Synthesis and Crystal Structure Determination of Methyl 2-acetyl-5′-phenyl-2H-spiro[benzo[d]isothiazole-3,3′-pyrazole]-1,1-dioxide-2′(4′H)-carboxylate and Methyl 2-acetyl-5′-(2-thienyl)-2H-spiro[benzo[d]isothiazole-3,3′-pyrazole]-1,1-dioxide-2′(4′H)-carboxylate

Dilithiated C(alpha), N-carbomethoxyhydrazones were condensed with lithiated methyl 2-(aminosulfonyl)benzoate to afford intermediates that were isolated and not characterized but cyclized with acetic anhydride, which also resulted in N-acetylation. The X-ray crystal structure determinations of methyl 2-acetyl-5'-phenyl-2H-spiro[benzo[d]isothiazole-3,3'-pyrazole]-1,1-dioxide-2'(4'H)-carboxylate and methyl 2-acetyl-5'-(2-thienyl)-2H-spiro[benzo [d]isothiazole-3,3'-pyrazole]-1,1-dioxide-2'(4'H)-carboxylate products were a follow up for absorption spectra, and they confirmed their structures. Mechanistic intermediates to describe the reaction may include C-acylated intermediates that cyclize to spiro(N-benzoisothiazole dioxide-pyrazole) instead of N-carbomethoxypyrazole-ortho-benzenesulfonamides. Crystals of C19H17N3O5S 7 are monoclinic, P2(1)/c, a = 11.899(2) angstrom, b = 17.562(4) angstrom, c = 9.484(2) angstrom, beta = 111.03(3)degrees, Z = 4, V = 1849.9(6) angstrom(3), R-1 = 0.0857 and wR(2) = 0.2216 for reflections with I > 2 sigma(I); crystals of C17H15N3O5S2 8 are orthorhombic, Pbca, a = 16.045(3) angstrom, b = 10.746(2) angstrom, c = 20.389(4) angstrom, Z = 8, V = 3516(1) angstrom(3), R-1 = 0.0841 and wR(2) = 0.2179 for all reflections with I sigma 2 sigma(I).