SYNTHESIS OF CARBORANYL AMINO-ACIDS, HYDANTOINS, AND BARBITURATES

The syntheses of three novel boronated hydantoins, 5-(o-carboran-1-ylm ethyl)hydantoin, 14, the tetraphenylphosphonium salt of 7-(hydantoin-5 -ylmethyl)dodecahydro-7, 8-dicarba-nido-undecaborate, 15, 5-(o-carbora n-1-ylmethyl)-2-thiohydantoin, 16, and two new barbiturates, 5,5-bis(b ut-2-ynyl)barbiturate, 18, and -bis[(2-methyl-o-carboran-1-yl)methyl]b arbiturate, 20, are described. Hydantoins 14-16 were synthesized from o-carboranylalanine (Car, 13). The detailed syntheses of Car and two o ther carborane-containing amino acids, O-(o-carboran-1-ylmethyl)tyrosi ne (CBT, 5a) and p-(o-carboran-1-yl)phenylalanine (CBPA, 5b), presente d earlier as a communication,(16) are also described. Hydantoin 14 and barbiturates 18 and 20 were tested for their potential anticonvulsant activity. Initial qualitative screening showed moderate activities fo r hydantoin 14 and barbiturate 18. Barbiturate 20 had no activity. Com pound 14 appeared to be nontoxic at doses of 300 mg/kg (mice, ip) and 50 mg/kg (rats, oral). However, 18 was very toxic under similar condit ions.