A single-step synthesis route is described for the preparation of a metal-polymer composite in which palladium acetate and meta-amino benzoic acid were used as the precursors for palladium nanoparticles and poly(meta-amino benzoic acid) (PABA). The palladium nanoparticles were found to be uniformly dispersed and highly stabilized throughout the macromolecule matrix. The resultant composite material was characterized by means of different techniques, such as IR and Raman spectroscopy, which provided information regarding the chemical structure of the polymer, whereas electron microscopy images yielded information regarding the morphology of the composite material and the distribution of the metal particles in the composite material. The composite material was used as a catalyst for the ethylene hydrogenation reaction and showed catalytic activity at higher temperatures. TEM studies confirmed the changed environment of the nanoparticles at these temperatures.

A wide range of N-(ethoxycarbonylmethyl)enaminones, prepared by the Eschenmoser sulfide contraction between N-(ethoxycarbonylmethyl)pyrrolidine-2-thione and various bromomethyl aryl and heteroaryl ketones, underwent cyclization in the presence of silica gel to give ethyl 6-(hetero)aryl-2,3-dihydro-1H-pyrrolizine-5-carboxylates within minutes upon microwave heating in xylene at 150 °C. Instead of functioning as a nucleophile, the enaminone acted as an electrophile at its carbonyl group during the cyclization. Yields of the bicyclic products were generally above 75%. The analogous microwave-assisted reaction to produce ethyl 2-aryl-5,6,7,8-tetrahydroindolizine-3-carboxylates from (E)-ethyl 2-[2-(2-oxo-2-arylethylidene)piperidin-1-yl]acetates failed in nonpolar solvents, but occurred in ethanol at lower temperature and microwave power, although requiring much longer time. A possible mechanism for the cyclization is presented, and further functionalization of the newly created pyrrole ring in the dihydropyrrolizine core is described.

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The mol­ecular structure of the title compound, C10H12O4, contains an intra­molecular hydrogen bond between the phenol and acetyl substituents. In the crystal, C—H⋯π inter­actions act between the mol­ecules in a cyclic manner to stabilize stacks of mol­ecules along the b axis. Several C—H⋯O inter­actions are present between the stacks.

The title compound, C(20)H(19)NO(5)S(2), crystallizes as an almost 2:1 mixture of two molecular orientations (described as Orient-A and Orient-B). The consequences of these two orientations is the formation of three types of N-H...O hydrogen-bonded dimers in which the (Orient-A + Orient-A) dimers are likely to be the most stable, while the mixed (Orient-A + Orient-B) dimers are more frequent. Extra interactions in the form of C-H...O and C-H...pi interactions act to further stabilize these dimers and probably allow the less energetically favourable (Orient-A + Orient-B) and (Orient-B + Orient-B) hydrogen-bonded dimers to exist by preventing their conversion to (Orient-A + Orient-A)-only hydrogen-bonded dimers during the crystal-growth process.