A variety of 2-amino-, 2-anilino-and 2-acylamino-1 ,Cnaphthoquinones, with hydrogen, chlorine, alkoxy, phenoxy, methylthio or phenylthio as the 3-substituent, have been synthesised and assayed against Botrytis cinerea, Cladosporium fulvum and Venturia inaequalis. With few exceptions, only the 2-acylamino compounds possessed appreciable fungicidal activity: this was of a high order in the cases of 2-prop-ionamido-, 2-N-methylacetamido-3-methylthio-, and 3-methoxy-2-Nmethylacetamido-1 ,Cnaphthoquinones.
Experimental methods
Chemical techniquesThe purity of reaction products was routinely monitored by thin-layer chromatography on pre-coated aluminium foil (silica gel 60 F254, Merck); the eluent was toluene+ethanol (9+1 by volume). New compounds were characterised by infrared spectroscopy and elemental analysis; percentage compositions were confirmed within a tolerance of 0.3% for C, H, N and, where appropriate, S and the halogens. N-Substituted 2-amino-1,4-naphthoquinones (compounds I-XVII) The parent 2-amino-1,4-naphthoquinone was obtained by the action of sodium azide on 1,4-naphthoq~inone.~~ The N-alkyl derivatives were prepared by oxidising the dihydro adducts from alkylamines and 1,4-naphthoquinone with air, in the presence of copper(I1) salts.34 In the case of the N-aryl compounds, the dihydro intermediate was oxidised by using 2 mol of 1,Cnaphthoquinone to 1 mol of aniline.35 All the compounds formed red prisms. 23 24 N. G . Clark
2.2.