De-Qing Shi

Studies on the Wittig Reaction. XV. A Direct Preparation of ω-Unsaturated Bromides via Solid/Liquid Transferred Wittig Reactions of ω-Bromoalkyltriphenyl Phosphonium Salts with Aldehydes

Abstract A new approach to the synthesis of ω—unsaturated bromides was proposed using solid/liguid transferred Wittig reactions between ω—bromoalkyltripheny phosphonium Salt and aldehydes.

Synthesis and Herbicidal Activity of α-Amino Phosphonate Derivatives Containing Thiazole and Pyrazole Moieties

A series of novel α-amino phosphonate derivatives containing the thiazole and pyrazole moieties 3 were synthesized by the Mannich-type reaction of substituted pyrazole-aldehyde 1, 2-amino-5-ethoxycarbonyl-4-methyl-thiazole 2, and dialkyl phosphites or triphenyl phosphite in the presence of a Lewis acid such as magnesium perchlorate as the catalyst under solvent-free conditions. Their structures were clearly confirmed by spectroscopy data (IR, 1H NMR, 31P NMR, MS) and elemental analysis. The results of a preliminary bioassay (in vitro) indicated that some of the title compounds 3 possessed moderate herbicidal activities against dicotyledonous plants (Brassica campestris L) or monocotyledonous plants (Echinochloa crus-galli) at the concerntration of 100 mg/L. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Synthesis and Biological Activity of Novel Phosphonate Derivatives Containing of Pyridyl and 1,2,3-Triazole Rings

In order to search for novel agrochemicals with high activity and low toxicity, a series of phosphonate derivatives containing 1,2,3-triazolyl and pyridyl rings were synthesized using 2-chloro-5-(chloromethyl)-pyridine as the starting material. IR, 1 H NMR, 31P NMR, MS, and elemental analyses confirmed their structures. The crystal structure of 5a was determined by single crystal X-ray diffraction. Preliminary bioassays indicated that some of them possess good herbicidal and moderate fungicidal activities.

A Convenient Synthesis and Herbicidal Activity of N-phosphonoalkylpyrazolo[4,3-e][1,2,4]-triazolo[1,5-d]pyrimidines

An important building block, diethyl [(5-amino-4-cyano-3-methylsulfanyl-pyrazol-1-yl)–(4-fluorophenyl)methyl] phosphonate (3) was efficiently synthesized via the condensation of 1-hydrazino-1-(4-fluorophenyl)methyl phosphonate (1) with 2-[bis(methylthio)methylene]malononitrile (2).3 reacted with triethyl orthoformate to afford diethyl [(4-cyano-5-ethoxymethyleneamino-3-methylsulfanyl-pyrazol-1-yl)-(4-fluorophenyl)methyl] phosphonate (4), which reacted with various acyl hydrazines in refluxing 2-methoxyethanol to provide the target compounds (5) in good yields directly. The results of preliminary bioassay indicated that compounds 5 possess potent herbicidal activity against the roots of monocotyledonous (barnyard grass) and dicotyledonous (oil rape) plants, and could be further developed as potential herbicides.

Synthesis and Herbicidal Activity of O,O-Diethyl N-{4-Methyl-[1,2,3]thiadiazole-5-carbonyl}- 1-amino-1-substitutedbenzyl Phosphonates

Target compounds 3 were synthesized by the condensation of O,O-diethyl α-amino substitutedbenzyl phosphonates 1 and 4-methyl-[1,2,3]thiadiazole-5-carboxylic acid 2 in the presence of dicyclohexylcarbodiimide (DCC) as a dehydration reagent. Their structures were confirmed by spectroscopic data (IR, 1H NMR, 31P NMR, MS) and elemental analysis. The results of a preliminary bioassay (in vitro) indicated that some of the title compounds 3 possessed moderate to good herbicidal activities against dicotyledonous plants (Brassica campestris L) at the concentration of 100 mg/L, and most of these compounds exhibited higher herbicidal activities against dicotyledonous plants (Brassica campestris L) than monocotyledonous plants (Echinochloa crus-galli). Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.

Synthesis and Biological Activities of Novel Thiazole Derivatives of DHPMs via the N, S-dialkylation

A series of novel 1-[6-aryl-1-(2-chlorothiazol-5-yl-methyl)-2-(2-chlorothiazol-5-yl -methylsulfanyl)-4-methyl-1,6-dihydropyrimidin-5-yl]carboxylates or ethanones 2 were synthesized via the N,S-dialkylation of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) 1 using 2-chloro-5-(chloromethyl)thiazole as the alkylation reagent in one-pot reaction. The structures of the target compounds were confirmed by IR, 1H NMR, EI-MS and elemental analyses, and, in the case of 2c, by single crystal X-ray diffraction. The preliminary bioassay indicated that the title compounds 2 possess moderate to weak fungicidal and insecticidal activities.

Synthesis and Herbicidal Activity of O,O-Dialkyl(phenyl)-N-{1-[(6-chloropyridin-3-yl)methyl]-4-cyano-1H-1,2,3-triazol-5-yl}-1-amino-1-substitutedbenzyl-phosphonates

Abstract A series of novel α-amino phosphonate derivatives containing both pyridine and 1,2,3-triazole moieties 4 were synthesized via a multi-step reaction. First, the condensation of 5-amino-1-[(6-chloropyridin-3-yl) methyl]-4-cyano-1H-1,2,3-triazole with various aromatic aldehydes in the presence of magnesium perchlorate afforded imines 3 in moderate yields; second, imines 3 reacted with dialkyl phosphites or triphenyl phosphite to give the title compounds 4 in moderate to good yields. Their structures were elucidated by spectroscopic data (IR, 1H NMR, 31P NMR, ESI-MS) and elemental analysis. The preliminary bioassay (in vitro) indicated that some of the title compounds 4 possessed moderate herbicidal activities against dicotyledonous plants (Brassica campestris L) at a concentration of 100 mg/L. However, compounds 4 did not exhibit herbicidal activities against Brassica campestris L at a concentration of 10 mg/L. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT

Synthesis and Biological Activities of O-Alkyl, O-Aryl, O-{Z-[1-Phenyl-2-(1H-1,2,4-triazol-1-yl)ethylidene]amino} Phosphorothioates

A series of title compounds 2 were efficiently synthesized via the condensation of 1-phenyl-2-(1H-1,2,4-triazol-1-yl)ethanone oxime with various asymmetric thiophosphoryl chlorides in sodium hydroxide powder and acetonitrile system. The structures of title compounds 2 were confirmed by IR, 1H NMR, 31P NMR, EI-MS, and elemental analysis. The results of preliminary bioassays indicated that the title compounds 2 possessed good to moderate insecticidal activity against aphides at the dosage of 250 mg/L, and some of them exhibited moderate fungicidal activities at the concentration of 100 mg/L.

Synthesis and Herbicidal Activity of Novel Pyrimidinyl Derivatives Containing an α-Amino Phosphonate Moiety

In order to find novel pyrimidinyl carboxylic acid analogs with high activity and low toxicity, a series of novel pyrimidinyl derivatives containing an α-amino phosphonate moiety 5 was synthesized by the condensation of 4-(4,6-dimethoxypyrimidin-2-yloxy)phenoxyacetic 3a or propionic acids 3b with dialkyl α-amino substitutedbenzyl phosphonates 4. Their structures were characterized by spectroscopic data (IR, 1H NMR, 31P NMR, MS) and elemental analyses. The results of preliminary herbicidal activities (in vitro) showed that most of these compounds exhibited higher herbicidal activities against dicotyledonous weeds (Brassica campestris L) than monocotyledonous weeds (Echinochloa crus-galli). Further bioassays (in vivo) indicated that some of compounds 5 possessed selective herbicidal activity against amaranth pigweed (A. retroflexus) in post-emergence treatment. Supplemental materials are available for this article. Go to the publishers online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.