for 10 hours at 0 to 5° C. After work-up as described in Example 4, 950 mg of 2a-valeryloxy-3a-hydroxy-7-oxa-B-homo-5a-cholestan-6-one, m.p. 92 - 94° C.

Example 9

2α,3α-diacetoxy-24-ethyl-7-oxa-B-homo-5α-cholest-22-en-6-one was saponified as described in Example 3 and was partially acetylated. 2α-acetoxy-3α-hydroxy-24-ethyl-7-oxa-B-homo-5α-cholest-22-en-6-one was obtained in 70% yield, m.p. 158 - 160° C.

Example 10

900 mg of 2α,3α-dihydroxy-7-oxa-B-homo-5α-cholestan-6-one was dissolved in 10 ml of pyridine, cooled to 0° C, 1 ml of ethoxyacetic anhydride was added and stirred for 5 hours at 0 — 5° C. After working up as described in Example 4, after recrystallization from acetone-hexane, 720 mg of 2a-e±hoxyacetoxy-3a-hydroxy-7-oxa-B-homo-5a-cholestan-6-one were obtained , mp 172 - 173° C.

Example 11

300 mg of 2a,3a-dihydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22-en-6-one was stirred in 3 ml of pyridine with 780 mg of phenylacetic anhydride for 10 hours at 0 - 5°C After working up and recrystallization from acetone-hexane, 210 mg of 2a-phenylacetoxy-3a-hydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22-ren-6-one were obtained, m.p. - 185 - 186° C.

Example 12

500 mg of 2a, 3a-dihydroxy-7-oxa-B-homio-5a-cholestan-6-one was added to 50 ml of benzene, 0.75 ml of triethyl orthoacetic acid ester and 5 mg of p-toluenesulfonic acid. The solution was stirred for 20 minutes at room temperature, 3 drops of pyridine were added and evaporated in vacuo. The residue was dissolved in methylene chloride, washed with water, dried over sodium sulfate and evaporated. 605 mg of 2a,3a-(1-ethoxy-ethylenedioxy)-7-oxa-B-homo-5a-cholestan-6-one were obtained, m.p. 150 - 154° C.

In an analogous manner was prepared: 2a,3a-(1-ethoxy-ethylenedioxy)-6-oxa-B-homo-5a-cholestan-7-one

sm.p. 122 - 124° C,

2α,3α-(1-ethoxy-propylidenedioxy)-7-oxa-B-homo-5α-cholestan-6-one, m.p. 115 - 118° C, 22,3a-(1-methoxy-methylenedioxy)-24-ethyl-7-oxa-B-homo-5a-cholest-22-en-6-one, m.p. 123 - 125° C.

Example 13

500 mg of 2a,3a-dihydroxy-7-oxa-B-homo-5a-cholestan-6-one was added to 5 ml of tetrahydrofuran, 1.5 ml of acetophenone and 0.1 ml of boron trifluoride etherate and heated for 3 hours to reflux . Then the solution was evaporated in vacuo, 1 ml of pyridine was added, and the solution was evaporated in high vacuum. After trituration with hexane, it was obtained

465 mg of amorphous 2a,3a-(1-methyl-1-phenyl-methylenedioxy)-7-oxa-B-homo-5a-cholestan-6-one as diastereomeric mixture with melting point 130.5 - 132° C.

Example 14

500 mg of 2a,3a-dihydroxy-7-oxa-B-horao-5a-cholestan-6-one was dissolved in 15 ml of diethyl carbonate, heated to boiling and after distilling off 2 ml of diethyl carbonate, 30 mg of sodium methylate was added. A few ml were distilled from the reaction solution within 3 minutes. After cooling, 0.15 ml of glacial acetic acid was added to the reaction solution and evaporated in vacuo. The residue was recrystallized from acetone-hexane. 450 mg of 2a,3a-carbonyldioxy-7-oxa-B-homo-5a-cholestan-6-one were obtained, m.p. 203.5 - 205° C.

In an analogous manner was prepared: 2a,3a-carbonyldioxy-24-ethyl-7-oxa-B-homo-5a-cholest-22-en-6-one, m.p. 193 - 195° C

23,33-carbonyldioxy-7-oxa-B-homo-5a-cholestan-6-one,

sm.p. 212 - 214° C

Example 15

300 mg of 2a,3a-dihydroxy-7-oxa-B-homo-5a-cholestan-6-one was dissolved in 2 ml of benzaldehyde, 0.02 ml of 70% perchloric acid was added and the mixture was stirred for 2 hours at room temperature. The solution was then neutralized with pyridine, diluted with hexane and chromatographed over silica gel. With hexane-acetic ester (6:4) 258 mg of 2a,3a-benzylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one were eluted, which was recrystallized from ether-pentane. Sm.p. 137 - 139° C.

In an analogous way, the following was produced:

2a,3a-benzylidenedioxy-6-oxa-B-homo-5a-cholestan-7-one,

sm.p. 179 - 180° C,

23/33-benzylidenedioxy-6-oxa-B-homo-5a-cholestan-7-one,

sm.p. 129 - 131° C

23,33-benzylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one-

sm.p. 153 - 155° C

The new compounds are crystalline, colorless and odorless substances that are poorly soluble in water, conditionally soluble in aliphatic hydrocarbons such as petroleum ether, hexane, pentane and cyclohexane, well soluble in halogenated hydrocarbons such as chloroform, methylene chloride, tetrachlorocarbon, aromatic hydrocarbons such as such as benzene, toluene and xylene, ethers such as diethyl ether, tetrahydrofuran and dioxane, carboxylic acid nitriles such as acetonitrile,. ketones such as acetone, alcohols such as methanol and ethanol, carboxylic acid amides such as dimethylformamide and sulfoxides such as dimethylsulfoxyd.

The following examples illustrate the application possibilities for the new compounds, in the form of the previously indicated preparations.

Example 16

Growth of bush beans.

Bush beans of the variety "Pinto" were grown in climate chambers at 25° C and 90% humidity under the influence of light with a high proportion of intensity in the range of 660 nm and a very low proportion in the range of 730 nm.

After 6 days of cultivation, 10 and 20 micrograms of the compounds to be tested were dissolved in the solvent and applied to the developing second internode. 3 days after application, the increase of the internodes was measured and the percentage elongation determined in comparison with the control.

The table contains the results of these experiments.

The results show that the new compounds under the specified test conditions exhibit a more intensive stretch than the comparator and the control.

The comparator further only causes a more or less strong increase in thickness growth, which even partially leads to a compression of the internodes.

Example 17

Stimulation of root growth in mung beans.

Under greenhouse conditions, mung beans were germinated in aqueous emulsions of the compounds to be tested in a concentration of 0.01% by weight.

After 6 days, the root length of the germinated plants was determined.

The table contains the results of these trials in the form of percentages.

Example 18

Increasing the resilience of useful plants.

The useful plants indicated in the table were treated by the pre-emergence method with aqueous emulsions of the compounds to be tested or their mixtures. One week after the treatment, the treatment result was assessed according to a form from 0 to 10, where 0 = 100% destruction and 10 = no damage.

It appears that the new compounds give the plants a higher resistance than the known herbicide.

Claims (8)

1. Brassinosteroid derivatives of general formula in which <R>^7 be denotes a Cg-C^g-alkyl residue or a Cg-C^Q-alkenyl residue and Z denotes the group or R 2 and R 1 are either different and denote hydrogen or an acyl residue, or together denote the group or in which X denotes hydrogen, C-^-C^-alkyl or C-^-C-^-alkoxy and Y denotes hydrogen, C₁ -C₁ -alkyl, C₁ -C₂ -alkyloxy or aryl. 2. Brassinosteroid derivatives according to claim 1, characterized in that R17 is 2-methyl-heptan-6-yl, 2-methyl-3-ethyl-hept-4-en-6-yl, 2,3-dimethyl-hept- 4-en-6-yl, 2-methyl-3-ethyl-heptan-6-yl or 2,3-dimethyl-heptan- S-yl and Z are the group or R2 and R^ are either different and denote hydrogen or a formyl residue, C2~<C>7 -alkyl-CO-residue, C2-C7 -alkyl-C1-C3 -alkyl-CO-residue or an aryl-CO-residue, or together denote the group or where X denotes hydrogen, C 1 -C 4 -alkyl or C 1 -C 1 -alkyl and Y denotes hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy or aryl. 3. Brassinosteroid derivatives according to claim 1, characterized in that these are 2a,3a-diacetoxy-2 4-ethyl-7-oxa-B-homo-5a-cholest-2 2-en-6-one, 2a, 3a- diacetoxy-2 4-ethyl-6-oxa-B-hoino-5a-cholest-22-en-7-one, 23-acetoxy-33-hydroxy-2 4-ethyl-7-oxa-B-homo-5a- cholest-22- one-7-one, 33-acetoxy-33-hydroxy-2 4-ethyl-6-oxa-B-homo-5a-cholest-22- one-7-one, 33-acetoxy-23-hydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22- one-6-one, 2a-acetoxy-3a-hydroxy-7-oxa-B-homo-5a-cholestan-6-one, 2a-acetoxy-3a-hydroxy-6-oxa-B-homo-5a-cholestan-7-one, 2a- acetoxy-3a-hydroxy-24-methyl-6-oxa-B-homo-5a-cholest-22- one-7-one, 23-33-isopropylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one, 2a,3a-isopropylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one, 2a,3a-isopropylidenedioxy- 24-ethyl-7-oxa-3-horno-5a-cholest- 22-a-6-on, 2a-valeryloxy-3a-hydroxy-7-oxa-B-homo-5a-cholestan-6-one, 2a-acetoxy-3a-hydroxy-24-ethyl-7-oxa-B-homo-5a-cholest-22- one-6-one, 2a-ethoxyacetoxy-3a-hydroxy-7-oxa-B-homo-5a-cholestan-6-one, 2a-phenylacetoxy-3a-hydroxy-24-ethyl-7-oxa-B-homo-5a-cholest- 22-a-6-on, 2a,3a-(1-ethoxy-ethylenedioxy)-7-oxa-B-homo-5a-cholestan-6-one, 2a,3a-(1-ethoxy-ethylenedioxy)-6-oxa-B-homo-5a- cholestan-7-one, 2a,3a-(1-ethoxy-propylidenedioxy)-7-oxa-B-homo-5a-cholestan- 2-on, 2a,3a-(1-methoxy-methylenedioxy)-24-ethyl-7-oxa-B-homo-5a- cholest-22-en-6-on, 23,23-(1-ethoxy-ethylenedioxy)-24-ethyl-7-oxa-B-homo-5a- cholest-22-en-6-on, 2a,3a-(1-methyl-1-phenyl-methylenedioxy)-7-oxa-B-homo-5a- cholestane-6-one, -2a,3a-carbonyldioxy-7-oxa-B-homo-5a-cholestan-6-one, 2a,3a-carbonyldioxy-24-ethyl-7-oxa-B-homo-5a-cholest-22-en-6 -on, 23r 33-carbonyldioxy-7-oxa-B-horao-5a-cholestan-6-one, 2a,3a-benzylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one, 2a,3a-benzylidenedioxy-6 -oxa-B-homo-5a-cholestan-7-one, 23/3 3-benzylidenedioxy-6-oxa-B-homo-5 a-chole s tan-7-one, 23,33-benzylidenedioxy-7-oxa-B-homo-5a-cholestan-6-one. 4. Process for the production of brassinosteroid derivatives according to claims 1-3, characterized in that compounds of general formula. is reacted by osmium tetroxide-catalyzed hydroxylation with t-butyl hydroperoxide or with N-methyl-morpholine-N-oxide to compounds of the general formula or reacted with silver acetate and iodine in aqueous acetic acid to form compounds of general formula which are treated with peracids to form the desired process products in which R. and R.sub.2 have the meanings given above. 5. Agent with growth-regulating effect for plants, characterized in that they contain at least one compound according to claims 1-3. 6. Agent with growth-regulating effect for plants according to claim 5, in a mixture with carrier and/or auxiliary substances. 7. Means according to claims 5 and 6 for influencing the vegetative and generative growth of legumes, in particular soya. 8. Agent with growth-regulating effect for plants according to claim 5, produced by the method according to claim 4.