57225-86-2Relevant articles and documents
Synthesis and stereostructure-activity relationship of novel pyrethroids possessing two asymmetric centers on a cyclopropane ring
Taniguchi, Takashi,Taketomo, Yasuaki,Moriyama, Mizuki,Matsuo, Noritada,Tanabe, Yoo
supporting information, (2019/03/26)
2-Methylcyclopropane pyrethroid insecticides bearing chiral cyanohydrin esters or chiral ethers and two asymmetric centers on the cyclopropane ring, were synthesized. These compounds were designed using a “reverse connection approach” between the isopropyl group in Fenvalerate, and between two dimethyl groups in an Etofenprox analogue (the methyl, ethyl form), respectively. These syntheses were achieved by accessible ring opening reactions of commercially available (±)-, (R)-, and (S)-propylene oxides using 4-chlorobenzyl cyanide anion as the crucial step, giving good overall yield of the product with >98% ee. The insecticidal activity against the common mosquito (Culex pipiens pallens) was assessed for pairs of achiral diastereomeric (1R*,2S*)-, (1R*,2R*)-cyanohydrin esters, and (1R*,2S*)-, (1R*,2R*)-ethers; only the (1R*,2R*)-ether was significantly effective. For the enantiomeric (1S,2S)-ether and (1R,2R)-ether, the activity was clearly centered on the (1R,2R)-ether. The present stereostructure?activity relationship revealed that (i) cyanohydrin esters derived from fenvalerate were unexpectedly inactive, whereas ethers derived from etofenprox were active, and (ii) apparent chiral discrimination between the (1S,2S)-ether and the (1R,2R)-ether was observed. During the present synthetic study, we performed alternative convergent syntheses of Etofenprox and novel 4-EtO-type (1S,2S)- and (1R,2R)-pyrethroids from the corresponding parent 4-Cl-type pyrethroids, by utilizing a recently-developed hydroxylation cross-coupling reaction.
Synthesis and Applications of Unquaternized C-Bound Boron Enolates
Ng, Elvis Wang Hei,Low, Kam-Hung,Chiu, Pauline
, p. 3537 - 3541 (2018/03/21)
A general and facile method to prepare unquaternized C-bound boron enolates by a ligand-controlled O-to-C isomerization is reported. Using this protocol, C-bound pinacolboron enolates have been isolated in pure form for the first time, and have been fully characterized by NMR spectroscopy and X-ray crystallography. In contrast to the general perception, such C-boron enolates are stable without coordinative saturation at the boron. Moreover, C-boron enolates present reactivities that are distinct from the O-boron enolates, and their applications in C-O and C-C bond formations are demonstrated.
Synthesis and biological activities of a novel series of 3,6-disubstituted-1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazoles containing gem-dimethylbenzyl moiety
Puthiyapurayil, Pushpan,Poojary, Boja,Kumar, Sunil,Hunnur, Raveendra
experimental part, p. 998 - 1005 (2011/11/06)
A novel series of 3,6-disubstituted-1,2,4-triazolo-[3,4-b]-1,3,4- thiadiazoles (6a-r) containing gem-dimethyl benzyl moiety were prepared by the condensation of 4-amino-3-aryl/aralkyl substituted-5-mercapto-1,2,4-triazoles (5a-c) with various fluoro substituted aromatic acids in the presence of POCl3. IR, 1H NMR, 13C NMR, 2D NMR (COSY), and mass spectral data confirmed the structures of all the synthesized compounds. All the compounds were also screened for their antibacterial, antifungal and analgesic activities. Compounds 6b, 6d, 6f, 6g, 6h, 6i, 6m, 6n, 6o, 6p, and 6r exhibited promising antibacterial and compounds 6a, 6d, 6f, 6g, 6h, 6k, 6m, 6o, 6p, and 6q showed significant analgesic activities.
