- Synthesis of Pyrroles via Consecutive 6π-Electrocyclization/Ring-Contraction of Sulfilimines
-
We present a modular, synthetic entry to polysubstituted pyrroles employing readily available 2,5-dihydrothiophenes. Ring-opening of the heterocycle provides access to a panel of 1,3-dienes which undergo pyrrole formation in the presence of inexpensive chloramine-T trihydrate. The transformation is conducted in an open flask and proceeds at ambient temperatures (23 °C) in nondry solvents. A careful adjustment of the electronics and sterics of the 1,3-diene precursor allows for the isolation of key intermediates. DFT studies identified a reaction mechanism that features a 6π-electrocyclization of a sulfilimine intermediate followed by spontaneous ring-contraction to reveal the pyrrole skeleton.
- Feichtinger, Niklas J.,Haut, Franz-Lucas,Müller, Mira,Magauer, Thomas,Plangger, Immanuel,Podewitz, Maren,Streit, Tim-Niclas,Wein, Lukas A.,Wurst, Klaus
-
p. 9002 - 9008
(2021/07/01)
-
- Preparation method of fludioxonil
-
The invention relates to the field of bactericides, and discloses a preparation method of fludioxonil. The preparation method of fludioxonil comprises the following steps: carrying out a first contactreaction on 2,2-difluoro-1,3-benzodioxo-4-aldehyde and cyanoacetate under the catalysis of a first alkali to obtain a product after the first contact reaction, and directly carrying out a second contact reaction on the product after the first contact reaction and tosylmethyl isocyanidee. According to the technical scheme, the preparation method used for obtaining fludioxonil and having the advantages of easiness in industrialization, cheap and easily available raw materials, less three wastes, high reaction yield and high purity can be provided.
- -
-
Paragraph 0060-0084
(2020/07/06)
-
- A method for preparing Fludioxonil
-
The invention relates to the field of organic synthesis and discloses a method for preparing Fludioxonil. Fludioxonil has a structure represented by a formula (VIII) shown in the description. The method is characterized by comprising the step of enabling a 2-cyano-3-(2,2-difluoro-1,3-benzodioxy-4-yl)acrylic acid compound represented by a formula (I) shown in the description to be in contact reaction with p-methylbenzenesulfonyl methyl isocyanide represented by a formula (VII) shown in the description in a solvent in the presence of alkali, wherein the rate of change of the pH value of a reaction solution during reaction is lower than 1 per minute, the pH value is controlled in the range of 10-14.0, R1 is NHR2 or OR3, R2 is H or C1-C6 alkyl, and R3 is C1-C6 alkyl. The yield of the Fludioxonil product prepared by the method disclosed by the invention can reach over 95%, the purity of the product can reach over 98wt%, and the content of difficultly-removed impurities, i.e., M305 and M319 in the product can be lower than 0.1 wt%; and the prepared Fludioxonil product is white, so that the step and cost for dealing with color problems are avoided.
- -
-
-
- 4 - (2,2-difluoro -1,3-Benzodioxole-4-yl) pyrrole-3-nitrile synthetic method
-
The invention discloses a synthetic method of 4-(2,2-difluoro-1,3-benzodioxole-4-yl)pyrrole-3-nitrile. The method comprises the following steps of: preparing an intermediate 2,2-difluorobenz-1,3-dioxole through reacting catechol with dibromodifluoromethane, and preparing an intermediate 2-cyano-3-(2,2-difluorobenz-1,3-dioxole-4-yl)-2-acrylate. The fludioxonil prepared by the synthetic method provided by the invention has the purity of more than 99.0% and the total yield of more than 45.0%; the synthetic method has the advantages of cheap and easily available raw materials, simple process, high product yield in each step, good purity, low production cost, applicability to batch industrial production and the like.
- -
-
-
- Process for the preparation of substituted difluorobenzo-1,3-dioxoles
-
The reaction of 2,2-difluorobenzo-1,3-dioxole with (a) an alkali metal or an alkali metal compound and then (b) a compound R1 -Z1 l in which Z1 is a leaving group, or with an aldehyde produces compounds of formula I STR1 wherein R1 l is --OH, --SH, --CHO, --CN, --COOH, --B(OH)2, --COX, with X being Cl or Br, or is --COOR2, --SiR32 or --B(OR2)2, with R2 being a C1 -C12 alcohol moiety without the hydroxy group, wherein R1 is further --Cn H2n COOR2, with n being an integer from 1 to 4, or linear or branched C1 -C12 hydroxyalkyl which is unsubstituted or is substituted by --F, --CN, C1 -C6 alkoxy, phenyl, fluorophenyl, C1 -C4 alkoxy-phenyl, C1 -C4 alkylthio-phenyl, C1 -C4 alkyl-phenyl, C1 -C4 fluoroalkyl-phenyl, nitrophenyl or by cyanophenyl, or wherein R1 is a benzyl alcohol which is unsubstituted or is substituted by F, C1 -C4 alkoxy, C1 -C4 alkylthio, C1 -C4 alkyl, C1 -C4 fluoroalkyl, nitro or by cyano, or is C1 -C12 acyl, or wherein R 1 is a radical of formula II STR2 wherein R5 is --CN, --CF3, --COOR2, --CO--NHR2 or --CONR22, R3 and R4 are a direct bond or each is H, or R3 is H and R4 independently has the meanings of R5, or R3 and R4 together are --CH2 --NR6 --CH2 --, --CH2 --NR6 --CO-- or --CO--NR6 --CO-- wherein R6 is the radical of a removable protecting group, or wherein further R1 is a radical of formula III STR3 Insecticides or fungicides can be prepared from the compounds of formula I. 3-(2,2-difluorobenzodioxol-4-yl)-4-cyanopyrrole can be prepared by reacting 4-metallo-2,2-difluorobenzodioxole (III) with an unsaturated nitrile and then with a sulfonylmethyl isocyanide in a one-pot process. The compounds III are novel intermediates.
- -
-
-
- Difluorbenzodioxyl cyanopyrrole microbicidal compositions
-
The invention relates to novel 3-phenyl-4-cyanopyrrole derivatives of the general formula STR1 wherein X has the following meaning: A: hydrogen or CO--R1, wherein R1 is C1 -C6 alkyl which is unsubstituted or substituted by halogen or C1 -C3 alkoxy; or is C3 -C6 alkenyl, C3 -C6 alkylnyl, or C1 -C6 alkoxy which is unsubstituted or substituted by halogen or C1 -C3 alkoxy; or is C3 14 C6 alkenyloxy, or C3 -C6 cycloalkyl; B: S--R2, wherein R2 is C1 -C3 haloalkyl; C: CH(Y)R3, wherein R3 is hydrogen or C1 -C8 haloalklyl and Y is hydroxy, halogen or OC(O)R4, wherein R4 is C1 -C8 alkyl, C1 -C8 haloalkyl, C2 -C6 alkenyl, or C1 -C6 alkoxycarbonyl; or D: CH2 --Z, wherein Z is the group STR2 in which formula each of R5 and R6 independently of the other is hydrogen, C1 -C6 alkyl which is unsubstituted or substituted by cyano or C1 -C6 alkoxycarbonyl; or is C3 -C6 alkenyl, C3 -C6 alkynyl, C3 -C7 cycloalkyl, or phenyl which is unsubstituted or substituted by halogen, C1 -C6 alkyl, C1 -C6 haloalkyl or C1 -C6 alkoxy, with the proviso that only R5 or R6 may be hydrogen.
- -
-
-