A NOVEL SYNTHESIS OF TETRAAMINOETHENES BY REDUCTION OF OXALIC AMIDINES AND SUBSEQUENT ELECTROPHILIC SUBSTITUTION

Reduction of the 1,4-diaza-1,3-butadiene substructure of hexasubstitut ed amidines 1 with Lithium metal yields the dilithium diamides 2. Subs equent reactions of these with various electrophiles give the title su bstances 3, 4 and 5. The quenching reaction of 2 with organosilicon de rivatives leads to open-chain 3b as well as to cyclic tetraaminoethene s 4a,b. Treatment of 2 with methanol gives 3a which in the presence of oxygen is reoxidized to the starting amidine 1. Using alkyl halides a s electrophiles, compounds 3c-e and 4c,d could be obtained in moderate to good yields. X-ray structural analyses of derivatives 3e and 4c re veal sterically overloaded central C-C double bonds. Whereas phosgene and its thio derivative give the imidazolines 4e,f, methyl benzoate al lows a stepwise substitution leading to tetraaminoethenes bearing diff erent residues at the nitrogen atoms.