- Tetrazolinone derivatives
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Herbicidal novel tetrazolinone derivatives of the formula: STR1 wherein R1 is alkyl, haloalkyl, cycloalkyl, alkenyl, haloalkenyl, alkynyl, alkoxy or phenyl which is optionally substituted, and R2 is alkyl, haloalkyl, cycloalkyl, alkenyl, haloalkenyl, alkynyl, alkoxy or phenyl which is optionally substituted, or R1 and R2 form, together with the nitrogen atom to which R1 and R2 are bonded, a 5- or 6-membered heterocyclic ring, optionally fused to a carbocyclic ring optionally and independently substituted by C1-4 alkyl, and R3 is a 5-membered heterocyclic radical containing at least one hereto atom selected from the group consisting of nitrogen, oxygen, and sulfur, optionally substituted by at least one substitutent selected from the group consisting of halogen, benzyl, phenyl, halogen-substituted phenyl, C1-4 alkyl, C1-4 alkoxy, C1-4 haloalkyl, C1-4 haloalkoxy, C1-4 alkylthio, C1-4 alkyl-sulfonyl and C3-8 cycloalkyl, processes for their preparation and novel intermediates therefor.
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- Preparation and Cycloaddition of Thienyl Isocyanates with Trimethylsilyl Azide: One-pot Synthesis of Thienyltetrazolin-5-ones
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Efforts to prepare thienyl isocyanates by thermal reactions of thenoyl chlorides with trimethylsilyl azide (TMSA) led preferentially to the formation of 1,4-disubstituted tetrazolin-5-ones, arising by interaction of the initially formed thienyl isocyanate with TMSA.In fact, 2-thenoyl chloride and benzothiophene-2-carbonyl chloride reacted with 1 equiv.TMSA in refluxing carbon tetrachloride to give 1-(2-thienyl or benzothienyl)-4-(2-thenoyl or benzothiophenecarbonyl)tetrazolin-5-one 4d, e, whereas 3-thenoyl chloride led to 1-(3-thienyl)-4-trimethylsilyltetrazolin-5-one adduct II which was converted, after hydrolytic desilylation, to 1-(3-thienyl)tetrazolin-5(4H)-one 4c.Similar reactions, carried out with more than two equiv. of TMSA, led in all cases to the formation of the corresponding 1-heteroaryltetrazolin-5-one 4a-c via the corresponding silylated tetrazolin-5-ones II, whereas at room temp. such reactions gave essentially thenoyl azides which, after elimination of the excess TMSA, were thermally converted to the corresponding thienyl isocyanates 3 in fairly good yields.
- Toselli, Maurizio,Zanirato, Paolo
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p. 1101 - 1104
(2007/10/02)
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