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[摘要]：Using inexpensive, readily available starting materials, a trisubstituted hydrazine was synthesized by our recently developed techniques and converted to the corresponding tosylcarbamoyl derivative (N-tosylsemicarbazide) which can be further alkylated on its carbamoyl nitrogen under Mitsunobu conditions to give compounds of type 6. The yields in all steps are high. Similarly, selectively protected, N,N'-substituted hydrazines can be tosylcarbamoylated twice with intermediary alkylation to give dimeric ureas 11 with four different substituents in addition to the tosyl groups. The latter can in principle be replaced by other sulfonyl groups of higher pharmaceutical interest, thus allowing simultaneous variation of 5 sites in 6 or 6 such in 11. Due to the importance of ureas and sulfonylureas as pharmaceuticals, these new flexible synthetic schemes might therefore be applicable in the search for new lead substances by combinatorial chemistry. In connection with this work an unprecedented N-benzyl cleavage by trifluoroacetic acid of potential practical interest was discovered. |
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