JPS6024791B2 - Novel pyrone derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to novel pyrone derivatives useful as plant growth inhibitors.

The present invention provides novel compounds of general formulas (1) and (〇) (in formula (1), R represents a hydrogen atom or a methyl group,
In formulas (1) and (0), RI represents a hydrogen atom, an alkyl group, or a pendyl group.

) is provided. Although various pyrone ring compounds are known in the literature, there have been no reports of physiologically active pyrones containing a carboxylic acid group in the molecule.

It was found that the compound of the present invention has a remarkable growth inhibiting effect on plants.

It is expected to be used as an agriculturally useful plant growth regulator, especially as a formicidizing agent. Rice is a typical agricultural crop in Japan and Southeast Asian countries, but this area is affected by typhoons almost every year, causing many rice plants to collapse and resulting in reduced yields. For this reason, there is a need for a so-called mackerel that lowers the height of rice plants and prevents them from falling over even in typhoons. The compounds of the present invention have the effect of shortening the internodes of rice and inhibiting growth, that is, have a post-heathing effect, and as a result of twilling, the rice becomes difficult to lodge, and it prevents a decrease in yield, so it is useful in agriculture.
The compound of the present invention can be produced, for example, by the method shown in the reaction formula below.

As is clear from the reaction formula, the compounds of general formula (1) and general formula (b) are in the relationship of structural isomers, and the compound in which R in general formula (1) is methyl and the compound of general formula (0) are the same starting material. More can be obtained. In the formula, R represents hydrogen, an alkyl group or a pendyl group.

That is, in the method of the present invention, malonic acid dylides are reacted with acetoacetic acid methyl ester to synthesize novel 4-hydroxy-2-pyrosos, which are then alkylated with diazomethane to form 4-methoxy-2-pyrones (1 ) and 2-methoxy4-pyrones (0) are obtained.

The malonic acid dihalides used as starting materials can be obtained by reacting the corresponding carboxylic acid with thionyl chloride at 40 to 5 pi.

The following may be cited as individual examples of these compounds: Malonic acid dichloride (b.p.56-60
qC/28 Hg), methylmalonic acid dichloride (b
．． p. 65-66℃/20 side Hg), ethylmalonic acid dichloride (b.p.67q0/22 side Hg), isobutylmalonic acid dichloride (b.p.83q0/16 side Hg), n-octylmalonic acid dichloride (b.p. ．．
4yo/62 skin Hg), benzylmalonic acid dichloride (b.p. 134°C/2 ratio kite Hg). Methyl acetoacetate, another starting material, is easily available industrially. Further, to explain in detail the production of the compound of the present invention, malonic acid dihalide and acetoacetic acid methyl ester are reacted with an inert solvent, such as an aromatic solvent such as benzene, toluene, xylene, or chlorinated benzenes, or an aliphatic carbonized solvent. 4-Hydroxy-2-pyrones can be obtained by heating in an ether such as hydrogen, dioxane, or tetrahydrofuran.

Methylation of 4-hydroxy-2-pyrones can be achieved by reaction with diazomethane in an inert solvent at room temperature.

The methylated product is usually obtained as a mixture of 4-methoxy-2-pyrones and 2-methoxy-4-pyrones in a ratio of 3:2, and can be separated by means such as recrystallization and chromatography. Next, the production of the compounds of the present invention will be explained with reference to Examples. Example 1 Production of 4-hydroxy-5-methoxycarbonyl-6-methyl-3-n-octyl-2-pyrone (compound 1)
-35 ml of octylmalonic acid dichloride, 17.7 ml of methyl acetoacetate, and 200 ml of benzene were mixed and refluxed for 3 hours.

After cooling, extract the reaction solution with saturated heavy water and remove the aqueous layer.
After acidifying with dilute hydrochloric acid, extraction with ethyl acetate, washing with water, dehydration with anhydrous sodium sulfate, and concentration under reduced pressure, the resulting koji was purified by silica gel chromatography using benzene-ethyl acetate (9:1). 6.4 hours of 4-hydroxy-5-methoxycarponyl-6-methyl-3-n-octyl-2-pyrone was obtained. Liquid at room temperature. m. p.
-10 to -5℃, NMR6 (CDC13): 2.59 (
9 days, S), 3.80 (2 days, S), 3.96 (spots, S)
), 7.28 (axis, m), 11.66 (IH, S). Elemental analysis value (calculated value in brackets): C% 64.85 (rat.
83), H%8. Pine (8.18). A compound of the following general formula was produced in the same manner as in Example 1.

Table I Example 2 4-methoxy-5-methoxycarbonyl-6-methyl-
3-Methyl-2-pyrone (compound 7) and 2-methoxy5-methoxycarponyl-6-methyl-3-methyl-
Preparation of 4-pyrone (Compound 8) 4-Hydroxy-5-methoxycarbonyl-6-methyl-3-methyl-2-pyrone was added to 100 ml of hexane to form a solution of 3.5 mol/base of diazomethane 20'. was gradually added and the reaction was carried out at room temperature for 2 days.

The reaction product was concentrated under reduced pressure and the resulting residue was purified by silica gel chromatography using benzene-ethyl acetate (7:3) to obtain 0.3% of Compound 7 having a melting point of 38-39.5°C.
0.4 volumes of Compound 8 having a melting point of 89-91°C were obtained. Compound 7: NM old 6 (CDC13): 2.20
(Fine, S), 2,32 (Fine, S), 3.80 (Spotted, S)
, 3.85 (3rd, S).

Elemental analysis values (calculated values in parentheses): C% 56.82 (56.59), H% 5.67 (5
．． 71).

Compound 8: NM old 6 (CDC13): 1.85 (milk day, S), 2.35 (fence, S), 3.89 (thin, S),
3, Tsunagi (Chichi, S). Elemental analysis values (calculated values in brackets)
: C% 56.66 (56.59), H% 5.87 (5
．． 71).

The compounds shown in Tables 2 and 3 were produced in the same manner as in Example 2. Table 2 Table 3 Next, the plant growth inhibitory activity of the compounds of the present invention will be explained with reference to the following biological test examples.

Test Example 1 Lettuce Growth Inhibition Test A certain amount of the test sample was dissolved in methanol and poured onto furnace paper in a petri dish (diameter 4) to evaporate the solvent, and then 1 part of distilled water was added.

The lettuce seeds were then germinated by keeping them on moist oven paper at 30°C for one day.
One nestling (lakes) was transferred onto the oven paper in the petri dish. After growing under white light for 3 days at 30 qo, the length of the stem was measured.

The results are shown in Table 4. Test Example 2 Rice seedling growth inhibition test A certain test sample was dissolved in methanol and placed in a cylinder (
The mixture was poured onto a furnace paper in a 2 x 1 mm container, and after the solvent was immediately evaporated, 1 inch of distilled water was added.

Next, 3,000 rice seeds were placed in distilled water for 3 days to germinate (0ryzaesativacv. Nipponbare).
Twelve grains were transferred into a cylinder. After growing under white light for 6 days at 30°C, the length of the stem was measured.

The results are shown in Table 4.

Table 4 (Note) The higher the inhibition rate, the greater the growth inhibition effect.

Claims (1)

[Claims] 1 General formula (I) or (II) ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (In formula (I), R represents a hydrogen atom or a methyl group, and formulas (I) and (II) A pyrone derivative represented by R represents a hydrogen atom, an alkyl group, or a benzyl group.