GB2127022A

GB2127022A - 28-Methyl-brassinosteroid derivatives having a plant growth- regulating action and their manufacture and use

Info

Publication number: GB2127022A
Application number: GB08324348A
Authority: GB
Inventors: Ulrich Kerb; Ulrich Eder; Hansjorg Krahmer
Original assignee: Schering AG
Current assignee: Bayer Pharma AG
Priority date: 1982-09-15
Filing date: 1983-09-12
Publication date: 1984-04-04
Also published as: GB8324348D0; PL136535B1; PT77259B; CH655730A5; FR2532942B1; DK420383A; JPS5955880A; GR78758B; KR840005737A; AU1865583A; RO88035B; DE3234606A1; YU169783A; IT8322439A0; ZA836870B; BE897759A; IL69700A0; JPS627195B2; LU85001A1; DK420383D0

Abstract

Novel 28-methyl-brassinosteroid derivatives of the general formula I <IMAGE> (in which Z represents -CO-O- CH2- or -O-CO-CH2-, and the 3 symbols R2, R3 and R22 each represents H or acyl, at least 1 of these 3 symbols representing acyl, or R22 represents H or acyl and R2 and R3 together represent <IMAGE> X representing H, optionally chlorinated C1-C4-alkyl or C1-C3- alkoxy and Y representing H, optionally chlorinated C1-C4-alkyl, C1-C3-alkoxy or optionally substituted aryl) and their manufacture. The novel compounds have a plant growth-regulating action, being particularly suitable for influencing the vegetative and generative growth of leguminous plants, for example soya bean plants, and accordingly may be made up with suitable carriers and/or auxiliaries into plant growth- regulating preparations and may be used for treating seeds, living plants and areas of land.

Description

SPECIFICATION 28-Methyl-brassinosteroid derivatives having a plant growth-regulating action and their manufacture and use The present invention is concerned with novel 28-methyl-brassinosteroid derivatives, with processes for the manufacture of these compounds and with their use as agents having a growthregulatory effect on plants.

A steroid that promotes plant growth, namely brassinolide, has been isolated from the pollen of rape and its structure determined [see M.D. Grove et al., Nature, vol. 281, 21 6 (1979)]; it is (22R,2 3R,24S)-2a,3 o',2 2,2 3-tetrahydroxy-2 4-methyl-6,7-s-5a-cholesta no-6,7-lactone. The growthregulatory action of this compound is, however, not satisfactory.

The problem upon which the present invention is based has been to develop novel brassinosteroid derivatives that, in comparison with the known brassinolide of analogous constitution, have superior growth-regulatory properties for plants.

This problem is solved according to the present invention by the novel 28-methyl-brassinosteroid derivatives, as defined below.

The present invention accordingly provides compounds of the general formula I

in which Z represents a group of the formula

and R2, R3 and R22 each represents a hydrogen atom or an acyl group, with the proviso that at least one of the symbols R2, R3 and R22 represents an acyl group, or R22 represents a hydrogen atom or an acyl group and R2 and R3 together represent a group of the formula

in which X represents a hydrogen atom, a C,-C4-alkyl group, a chlorinated C1-C4-alkyl group or a C1-C3alkoxy group and Y represents a hydrogen atom, a Ct-C4-alkyl group, a chlorinated C1-C4-alkyl group, a C1-C3alkoxy group or an unsubstituted or substituted aryl group.

The compounds of the present invention occurs as geometricai isomers, -OR2 and -OR3 being cis 2a,3a or cis 2p,3p oriented and -OR22 and -OH23 having the cis 22R,23R configuration or the cis 22S,23S configuration. Thus it is to be understood in the description and claims herein that when reference is made to a compound of the general formula I, such a compound may be in the form of such an individual isomer or of a mixture of two or more such isomers.

The compounds of the present invention are outstandingly suitable for regulating plant growth in various crop plants and are surprisingly superior in their range of action and also in their compatibility as compared with the product of the same direction of action, mentioned in the introduction above.

The compounds according to the present invention are capable of promoting the vegetative growth of crop plants and, in certain concentration ranges, also of inhibiting it. In addition, it is possible, by influencing the generative phase, to achieve certain multiple harvests.

In general, the compounds of the present invention act on the membrane system in crop plants and alter the permeability thereof to various substances.

Under certain conditions, they may exhibit an anti-stress action.

Since the compounds according to the present invention bring about both qualitative and quantitative changes in plants and also alter the metabolism of the plants, they are to be included in the class of plant growth regulators which are distinguished by the following possible applications: Inhibiting the vegetative growth in woody and herbaceous plants, for example inter alia on roadsides and railway tracks, in order to suppress a growth that is too lush. Inhibiting growth in cereals in order to prevent lodging or snapping off, and in cotton to increase the yield.

Infiuencing the branching out of vegetative and generative organs in ornamental and crop plants in order to increase the amount of blossom, or in the case of tobacco and tomato plants to inhibit the formation of side shoots.

Improving the quality of the fruit, for example increasing the sugar content of sugar cane, sugar beet or fruit, and producing a more uniform ripening of the crop which results in higher yields.

Increasing the resistance to stress, for example to climatic effects, for example cold and drought, and also to the phytotoxic effects of chemicals.

Influencing the flow of latex in rubber plants.

The development of parthenocarpic fruits, pollen sterility and influencing of sex are likewise possible applications.

Controlling the germination of seeds or the production of buds.

Defoliating or influencing the fall of fruit to facilitate harvesting.

The compounds according to the present invention are particularly suitable for influencing the vegetative and generative growth in some leguminous plants, for example soya bean plants.

Depending on the purpose of application, the quantities applied are generally within the range of from 0.001 to 1 kg of active substance per hectare, but greater application quantities may also be used if appropriate. When two or more compounds of the present invention are used, the range of 0.001 to 1 kg per hectare refers of course to the total application quantities.

The time of application depends on the purpose of application and on the climatic conditions.

When used as agents for regulating the growth of plants, the compounds of the present invention may, if desired, be used in admixture with a suitable carrier and/or an auxiliary.

Of the compounds according to the present invention, those that are especialiy distinguished by the described action are the compounds of the general formula I in which Z represents a group of the formula

and R2, R3 and R22 each represents a hydrogen atom or an acyl group selected from formyl groups, C2 C7-alkyl-CO- groups, C2-C7-alkoxy-C,-C3-alkyl-CO- groups, aryl-CO- groups and aryl-C,-C2-alkyl-CO- groups, with the proviso that at least one of the symbols R2, R3 and R22 represents such an acyl group, or, R22 represents a hydrogen atom or such an acyl group and R2 and R3 together represent a group of the formula

in which X represents a hydrogen atom, a C,-C4-alkyl group, a chlorinated C,-C4-alkyl group or a C,-C3alkoxy group and Y represents a hydrogen atom, a C,-C4-alkyl group, a chlorinated C,-C4-alkyl group, a C,-C3alkoxy group or an unsubstituted or substituted aryl group.

As acyl groups represented by each of the symbols R2, R3 and R22 in the general formula I there may be mentioned, for example, a formyl group, a C2-C7-alkyl-CO- group, a C2-C7-alkoxy-C,-C3-alkyl- CO- group, an aryl-CO- group and an aryl-C,-C2-alkyl-CO- group, for example acetyl, methoxyacetyl, ethoxyacetyl, propionyl, butyryl, valeryl, pentanoyl, hexanoyl, heptanoyl, dimethylacetyl, diethylacetyl, benzoyl and phenylacetyl.

As optionally chlorinated C,-C4-alkyl groups represented by the symbols X and Y there may be mentioned, for example, methyl, ethyl, propyl, isopropyl, butyl, sec.-butyl, tert.-butyl and chloromethyl; as C,-C3-alkoxy groups there may be mentioned, for example, methoxy, ethoxy and propoxy; as optionally substituted aryl groups there may be mentioned, for example, naphthyl, phenyl, 2chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 2,6-dichlorophenyl, 2,4-dichlorophenyl, 3,4dichlorophenyl, 2,4,6-trichlorophenyl, 4-bromophenyl, 2,4-dibromophenyl, 2,6-dibromophenyl, 2,4,6tribromophenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2,4-difluorophenyl, 2-methylphenyl, 3methylphenyl, 4-methylphenyl, 3,4-dimethylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4methoxyphenyl, 3,4-dioxymethylenephenyl, 2-phenoxyphenyi, 3-phenoxyphenyl, 2-nitrophenyl and 3nitrophenyl.

The present invention accordingly also provides a preparation for regulating the growth of plants, which comprises at least one compound of the general formula I in admixture with an auxiliary.

The present invention further provides a preparation for regulating the growth of plants, which comprises at least one compound of the general formula I in admixture or conjunction with a suitable carrier.

The present invention further provides a method of regulating the growth of a living plant, wherein the living plant and/or the area in the vicinity of the living plant is/are treated with a compound of the general formula I.

The present invention further provides a method of regulating the growth of plants in an area of land, for example a crop area, wherein the area is treated with a compound of the general formula I.

The present invention further provides a method of dressing seeds, wherein the seeds are treated with a compound of the general formula I.

The present invention further provides a pack which comprises at least one compound of the general formula I, together with instructions for its use for regulating the growth of living plants.

The compounds according to the present invention may be applied singly or in the form of mixtures with each other or with other active substances. If desired, defoiiants, plant-protecting agents and/or pesticides may be added, depending on the desired aim of application.

If a broadening of the range of action is intended, other biocides also may be added. For example, as herbicidally active co-components there are suitable the active substances that are listed in Weed Abstracts, vol. 31, 1981 under the titie "List of common names and Abbreviations employed for currently used herbicides and plant growth regulators in weed abstracts". In addition, it is also possible to use non-phytotoxic agents that are capable of producing with herbicides and/or growth regulators a synergistic increase in action, inter alia, for example, wetting agents, emulsifiers, solvents and oily additives.

The active compounds according to the present invention or mixtures thereof are advantageously applied in the form of preparations, for example powders strewable preparations, granules, solutions, emulsions or suspensions, with the addition of liquid and/or solid vehicles or diluents and, if desired, of surface-active agents, for example wetting agents, adhesion-promoting agents, emulsifiers and/or dispersing agents.

Suitable liquid carriers are, for example, water, aliphatic and aromatic hydrocarbons, for example benzene, toluene and xylene, cyclohexanone, isophorone, dimethyl sulphoxide and dimethylformamide, and also mineral oil fractions.

As solid carriers there are suitable, for example, mineral earths, for example Tonsil, silica gel, talc, kaolin, attaclay, limestone and silicic acid, and vegetable products, for example meals.

As surface-active agents there may be mentioned, for example, calcium lignin-sulphonate, polyoxyethyiene-alkylphenol ethers, naphthalenesulphonic acids and salts thereof, phenolsulphonic acids and salts thereof, formaldehyde condensates, fatty alcohol sulphates and also substituted benzenesulphonic acids and salts thereof.

The total amount of the active substance(s) in the various preparations may vary within wide limits. For example, the preparations may contain approximately from 10 to 80% by weight of active substance(s), approximately from 90 to 20% by weight of liquid or solid carrier and also, if desired, up to 20% by weight of surface-active agent(s).

The active substances may be applied in the customary manner, for example with water as the carrier in spray liquor quantities of approximately from 1 00 to 1 000 litres per hectare. It is also possible to apply the active substances by the so-called low-volume- or ultra-low-volume-method and it is furthermore possible to apply them in the form of so-called microgranules.

The following components, for example, are used for the manufacture of the preparations: Table I A. Sprayable powder a) 80% by weight of active substance 15% by weight of kaolin 5% by weight of surface-active agents based on the sodium salt of N-methyl-N-oleyl-taurine and the calcium salt of ligninsulphonic acid.

b) 50% by weight of active substance 40% by weight of clay minerals 5% by weight of cellulose pitch 5% by weight of surface-active agents based on a mixture of the calcium salt of ligninsulphonic acid and alkylphenol-polyglycol ethers.

c) 20% by weight of active substance 70% by weight of clay minerals 5% by weight of cellulose pitch 5% by weight of surface-active agents based on a mixture of the calcium salt of ligninsulphonic acid and alkylphenol-polyglycol ethers.

d) 5% by weight of active substance 80% by weight of Tonsil 10% by weight of cellulose pitch 5% by weight of surface-active agents based on a fatty acid condensation product.

B. Emulsion concentrate 20% by weight of active substance 40% by weight of xylene 35% by weight of dimethyl sulphoxide 5% by weight of a mixture of nonylphenyl-polyoxyethylene and calcium dodecyl-benzene sulphonate.

C. Paste 45% by weight of active substance 5% by weight of sodium aluminium silicate 15% by weight of cetylpolyglycol ether with 8 moles of ethylene oxide 2% by weight of spindel oil 10% by weight of polyethylene glycol 23 parts of water.

The novel compounds of the present invention may be manufactured, for example, from compounds of the general formula II

in which Z has the meaning given above.

Thus, for example, compounds of the general formula I in which R2, R3 and R22 each represents a hydrogen atom or an acyl group, at least one of these symbols representing an acyl group, may be prepared by reacting a compound of the general formula II with a carboxylic acid anhydride, if desired in the presence of a catalyst.

Compounds of the general formula I in which R22 represents a hydrogen atom or an acyl group and R2 and R3 together represent a group of the formula

X and Y having meanings given above, may be prepared, for example, by reacting a compound of the general formula Ila

in which Z has the meaning given above and R221 represents a hydrogen atom or an acyl group, with a) boron trifluoride etherate, if desired dissolved in an organic solvent, b) orthoacetic acid triethyl ester, if desired in the presence of a catalyst, dissolved in an organic solvent, c) acetophenone in perchloric acid, or d) diethyl carbonate and a catalytic amount of sodium methoxide.

The desired process products may be isolated in a manner known per se.

The starting materiais, 28-methyl-brassinolides or derivatives thereof, are manufactured from stig-masterin, for example as described in Steroids 39, 89 (1982).

The following Examples illustrate the invention. These examples illustrate the manufacture of the compounds of the present invention.

Example 1 1 g of 2α,3α,22S,23S-tetrahydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one was dissolved in 10 ml of pyridine, the solution was cooled to OOC, 0.5 ml of acetic anhydride was added and the whole was stirred for 5.5 hours at --5 to OOC. The whole was then precipitated in ice-water and the product was suction-filtered, washed with water, dried and chromatographed over silica gel. After recrystallisation from acetone/hexa ne, 81 0 mg of 2a-acetoxy-3 a,22S,2 3S-trihydroxy-24-ethyl-7-oxa- B-homo-5a-cholestan-6-one, m.p. 1 250C, were obtained.

Example 2 1 g of 2α,3α,22S,23S-tetrahydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one was dissolved in 10 ml of pyridine, the solution was cooled to 0 C, 1 ml of acetic anhydride was added and the whole was stirred for 7 hours at OOC. The whole was then precipitated in ice-water and the product was suction-filtered, washed with water and dried. After chromatography over silica gel (gradient elution with chloroform/acetone), 320 mg of 2a,3a-diacetoxy-2 2S,23S-dihydroxy-24-ethyl-7-oxa-B-homo- 5a-cholestan-6-one, m.p. 1200 C, and 535 mg of 2a,22S-diacetoxy-3a,23S-dihydrnxy-24-ethyl-7- oxa-B-homo-5a-cholestan-6-one, m.p. 1460 C, were obtained.

Example 3 210 mg of 2a,3,22R,23R-tetrahydroxy-24-ethyl-7-oxa-B-homo-5(x-cholestan-6-one were reacted as described in Example 1. After recrystallisation from acetone/hexane, 1 70 mg of 2cg-acetoxy- 3 a,22R,23R-trihydroxy-24-ethyl-7-oxa-B-homo-5-cholesta n-6-one, m.p. 246-248 C, were obtained, Example 4 500 mg of 2α,3α,22S,23S-tetra,hydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one were reacted in a manner analogous to that described in Example 1. After recrystallisation from methylene chloride/isopropyl ether, 385 mg of 2α-acetoxy-3α-22S,23S-trihydroxy-24-ethyl-6-oxa-B-homo-5α- cholestan-7-one, m.p. 198-200 C, were obtained.

Example 5 1 g of 2α,3α,22S,23S-tetrahydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one was reacted and separated as described in Example 2. 290 mg of 2α,3α-diacetoxy-22S,23S-dihydroxy-24-ethyl-6- oxa-B-homo-5a-cholestan-7-one, m.p. 1 350C, and 560 mg of 2α,23S-dihydroxy- 24-ethyl-6-oxa-B-homo-5a-cholestan-7-one, m.p. 1 520C, were obtained.

Example 6 500 mg of 2ss,3ss,22S,23S-tetrahydroxy-24-ethyl-7-oxa-B-homo-5α-.cholestan-6-one (m.p.

182-1 830C) were acetylated as described in Example 1. There were thus obtained 410 mg of 3ss acetoxy-2ss,22S,23S-trihydroxy-24-ethyl--7-oxa-B-homo-5α-cholestan-6-one, m.p. 16-162 C.

Example 7 300 mg of 2α,3α,22S,23S-tetrahydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one were dissolved in 3 ml of pyridine, the solution was cooled to OOC and 0.6 ml of valeric anhydride was added. The whole was stirred for 10 hours at 0 C and precipitated in ice-water, and the precipitate was washed with water and dried. The crude product was chromatographed over silica gel and the resulting 2 a-valeryloxy-3 α,22S,23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one n-6-one was recrystallised from acetone/hexane; 0 C.

The following were manufactured in an analogous manner: 2α-heptanoyloxy-3α,22S23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one, m.p.

85-870C, 2a-dimethylacetoxy-3 α,22S,23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholesta n-6-one, m.p.

121-1 22.50C, 2o-butyryloxy-3 α,22S,23S-trihydroxy-24-ethyl-6-oxa-B-homo-5α-cholesta n-7-one, m.p. 92- 940C, and 2a-diethylacetoxy-3 α,22S,23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one, m p.

113-1150C.

Example 8 300 mg of 2α,3α,22S,23S-tetrahydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one were dissolved in 3 ml of pyridine, the solution was cooled to OOC and 1 ml of valeric anhydride was added.

The whole was stirred for 20 hours at OOC and precipitated in ice-water, and the precipitate was washed with water and dried. After chromatography over silica gel (gradient elution with chloroform/acetone), 120 mg of 2,3-divaieryloxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5a- cholestan-6-one, m.p. 109-111 C, and 1 60 mg of 2α,22S-divaleryloxy-3α,23S-dihydroxy-24-ethyl- 7-oxa-B-homo-5α-cholestan-6-one, m.p. 128.5-130 C, were obtained.

The following were manufactured in an analogous manner: 2α,3α-dihexanoyloxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-6-one, m.p.

88-9O0C, and 2α,22S-dihexanoyloxy-3α,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one, m.p.

117-120 C.

Example 9 500 mg of 2α,3α,22R,23R-tetrahydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one were dissolved in 5 ml of pyridine, the solution was cooled to 0 C, 0.3 ml of ethoxyacetic anhydride was added and the whole was stirred for 6 hours at -5 to OOC. After working up and isolating as described in Example 1, 310 mg of 2-ethoxyacetoxy-3,22R,23R-trihydroxy-24-ethyl-7-oxa-B-homo-5- cholestan-6-one, m.p. 182-1 850C, were obtained.

Example 10 0.5 ml of boron trifluoride etherate was added to 1 g of 2α,3α22S,23S-tetrahydroxy-24--ethyl- 7-oxa-B-homo-5a-cholestan-6-one in 1 00 ml of tetrahydrofuran and 1 00 ml of acetone, and the whole was stirred at -5 to OOC for 30 minutes. After the addition of 1 ml of pyridine, the whole was concentrated in vacuo and precipitated with water, and the product was suction-filtered and washed with water. After recrystallisation from acetone, 731 mg of 2α,3α-isopropylidenedioxy-22S,23S- dihydroxy-24-ethyl-7-oxa-B-homo-5cr-cholestan-6-one, m.p. 198-201 C, were obtained.

The following were manufactured in an analogous manner: 2α,3α-isopropylidenedioxy-22S,23S-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one, m.p. 21 1-2130C, and 2ss,3ss-isopropylidenedioxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one, m.p. 189-1910C.

Example 11 1.5 ml of orthoacetic acid triethyl ester and 5 mg of p-toluenesulphonic acid were added to 1 g of 2 a,3 a,22S,23S-tetra hydroxy-24-ethyl-7-oxa-B-homo-5a-cholesta n-6-one in 1 00 ml of benzene and the whole was stirred for 30 minutes at room temperature. After the addition of 2 drops of pyridine, the whole was concentrated in vacuo, diluted with methylene chloride, washed with water and concentrated by evaporation. The crude product was triturated with isopropyl ether and 720 mg of amorphous 2a,3 of( 1 -ethoxy-ethylidenedioxy)-22S,23S-di hydroxy-24-ethyl-7-oxa-B-homo-5a- cholestan-6-one were obtained as a diastereoisomeric mixture.

The following were manufactured in an analogous manner: 2cue,3 an( 1 -ethoxy-propylidenedioxy)-22S,2 3S-dihydroxy-24-ethyl-7-oxa-B-homo-5a-chol estan 6-one (using orthopropionic acid triethyl ester instead of orthoacetic acid triethyl ester), amorphous, 2 a,3 a-( 1 -methoxy-methylenedioxy)-22R,23R-dihydroxy-24-ethyl-7-oxa-B-homo-5a-cholestan- 6-one (using orthoformic acid trimethyl ester instead of orthoacetic acid triethyl ester), m.p.

96-990C, and 2P.3P-( 1 -ethoxy-ethylidenedioxy)-22S,23S-dihyd roxy-24-ethyl-7-oxa-B-homo-5a-cholestan-6- one, m.p. 84-870C.

Example 12 0.01 ml of 72% perchloric acid was added to 200 mg of 2a,3a,22S,23S-tetrahydroxy-24-ethyl- 7-oxa-B-homo-5a-cholestan-6-one in 2 ml of acetophenone and the whole was stirred for 1 6 hours at room temperature. 0.1 ml of pyridine was then added and the whole was chromatographed over silica gel. By gradient elution with toluene/ethyl acetate, 120 mg of amorphous 2a,3a-(1 -methyl-1 -phenyl methylenedioxy)-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5a-cholestan-6-one were obtained as a diastereoisomeric mixture.

The following was manufactured in an analogous manner: 2a,3 a-( 1-methyl- 1 -ph enyl-me thylenedioxy)-22S,23S-dihydrnxy-24-ethyl-6-oxa-8-homo-5a- cholestan-7-one.

Example 13 200 mg of 2α,3α,22S,23S-tetrahydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one in 7 ml of diethyl carbonate and 2 ml of tetrahydrofuran were heated, after the addition of 15 mg of sodium methoxide, for 2.5 hours at 1 3O0C (bath temperature). After cooling, the whole was neutralised with acetic acid and concentrated by evaporation in vacuo. The residue was dissolved in chloroform/acetone and filtered over silica gel, and the filtrate was concentrated. By recrystallisation from acetone/hexane, 1 55 mg of 2 a,3 a-ca rbonyldioxy-22S,2 3S-dihydroxy-24-ethyl-6-oxa-B-homo-5 a-cholesta n-7-one, m.p. 242.5-244 C, were obtained.

The following was manufactured in an analogous manner: 2α,3α-carbonyldioxy-22R,23R-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one, m.p.

21 6-2170C.

Example 14 200 mg of 2α,3α,22S23S-tetrahydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one were dissolved in 4 ml of tetrahydrofuran, 1 ml of benzaldehyde was added, the whole was cooled to -1 50C and 0.2 ml of a perchloric acid solution (prepared from 0.5 ml of 70% perchloric acid in 1.5 ml of tetrahydrofuran) was added. The whole was stirred for 15 minutes at -1 50C, neutralised with pyridine, diluted with chloroform and chromatographed over silica gel. Using chloroform/acetone (1:1) there were eluted 1 53 mg of amorphous 2cg,3-benzylidenedioxy-22S,23S-dihydroxy-24-ethyl-6-oxa-B- homo-5a-cholestan-7-one.

The following were manufactured in an analogous manner: 2α,3α-benzyldenedioxy-22R,23R-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one, and 2α,3α-benzyldenedioxy-22R,23R-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one The compounds according to the present invention are, in general, crystalline colourless and odourless substances that are sparingly soluble in water, soluble to a certain extent in aliphatic hydrocarbons, for example petroleum ether, hexane, pentane and cyclohexane, and readily soluble in halogenated hydrocarbons, for example chloroform, methylene chloride and carbon tetrachloride, aromatic hydrocarbons, for example benzene, toluene and xylene, ethers, for example diethyl ether, tetrahydrofuran and dioxan, carboxylic acid nitriles, for example acetonitrile, ketones, for example acetone, alcohols, for example methanol and ethanol, carboxylic acid amides, for example dimethylformamide, and sulphoxides, for example dimethyl sulphoxide.

The following Examples also illustrate the invention. These Examples illustrate the possible applications for the compounds of the present invention, in the form of preparations as indicated above.

Example 15 Promotion of growth in French beans In a series of tests French beans of a variety "Pinto" were cultivated in a climatic chamber at 250C and 90% atmospheric humidity under the effect of light having a high proportion of intensity in the region of 660 nm and a very low proportion in the region of 730 nm.

After 6 days' cultivation, 1 0 and 50 g, respectively, of the compounds to be tested listed in the Table below were dissolved in solvents and applied to the developing second internodium.

3 days after the application, the extension of the internodia was measured and the percentage increase in length in comparison with a control was determined.

The results of this series of tests are given in the following Table.

Percentage promotion Compounds of the invention 10 yg 50 Hg Acetoxy-3α,22S,23S-trihydroxy- 285 209 24-ethyl-B-homo-7-oxa-5a- cholestan-6-one 2 a-Acetoxy-3 a,2 2R,2 3R-tri hyd roxy- 380 304 24-ethyl-7-oxa-B-homo-5L- cholestan-6-one 2a,22S-Diacetoxy-3a,23S-dihydroxy- 114 215 24-ethyl-7-oxa-B-homo-5a- cholestan-6-one 2α,3α-Diacetoxy-22S,23S-dihydroxy- 323 279 24-ethyl-7-oxa-8-homo-5a- cholestan-6-one 2α-Valeryloxy-3α;,22S,23S-tri- 57 323 hydroxy-24-ethyl-7-oxa-B-homo 5-cholestan-6-one Agents for comparison 2a,3a,22S,23S-Tetrahydroxy-24- 89 114 ethyl-B-homo-7-oxa-5a-cholestan- 6-one 4-(3-lndolyl)-butyric acid 51 38 Control 100 100 The results show that, under the stated test conditions, the compounds according to the present invention brought about a more intense extension than did the agents used for comparison and the control.

In contrast, the agents used for comparison brought about only a more or less marked promotion of the growth in thickness which, in some cases, even led to a compression of the internodia.

Example 16 Growth inhibition in cucumbers In a series of tests cucumber seeds were germinated under greenhouse conditions in aqueous emulsions of the compounds to be tested listed in the Table below in a concentration of 0.01% by weight.

After 6 days, the length of the seed roots and of the shoots was measured.

The following Table shows the percentage inhibition of growth in the stated concentration range.

Percentage growth inhibition Compounds of the invention root shoot 2Acetoxy-3 a,22S,23S-trihydroxy- 38 28 24-ethyl-B-homo-7-oxa-5a- cholestan-6-one 2-Acetoxy-3cg,22R,23R-trihydroxy- 50 28 24-ethyl-7-oxa-B-homo-5a cholestan-6-one 2 -22S-Diacetoxy-3 a,2 3S-dihydroxy- 63 0 24-ethyl-7-oxa-B-homo-5a- cholestan-6-one Percentage growth inhibition Compounds of the invention root shoot 2,3a-Diacetoxy-22S,23S-dihydroxy- 100 56 24-ethyl-7-oxa-B-homo-5a- cholestan-6-one 2a-Valeryloxy-3a,22S,23S-trihydroxy- 75 56 24-ethyl-7-oxa-B-homo-5a- cholestan-6-one Control 100 100 The results show that the compounds according to the present invention have a distinct growth inhibiting action in the test procedure described.

Claims

1. A 28-methyl-brassinolide derivative of the general formula I

in which Z represents a group of the formula

and R2,R3 and R22 each represents a hydrogen atom or an acyl group, with the proviso that at least one of the symbols R2, R3 and R22 represents an acyl group, or R22 represents a hydrogen atom or an acyl group and R2 and R3 together represent a group of the formula

in which X represents a hydrogen atom, a C1-C4-alkyl group, a chlorinated C,-C4-aíkyl group or a C,-C3alkoxy group and Y represents a hydrogen atom, a C,-C4-alkyl group, a chlorinated C,-C4-alkyl group, a C,-C3alkoxy group or an unsubstituted or substituted aryl group.

2. A compound as claimed in claim 1, wherein Z represents a group of the formula

and R2,R3 and R22 each represents a hydrogen atom or an acyl group selected from formyl groups, C2 C7-alkyl-CO- groups, C2-C7-alkoxy-C,-C3-alkyl-CO- groups, aryl-CO- groups and aryl-C,-C,-alkyl-CO- groups, with the proviso that at least one of the symbols R2, R3 and R22 represents such an acyl group, or R22 represents a hydrogen atom or such an acyl group and R2 and R3 together represent a group of the formula

in which X represents a hydrogen atom, a C,-C4-alkyl group, a chlorinated C,-C4-alkyl group or a C-C3- alkoxy group and Y represents a hydrogen atom, a C1-C4-alkyl group, a chlorinated C,-C4-alkyí group, a C,-C3alkoxy group or an unsubstituted or substituted aryl group.

3. 2α-Acetoxy-3α,22S,23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

4. 2α,22S-Diacetoxy-3α,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5alpha;-cholestan-6-one.

5. 2α-Acetoxy-3α,22R,23R-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

6. 2α-Acetoxy-3α,22S,23S-trihydroxy-24-ethyl-6-oxa B-homo-5α-cholestan-7-one.

7-2α,22S-Diacetoxy-3alpha;23S-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one.

8. 3α-Acetoxy-2#,22S,23S-trihydroxy-24-ethyl-oxa-B-homo-5α-cholestan-6-one.

9. 2α-Valeryloxy-3α,22S,23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

10. 2α-Heptanoyloxy-3α,22R,23R-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

11. 2α-Dimethylacetoxy-3α,22S,23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

12.2α-Butyryloxy-3α,22S,23S-trihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one.

13. 2α-Diethylacetoxy-3α,22S,23S-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

14. 2a,3a-Diva leryíoxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5a-choíestan-6-one.

15. 2α,22S-Divaleryloxy-3α,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

16. 2α-Ethoxyacetoxy-3α,22R,23R-trihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

17. 2α,3α-Isopropylidenedioxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6- one.

18. 2α,3α-Isopropylidenedioxy-22S,23S-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7- one.

19. 2#,3#-Isopropylidenedioxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

20. 2α,3α-(1-Ethoxy-ethylidenedioxy)-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α- cholestan-6-one.

21. 2α,3α-(1-Ethoxy-propylidenedioxy)-22S,23S-24-ethyl-7-oxa-B-homo-5α- cholestan-6-one.

22. 2 ,3 an( 1 -Methoxy-methylenedioxy)-22R,23R-dihydroxy-24-ethyl-7-oxa-B-homo-5α- cholestan-6-one.

23. 2#,3#-(1-Ethoxy-ethylidenedioxy)-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α- cholestan-6-one.

24. 2 a,3a-( 1-Methyl- 1 -phenyl-methylenedioxy)-22S,23S-di hydroxy-24-ethyl-7-oxa-B-homo5a-cholestan-6-one.

25. 2 a,3 a-( 1 -Methyl- 1 -phenyl-methyle nedioxy)-22S,23S-di hydroxy-24-ethyl-6-oxa-B-homo- 5a-choiestan-7-one.

26. 2α,3α-Carbonyldioxy-22S,23S-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one.

27. 2α,3α-Carbonyldiocy-22R,23R-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one.

28. 2α,3α-Benzylidenedioxy-22S,23S-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-7-one.

29. 2α,3α-Benzylidenedioxy-22R,23R-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

30. 2α,3α-Benzylidenedioxy-22R,23R-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

31. 2α,3α-Dihexanoyloxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

32. 2a,22S-Dihexanoyloxy-3a,23S-di hyd roxy-24-ethyl-7-oxa-B-homo-5a-cholesta n-6-one.

33. 2α,3α-Diacetoxy-22S,23S-dihydroxy-24-ethyl-7-oxa-B-homo-5α-cholestan-6-one.

34. 2α,3α-Diacetoxy-22S,23S-dihydroxy-24-ethyl-6-oxa-B-homo-5α-cholestan-6-one.

35. A process for the manufacture of a compound as claimed in claim 1, conducted substantially as described herein.

36. A process for the manufacture of a compound of the general formula I given in claim 1, in which Z has the meaning given in claim 1 and R2, R3 and R22 each represents a hydrogen atom or an acyl group, with the proviso that at least one of the symbols R2, R3 and R22 represents an acyl group, wherein a compound of the general formula II

in which Z has the meaning given above, is reacted with a carboxylic acid anhydride, if desired in the presence of a catalyst.

37. A process for the manufacture of a compound of the general formula I given in claim 1, in which Z has the meaning given in claim 1, R22 represents a hydrogen atom or an acyl group and R2 and R3 together represent a group of the formula

in which X and Y have meanings given in claim 1, wherein a compound of the general formula Ila

in which Z has the meaning given above and R22' represents a hydrogen atom or an acyl group, is reacted with a) boron trifluoride etherate, if desired dissolved in an organic solvent, b) orthoacetic acid triethyl ester, if desired in the presence of a catalyst, dissolved in an organic solvent, c) acetophenone in perchloric acid, or d) diethyl carbonate and a catalytic amount of sodium methoxide.

38. A preparation for regulating the growth of plants, which comprises at least one compound of the general formula I given in claim 1, in which Z, R2, R3 and R22 have the meanings given in claim 1, in admixture with an auxiliary.

39. A preparation as claimed in claim 38, wherein the compound of the general formula I is a compound as claimed in claim 2.

40. A preparation as claimed in claim 38, wherein the compound of the general formula I is the compound claimed in any one of claims 3 to 34.

41. A preparation for regulating the growth of plants, which comprises at least one compound of the general formula I given in claim 1, in which Z, R2, R3 and R22 have the meanings given in claim 1, in admixture or conjunction with a suitable carrier.

42. A preparation as claimed in claim 41, wherein the compound of the general formula lisa compound as claimed in claim 2.

43. A preparation as claimed in claim 41, wherein the compound of the general formula I is the compound claimed in any one of claims 3 to 34.

44. A preparation as claimed in any one of claims 41 to 43, which is in the form of a powder, a strewable preparation, granules, a solution, an emulsion or a suspension.

45. A preparation as claimed in any one of claims 41 to 44, which also contains one or more active substances selected from defoliants, plant-protecting agents, pesticides and herbicides other than compounds of the general formula I.

46. A preparation as claimed in any one of claims 41 to 45, wherein the total amount present of active substance or substances is approximately 10 to 80% by weight.

47. A preparation as claimed in any one of claims 41 to 46, which also contains one or more surface-active agents in a total amount of up to 20% by weight

48. Any one of the preparations as claimed in claim 41 and substantially as described in Table I herein.

49. Any one of the preparations as claimed in claim 41 and substantially as described in Example 16 herein.

50. A method of regulating the growth of a living plant, wherein the living plant and/or the area in the vicinity of the living plant is/are treated with a compound of the general formula I given in claim 1, in which Z, R2, R3 and R22 have the meanings given in claim 1.

51. A method as claimed in claim 50, wherein the treatment is carried out with a compound as claimed in claim 2.

52. A method as claimed in claim 50, wherein the treatment is carried out with the compound claimed in any one of claims 3 to 34.

53. A method as claimed in claim 50, wherein the treatment is carried out with a preparation as claimed in any one of claims 41 to 49.

54. A method as claimed in any one of claims 50 to 53, wherein a single compound of the general formula I is used for the treatment in an amount within the range of from 0.001 to 1 kg per hectare.

55. A method as claimed in any one of claims 50 to 53, wherein two or more compounds of the general formula I are used for the treatment in a total amount within the range of from 0.001 to 1 kg per hectare.

56. A method as claimed in any one of claims 50 to 55, wherein the plant is a leguminous plant.

57. A method as claimed in claim 56, wherein the leguminous plant is a soya bean plant.

58. A method as claimed in claim 50, conducted substantially as described in Example 1 5 or 1 6 herein.

59. A method of regulating the growth of plants in an area of land, wherein the area is treated with a compound of the general formula I given in claim 1, in which Z, R2, R3 and R22 have the meanings given in claim 1.

60. A method as claimed in claim 59, wherein the treatment is carried out with a compound as claimed in claim 2.

61. A method as claimed in claim 59, wherein the treatment is carried out with a compound claimed in any one of claims 3 to 34.

62. A method as claimed in claim 59, wherein the treatment is carried out with a preparation as claimed in any one of claims 41 to 49.

63. A method as claimed in any one of claims 59 to 62, wherein a single compound of the general formula I is used for the treatment in an amount within the range of from 0.001 to 1 kg per hectare.

64. A method as claimed in any one of claims 59 to 62, wherein two or more compounds of the general formula I are used for the treatment in a total amount within the range of from 0.001 to 1 kg per hectare.

65. A method as claimed in any one of claims 59 to 64, wherein the area of land is a crop area.

66. A method as claimed in claim 65, wherein the crop is a leguminous crop.

67. A method as claimed in claim 66, wherein the leguminous crop is a soya bean crop.

68. A method of dressing seeds, wherein the seeds are treated with a compound of the general formula I given in claim 1, in which Z, R2, R3 and R22 have the meanings given in claim 1.

69. A method as claimed in claim 68, wherein the treatment is carried out with a compound as claimed in claim 2.

70. A method as claimed in claim 68, wherein the treatment is carried out with a compound claimed in any one of claims 3 to 34.

71. A method as claimed in claim 68, wherein the treatment is carried out with a preparation as claimed in any one of claims 41 to 49.

72. A pack which comprises at least one compound of the general formula I given in claim 1, in which Z, R2, R3 and R22 have the meanings given in claim 1 , together with instructions for its use in regulating the growth of living plants.

73. A pack as claimed in claim 72, wherein the compound of the general formula I is a compound as claimed in claim 2.

74. A pack as claimed in claim 72, wherein the compound of the general formula I is the compound claimed in any one of claims 3 to 34.