Antibiotic YC 73 of Pseudomonas origin. 3. Synthesis of thioformin analogues.
In the earlier paper of this series1}, it was reported that YG 73 (I) of a Pseudomonas origin was a cupric complex of an acidic substance named thioformin (II), which could be synthesized by treating N-methylhydroxylamine with potassium dithioformate. Soon after the structure determination of II, the fact that such a simple thiohydroxamic acid derivative as II possesses significant antimicrobial activity prompted us to synthesize structural analogues of II. The analogues represented in the general formula III were readily prepared by the following methods. R\ yS )N-Cf (III) ho/ \h Method A : Direct thioformylation of N-substituted hydroxylamines with potassium dithioformate.
The thiohydroxamate system
The natural occurrence of thiohydroxamates, their methods of preparation, reactivity, properties of their derivatives including Barton's esters and complexes during the last 25 years, as well as a survey of their biological properties are reported in this review. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:169–194, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10017
Interaction of Diclofop-Methyl and MCPA on Wild Oats (Avena fatua)
Diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate} loses part of its activity on wild oats (Avena fatua L.) when it is applied in combination with ester or amine formulations of MCPA {[4-chloro-o-tolyl)oxy] acetic acid.} Uptake of diclofop-methyl is reduced in the presence of commercial formulations of MCPA, particularly amine formulations, which are only partly compatible with the diclofop-methyl formulation. With added MCPA, regardless of formulation, hydrolysis of diclofop-methyl to the acid diclofop is slowed down, both in intact wild oat plants and in a crude leaf extract. At the same time, conversion of any acid formed to inactive conjugates is accelerated in the presence of MCPA. It is concluded that the loss of activity of diclofop-methyl by MCPA can be accounted for by the effects of MCPA on uptake and metabolic conversion of diclofop-methyl.