2,3,4,5,6,7-Hexahydro-9,10-dimethoxy-l,2-benzothiazonin-3-one 1,1-dioxide

The amide group in the nine-membered ring of the title compound, C13H17NO5S, has the trans conformation. The molecules are linked into infinite one-dimensional chains by bifurcated intermolecular N-H...O hydrogen bonds involving the amide O atom and one of the sulfonyl O atoms of the same neigh- bouring molecule. The compound was prepared by the Friedel-Crafts acylation of 1,2-dimethoxybenzene and glutaric acid anhydride, followed by reduction of the aryl ketone, esterification, chlorosulfonation, treatment with ammonia, saponification and cyclization of the corresponding 5-(2-sulfamoylphenyl)butanoic acid

10,10-Dimethyl-l,2,8-thiadiazecan-9-one 1,1-dioxide

The puckered ten-membered ring of the title compound, C9HI8N2O3S, contains a sulfonamide group and an amide moiety which has the trans conformation. The molecules are linked into infinite two-dimensional networks by intermolecular N-H...O hydrogen bonds involving both NH groups along with the amide O atom and one of the sulfonyl O atoms from different neighbouring molecules. The title compound was prepared by a ring-enlargement reaction of the corresponding N-aminoalkyl 1,2-thiazetidin-3-one 1,1-dioxide

Ring-enlargement and ring-opening reactions of 1,2-thiazetidin-3-one 1,1-dioxides with ammonia and primary amines as nucleophiles

The N-benzyl- and N-alkyl-substituted 1,2-thiazetidin-3-one 1,1-dioxides 1b - d reacted readily with NH3 and primary amines via ring opening. The reaction with NH3 proceeded at -78° to room temperature yielding ring-opened adducts via nucleophilic attack of NH3 at the sulfonyl group, whereas the reactions with amines at room temperature yielded products via attack at the carbonyl group. The N-unsubstituted analogue 1a, when reacted with benzylamine in refluxing EtOH, also gave a product of ring opening via nucleophilic attack at the carbonyl group of 1a. The transamidation-like reactions of the 2-(aminoalkyl)-1,2-thiazetidin-3-one 1,1-dioxides 19a - d proceeded via six-, seven-, and eight-membered intermediates, giving the ring-enlarged eight-, nine-, and ten-membered products 21 - 24 (Schemes 8 and 9), respectively, in 42 - 87% yields. The products resulted from the nucleophilic attack of the amino group of the side chain at the carbonyl C-atom. The structure of the eight-membered product 24 with an asymmetrically situated methyl substituent was established by X-ray crystallography

Some thoughts about the single crystal growth of small molecules

This highlight critically compares various techniques to grow single crystals when only a few milligrams are available of the compound of interest. The authors describe vapour diffusion, evaporation, cooling, and layering techniques, as well as crystallisation in gels. A table of successfully applied solvent/antisolvent combinations for initial screening is given. Additionally, a comprehensive table of 107 solvents with their boiling points, densities and dielectric constants helps to optimise the crystal growth