Fungicidal 2,6,6′-trimethylbenzophenones

Details Fungicidal 2,6,6′-trimethylbenzophenones Fungicidal 2,6,6′-trimethylbenzophenones

1998-08-05

2001-06-05

Qazi, Sabiha N. (Department: 1616)

Drug, bio-affecting and body treating compositions

Designated organic active ingredient containing

Ketone doai

C514S687000, C568S333000

Reexamination Certificate

active

06242498

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to certain 2,6,6′-trimethylbenzophenone compounds, a novel process for their preparation, compositions containing such compounds, a method for combating a fungus at a locus comprising treating the locus with such compounds and their use as fungicides.
Food production relies upon a variety of agricultural technologies to ensure the growing population's dietary needs remain affordable, nutritious and readily available on grocery store shelves. Fungicides are one of these agricultural technologies which are available to the world community. Fungicides are agrochemical compounds which protect crops and foods from fungus and fungal diseases. Crops and food are constantly threatened by a variety of fungal organisms, which, if left uncontrolled, can cause ruined crops and devastated harvests.
In particular, ascomycetes, the causative agent for powdery mildew diseases are an ever-present threat especially to cereal and fruit crops. However, applications of fungicidal agents at disease control rates can cause phytotoxic damage to the target plants.
The compounds of the present invention are disclosed in a broad general formula of the European patent (“EP”) application EP 0 727 141, which published on Aug. 21, 1996. The EP application discloses compounds having activity against phytopathogenic fungi, but relatively low systemicity.
There is no disclosure in the EP application of substituted benzophenones, wherein the first phenyl group is substituted by two methyl groups in the
2
- and
6
-position and an additional substituent in the 3-position.
Moreover, there is no hint given to a one-step process in which a methoxy group in the 2-position of the second phenyl group is directly replaced by an alkoxy group.
SUMMARY OF THE INVENTION
The present invention provides a process for the preparation of a compound of formula I,
in which
R
1
represents an optionally substituted C
2
-C
6
alkyl, benzyl, cyclohexylmethyl or C
3
-C
6
alkenyl group, and
R
2
represents a hydrogen or a halogen atom, or an optionally substituted alkoxy group or a nitro group, which comprises reacting a compound of formula II,
wherein R
2
has the meaning given, with a compound of formula III,
R
1
—O—Met  (III)
wherein R
1
has the meaning given and Met denotes an alkali metal atom.
Moreover, the present invention relates to novel compounds of compound of formula IA:
wherein R
1
has the meaning given above, and R
2
represents a halogen atom, or an optionally substituted alkoxy group or a nitro group.
Furthermore, the present invention relates to novel compounds of formula IIA:
wherein R
2
represents a halogen atom, or an optionally substituted alkoxy group or a nitro group.
The compounds combine relatively excellent selective fungicidal activities in various crops with comparably high systemicities.
It is an object of the present invention to provide highly systemic fungicidal compounds.
It is also an object of the invention to provide methods for controlling an undesired fungus by contacting said plants with a fungicidally effective amount of the compounds.
It is another object of the invention to provide selective fungicidal compositions containing the compounds as active ingredients.
These and other objects and features of the invention will be more apparent from the detailed description set forth hereinbelow, and from the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It has surprisingly been found that the compounds of formula I
can easily be prepared from compounds of formula II
by reaction with a compound of formula III
R
1
—O—Met  (III)
in which R
1
, R
2
, and Met have the meaning given above, in high yields. The R
1
—O group selectively substitutes the methoxy group attached in the 2-position with respect to the benzoyl group without affecting the methoxy groups attached in the 3- and 4-position of the right-hand phenyl group. The compounds of formulae IA and IIA, which correspond to formulae I or II, but in which the radical R
2
is different from hydrogen, combine relatively excellent fungicidal activity against phytopathogenic fungi even at low dose rates, in particular those that cause powdery mildew diseases and have comparably high systemicity.
In general terms, unless otherwise stated, as used herein the term halogen atom may denote a bromine, iodine, chlorine or fluorine atom, and is especially a bromine, chlorine or fluorine atom.
Optionally substituted moieties may be unsubstituted or have from one up to the maximal possible number of substituents. Typically, 0 to 2 substituents are present. Each optionally substituted group independently is substituted by one or more halogen atoms or nitro, cyano, cycloalkyl, preferably C
3-6
cycloalkyl, cycloalkenyl, preferably C
3-6
cycloalkenyl, haloalkyl, preferably C
1-6
haloalkyl, halocycloalkyl, preferably C
3-6
halocycloalkyl, alkoxy, preferably C
1-6
alkoxy, haloalkoxy, preferably C
1-6
haloalkoxy, phenyl, mono- di- or trihalo-phenyl or pyridyl groups.
In general terms, unless otherwise stated herein, the terms alkyl, alkenyl and alkoxy as used herein with respect to a radical or moiety refer to a straight or branched chain radical or moiety. As a rule, such radicals have up to 10, in particular up to 6 carbon atoms. Suitably an alkyl or alkoxy moiety has from 1 to 6 carbon atoms, preferably from 1 to 5 carbon atoms. A preferred alkyl moiety is the methyl, ethyl, n-propyl, isopropyl or n-butyl group.
The invention especially relates to compounds of the general formulae IA and IIA in which any alkyl part of the groups R
1
and R
2
, which may be straight chained or branched, contains 1 to 10 carbon atoms, preferably 1 to 9 carbon atoms, more preferably 1 to 6 carbon atoms, and in which each optionally substituted group independently is substituted by one or more halogen atoms or nitro, cyano, cycloalkyl, preferably C
3-6
cycloalkyl, cycloalkenyl, preferably C
3-6
cycloalkenyl, haloalkyl, preferably C
1-6
haloalkyl, halocycloalkyl, preferably C
3-6
halocycloalkyl, alkoxy, preferably C
1-6
alkoxy, haloalkoxy, preferably C
1-6
haloalkoxy, phenyl, or pyridyl groups, in which the phenyl moiety is optionally substituted by one to three substituents selected from halogen atoms, cyano, C
1-6
alkyl and C
1-6
alkoxy groups.
The invention especially relates to compounds of the general formula IA in which R
1
represents a straight-chained or branched C
2-10
alkyl, in particular a straight-chained C
2-6
alkyl group, most preferably being anethyl, n-propyl, n-butyl, n-pentyl group or a phenylmethyl group, in which the phenyl moiety may be unsubstituted or substituted by 1 to 5, preferably 1 to 3, substituents selected from the group consisting of halogen atoms, alkyl, alkoxy, haloalkyl and haloalkoxy groups.
The invention especially relates to compounds of the general formulae IA and IIA in which R
2
represents a halogen atom, in particular a fluorine, chlorine, bromine or iodine atom, a nitro, a C
1-10
alkoxy or a C
1-10
haloalkoxy group, most preferred being a chlorine or bromine atom or a nitro or methoxy group.
The benzophenone compounds according to formulae IA and IIA are oils, gums, or, predominantly, crystalline solid materials and possess valuable fungicidal properties. For example, they can be used in agriculture, or related fields such as horticulture and viticulture, for the control of phytopathogenic fungi, especially ascomycetes, in particular powdery mildew diseases such as those caused by
Erysiphe graminis, Podosphaera leucotricha, Uncinula necator
and the like. Said benzophenone compounds possess a high fungicidal activity over a wide concentration range and may be used in agriculture without harmful phytotoxic effects.
Moreover, the compounds according to the invention show enhanced curative and residual control of fungi and fungal diseases such as cereal, cucumber and grape powdery mildew, and improved foliar systemicity compared with conventional fungicides.
Useful results in terms of control of phythopathogenic f

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