A 2D lamellar metal-organic coordination polymer [2-（1,3）-dithian-2-ylidene malonate] diaquoicadmium（Ⅱ） hydrate, [Cd（dym）（H2O）2（H2O）], （dym = 2-（1,3）-dithian-2-ylidene malonate）, has been prepared by conventional solution reaction. The structure analysis suggests that the polymer crystallized in orthorhombic system with space group Pbca and the final R indices （I 〉2σ（I））： R1 = 0.0236 and wR2= 0.0738. Crystal data： a = 12.6138（5）, b = 8.4528（3）, c = 22.5867（8） A°, V = 2409.8（15）A°^3, Z = 3, F（000） = 1520, Dc = 1.482 g/cm^3,μ（MoKα） = 0.990 mm^-1 and Mr= 384.69 g/mol. The Cd（Ⅱ） ion is in a disordered triangle prism environment. The Cd-O distances are in the range of 2.2643（14）-2.3641（15）A°. In the crystal, the Cd atoms are arranged at the comers of honeycomb-like hexagonal 24-membered macrometallacycle. There is a weak C-H...S interaction between the 1,3-dithiocyclohexyl groups of two adjacent dym ligands.
a-Oxo ketene dithioacetals, methyl 2-（1,3-dithian/dithiolan-2-ylidene）-3-oxobutanoate （2a/2b） prepared in nearly quantitative yields simply from methyl acetylacetate, carbon disulfide and 1,3-dibromopropane/1,2-dibromoethane in the presence of potassium carbonate, were investigated in the thioacetalization with various carbonyl compounds 3. It has been demonstrated that methyl 2-（1,3-dithian-2-ylidene）-3-oxobutanoate （2a） could act as a nonthiolic, odorless and practical thioacetalization reagent. A range of aldehydes and ketones 3 were converted into the corresponding dithioacetals 4 in high yields （up to 91%） in the presence of 2a. Moreover, 2a showed high chemoselectivity between aldehyde and ketone in thioacetalization.
