Synthesis and acaricidal activity of cyenopyrafen
and its geometric isomer
Haibo Yu, Man Xu, Yan Cheng, Hongfei Wu, Yanmei Luo, and Bin Li*
State Key Laboratory of the Discovery and Development of Novel Pesticide,
Shen Yang Rearch Institute of Chemical Industry Co. Ltd., Shenyang 110021,
People’s Republic of China
E-mail:
Abstract
Cyenopyrafen and its geometric isomer were synthesized by various methods, and the structures were characterized by 1H NMR. 13C NMR, IR, elemental analys and X-ray diffraction analys. The bioassay tests showed that cyenopyrafen exhibited a higher acaricidal activity than its isomer. Cyenopyrafen can be isomerized from the Z form in the prence of a ba.
小旺财
Keywords: Cyenopyrafen, geometric isomer, synthesis, acaricidal activity
Introduction
香肠可以炒什么菜
Nissan Chemicals Co. has been investigating the incticidal, acaricidal, nematicidal and aquatic antifouling properties of acrylonitrile derivatives since 1995. In January 2006, cyenopyrafen was provisionally approved for the ISO name of a new acaricide. Cyenopyrafen is the first commercialized acrylonitrile derivative with important acaricidal activity against spider mites (Tetranychus cinnabarinus). It has also a high safety level on beneficial incts such as honey bees.1,2 In 2009, cyenopyrafen was launched under the trade name Starmite, besides in Japan, it is also ud in Korea.
Figure1. Cyenopyrafen (CODE NOS: NC-512).拳击绷带
The double bond in the acrylonitrile compounds can occur as two geometric isomers referred to as the E- and Z-isomer. Cyenopyrafen exits in the E configuration. The properties of both of them, with regard to physiological activity, safety and physical properties often differ from each other.3,4In order to study the differences of their biological activity of cyenopyrafen and its geometric isomer, the synthesis of the two isomers was conducted by two methods, and the acaricidal activity relationship
大行星of cyenopyrafen and its Z isomer was discusd. In order to reu the Z isomer, we also studied the method of isomerization from Z- to the E-isomer.
Result and Discussion
Chemistry
财产证明
2-(4-tert-Butylphenyl)-3-hydroxy-3-(1,3,4-trimethyl-1H-pyrazol-5-yl)acrylonitrile 3 was prepared according to Scheme 11,3,4-trimethyl-1H-pyrazole-5-carboxylate 15-12and 2-(4-tert-butylphenyl)acetonitrile 2were subjected to the condensation reaction using sodium methoxide as ba to give 3-hydroxyacrylonitrile 3 in good (90%) yield.13,14
Scheme 1. Synthesis of 2-(4-tert-butylphenyl)-3-hydroxy-3-(1,3,4-trimethyl-1H-pyrazol-5- yl)acrylonitrile 3.
琐碎的近义词
分米
To synthesize cyenopyrafen or its geometric isomer as the major product, two methods were explored (Scheme 2 and 3). Cyenopyrafen 4 was synthesized as described in the literature and can readily be achieved by the reaction of 3-hydroxyacrylonitrile 3 with 2,2-dimethyl propionyl
chloride in the prence of a ba such as Et3N at room temperature (Scheme 2) in good (93%) yield.14A new method consisted in the synthesis of cyenopyrafen’s geometric isomer 5by reacting 3-hydroxyacrylonitrile 3 with 2,2-dimethylpropionic acid via a Steglich esterification in the prence of DMAP at room temperature in 65% yield, using DCC as a dehydration reagent (Scheme 3). The carboxylic acid reacts with DCC to a O-acyl isourea, which is more reactive than the free acid. The alcohol attacks this intermediate, forming DCU and the corresponding ester. To suppress this reaction, DMAP is added, acting as an acyl transfer-reagent. The reaction mechanism is described in Scheme 4.
Scheme 2. Synthesis of (2E)-3-(2,2-dimethypropanoyloxy)-2-(4-tert-butylphenyl)-3-(1,3,4- trimethylpyrazol-5-yl)acrylonitrile 4 (cyenopyrafen).
Scheme 3.Synthesis of (2Z)-3-(2,2-dimethypropanoyloxy)-2-(4-tert-butylphenyl)-3-(1,3,4- trimethylpyrazol-5-yl)acrylonitrile 5 (Z form).
In order to valorize the Z form, we also studied the isomerization from the Z form to the E form. Cyenopyrafen 4 can be obtained by isomerization from the Z form 5in a polar solvent, such as acetonitrile and methanol under heating conditions, in 48% yield in the prence of an organic ba, such as pyridine or DMAP (Scheme 5). The isomerization was catalyzed by paramagnetic molecules DMAP and the possible mechanism was shown in scheme 6.19
一应俱全Scheme 4. Mechanism of synthesis 5.
Scheme 5. Isomerization from the Z form 5 to c yenopyrafen 4.
Scheme 6. Possible mechanism of isomerization.
The synthesized compounds were identified by 1H NMR, 13C NMR, IR, and elemental analys is. The characteristic signals resulting from the C≡N group of cyenopyrafen and its isomer are at 115.29 and 116.21 ppm respectively in the. 13C NMR spectrum and IR spectra displayed a strong C≡N group absorption at 2210 and 2220 cm-1. In order to further confirm the structure of the cyenopyrafen and its isomer, the X-ray diffraction analys were carried out. The crystal structures of cyenopyrafen and its isomer are shown in Figure 2 and 3.
Figure 2. The crystal structure of cyenopyrafen 4 (E form).
Figure 3. The crystal structure of cyenopyrafen’s isomer 5 (Z form).
