308239-34-1

Ursolic acid (UA), a plant-derived compound, has many properties beneficial to health. In the present study, we synthesised three series of novel UA derivatives and evaluated their anti-Toxoplasma gondii activity both in vitro and in vivo. Most derivative

An unexpected route for the synthesis of N,N-dialkyl formamidines has been reported by the reaction of amines with N,N-dialkyl formamides and phenyl chloroformate.

The azavinylogous aminalester 3 reacts with primary amines to give amidines 5 and 6. In the reaction of 3 with aniline the azavinylogous amidine 7 is produced additionally to the amidine 5c. Ethylendiamine is formylated at both aminogroups, the bis-amidine 8 thus formed is transformed to the salts 9a,b. Benzoxazole and benzimidazole can be prepared from 3 and o-aminophenol and o-phenylenediamine, resp. Carboxylic acid amides, urea, thiourea, aromatic acid hydrazides 17 and the sulfonylhydrazide 19 are formylated by 3 at nitrogen to give N-acylated formamidines 14, 16, 18, 20. From 3 and aliphatic acid hydrazides 17 and alkylhydrazines, resp., can be obtained 1,2,4-triazole 21 and 1-alkyl-1,2,4-triazoles 22a,b, resp. N.N-Dimethylcyanacetamide (32) reacts with 3 and the orthoamide 4a, resp., to give a mixture of the formylated compound 34 and the amidine 33. The reaction conditions are of low influence on the ratio in which 33 and 34 are formed. The orthoamide 4b and 32 react to afford a mixture of the amidine 35 and the enamine 36. Hydrogen-sulfide acts on 3 giving N,N-dimethylthioformamide (37). From 3 and 1-alkynes 41 can be prepared the amidines 42. Hydrolysis of 42b affords phenylpropiolaldehyde (43). The alkylation of the aminalester 3 gives rise to the formation of vinylogous amidinium salts 1c and 1d, resp., additionally is formed the amide acetal 2a. The salt 1d can also be prepared from 3 and borontrifluoride-ether. Iodide reacts with N,N-dimethylformamide acetals 12a,b in an unclear, complicated manner giving orthoesters 53, N,N-dimethylformamide, alkyliodides, alcohols, ammonium iodides 46 and carbondioxide. The action of halogens on 3 affords the salts 1a,b,c,e,f depending on the chosen stoichiometric ratio. Aromatic aldehydes are suited for trapping azavinylogous carbenes formed on thermolysis of 3; 1,3-oxazoles 69 are the reaction products. From 3 and propionaldehyde the amidine 65 can be obtained with low yield. Carbondisulfide transforms 3 to the azavinylogous salt 66. The preparation of the azavinylogous orthoamide 4a is described. The thermolysis of 3 and 4a, resp., gives rise to the formation of the triaminopyrimidine 67. Treatment of 1a with lithium diisopropylamide affords the triaminopyrazine 68, which can also be obtained by thermolysis of 3 in the presence of sodium hydride. Azavinylogous carbenes are thought to be the intermediates. Wiley-VCH Verlag GmbH, 2000.