Synthesis and Selective Functionalization of Thiadiazine 1,1-Dioxides with Efficacy in a Model of Huntington's Disease

The scope of the acid-mediated 3-component synthesis of thiadiazines was investigated. A selective functionalization of the six-membered heterocyclic core structure was accomplished by sequential alkylations, saponifications, and coupling reactions. Several new analogs of a dihydropyrimidinone Hsp70 chaperone agonist, MAL1-271, showed promising activity in a cell based model of Huntington's disease.

N,N-Dialkyl-N′-Chlorosulfonyl Chloroformamidines in Heterocyclic Synthesis. Part XII. Synthesis and Reactivity of the Pyrazolo[3,4-e][1,2,4]thiadiazine Ring System

N,N-Dialkyl-N′-chlorosulfonyl chloroformamidines 1 reacted regioselectively with 1-substituted 5-aminopyrazoles 2 via a 1,3-CCN dinucleophilic substitution to afford pyrazolo[3,4-e][1,2,4]thiadiazines 3 as the sole isolated products. Compounds 3, representatives of a very rare ring system, were shown to possess three nucleophilic sites at N2, N4, and N6. Methylation occurred at all three sites. Alkylation with benzylic halides occurred preferentially at N2, but some also occurred at N4, and at C7a. Alkylation with ethyl bromoacetate occurred at both N4 and N6, but the latter derivatives underwent a pyrazole ring expansion to afford pyrimido[4,5-e][1,2,4]thiadiazine derivatives. Compounds 3 were unreactive towards various acylating agents.

3-Amino-4-[4-(dimethyl-amino)-phen-yl]-4,5-dihydro-1,2,5-thia-diazole 1,1-dioxide

The title compound, C(10)H(14)N(4)O(2)S, exists in the amine tautomeric form. The dihedral angle between the benzene and thia-diazo-lidine rings is 66.54 (19)°. In the crystal, mol-ecules are linked by N-H⋯O and N-H⋯N hydrogen bonds into a layer parallel to the ac plane. The layers are further linked by C-H⋯O hydrogen bonds.