Cycloadditions of aldehydes with carbonyl ylides to give dioxolanes have been carried out without solvent under microwave irradiation. The reactions proceeded in similar yields and stereoselectivities, but in shorter reaction times, than those obtained in toluene at reflux using an oil bath. Cycloadditions conducted between imines and carbonyl ylides using the same protocol were less efficient because the oxazolidines formed proved unstable under the reaction conditions.

The synthesis of new 3-substituted cournarins appended to imidazolium, pyridinium, 3-dimethylamino pyridinium, 3-chloro pyridinium and 3-bromo pyridinium salts is reported. These salts were prepared by tandem reactions, followed by quantitative anionic metathesis. The structure of these new 3-substituted coumarins was established by NMR (H-1, C-13) and high-resolution mass spectrometry.

We report here a synthesis of a new rhodacyanines 7X analogous to MKT-077 with quantitative yield using as starting material the thiazolinethione 1. Merocyanines 4 and their tosylates 5 have been prepared as intermediates for this class of compounds. The reactions leading to rhodacyanine 7X have been studied under microwave irradiation.

We have previously reported a new synthesis of amides from esters and amines under microwave irradiation, offering much higher yields than those achieved with conventional heating [1]. We have now extended these studies to the ring closure of neat iminoesters I2, I3 and I4-I6 to give five- and six-membered ring lactams L5, L6 and larger lactams L7-L9 (where I means imine and L means lactam), respectively, under both classical heating conditions and microwave irradiation.

A rapid and easy solvent free one-pot synthesis of 5-arylidene-2-imino-4- thiazolidinones by condensation of the thioureas with chloroacetic acid and an aldehyde under microwave-irradiation is described.

Neat non-volatile amines react with various aromatic aldehydes in the absence of any catalyst, solid support, or solvent, to give imines after a reaction time of eight minutes under microwave irradiation by a clean and very efficient process (yields: 75 - 100%). In the case of volatile amine, methylamine, 1,3-dimethylurea dispersed on montmorillonite K 10 is used as an amine precursor to prepare the corresponding imines.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

New nitrocyclohexanols 3a-f are synthesized by a clean and original method from nitromethane 1 and unsaturated ketones 2a-f in the presence of solid potassium fluoride-alumina under solvent-free conditions coupled with microwave irradiation. The reaction involves a double and diastereoselective Michael addition followed by ring closure. Another diastereomer 3', which differs by the configuration of C-4, is obtained in the presence of piperidine and EtOH at room temperature. (C) 2003 Elsevier Ltd. All rights reserved.

ABSTRACT Formamide, primary and secondary amines react with esters in the presence of potassium tert-butoxide under microwave irradiation. Substituted amides are formed in yields (generally more than 70%) much higher than under conventional heating.

AbstractFor Abstract see ChemInform Abstract in Full Text.

ABSTRACT Growth inhibition of Lactococcus lactis provoked by increasing osmolarity is reversed when glycine betaine (GB) or its analogs are added to a defined medium. Lacticin 481 production increased sharply with growth medium osmolarity in the absence of osmoprotectant but remained unaffected when GB was supplied in media of increasing osmolarity.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ABSTRACT An extract from the marine alga Ulva lactuca was highly osmoprotective in salt-stressed cultures of Sinorhizobium meliloti 102F34. This beneficial activity was due to algal 3-dimethylsulfoniopropionate (DMSP), which was accumulated as a dominant compatible solute and strongly reduced the accumulation of endogenous osmolytes in stressed cells. Synthetic DMSP also acted as a powerful osmoprotectant and was accumulated as a nonmetabolizable cytosolic osmolyte (up to a concentration of 1,400 nmol/mg of protein) throughout the growth cycles of the stressed cultures. In contrast, 2-dimethylsulfonioacetate (DMSA), the sulfonium analog of the universal osmoprotectant glycine betaine (GB), was highly toxic to unstressed cells and was not osmoprotective in stressed cells of wild-type strains of S. meliloti . Nonetheless, the transport and accumulation of DMSA, like the transport and accumulation of DMSP and GB, were osmoregulated and increased fourfold in stressed cells of strain 102F34. Strikingly, DMSA was not toxic and became highly osmoprotective in mutants that are impaired in their ability to demethylate GB and DMSA. Furthermore, 2-methylthioacetate and thioglycolic acid (TGA), the demethylation products of DMSA, were excreted, apparently as a mechanism of cellular detoxification. Also, exogenous TGA and DMSA displayed similar inhibitory effects in strain 102F34. Thus, on the basis of these findings and other physiological and biochemical evidence, we infer that the toxicity of DMSA in wild-type strains of S. meliloti stems from its catabolism via the GB demethylation pathway. This is the first report describing the toxicity of DMSA in any organism and a metabolically stable osmoprotectant (DMSP) in S. meliloti.

Ketones and formamides are formed by cleavage of β,β-disubstituted enamines over KMnO4Al2O3 without solvent under microwave irradiation. The comparison was made between, domestic oven, focused oven and classical heating.

2-Substituted (1 H )-perimidine 1 reacts with various 2-chloroacyl chlorides 3 to afford new ethyl 2-oxo-Δ 2. pyrrolino-[1,2-a]-(4 H )-perimidine-3-carboxylates 5 in good yields by a N,C-cyclocondensation reaction sequence. The 1 H, 13 C NMR spectrum of some representative compounds are discussed. The reactions of 1 with trans -cinnamoyl chloride 6 and with 3-chloropropanoyl chloride 8 as β-dielectrophiles have been investigated and gave directly the corresponding fused perimidines 7 with reverse regiochemistry.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Imidates derived from alpha-amino esters, undergo cycloaddition reactions as stabilized ylides, with imines in good yields.

Total contents of aromatic choline esters and sinapine have been investigated in seeds of cruciferous species belonging to Arabis, Brassica, Cakile, Diplotaxs, Eruca, Hesperis, Matthiola, Raphanobrassica, Raphanus and Sïnapis. Choline esters such as sinapine, isoferuloylcholine, feruloylcholine, hesperaline and 4-hydroxybenzoylcholine, have been found in many of the plants under study. Qualitative and quantitative distribution patterns of these compounds are genus-characteristic. This suggests them to be a useful tool in the chemotaxonomy of Crucifereae. In spite of their genus-specific distribution pattern, the capacity of plants to accumulate and store phenolic choline esters in seeds is highly variable within the genus Brassica. Besides a genetic control, the aromatic choline esters content is also influenced by environmental conditions. Brassica species with high and low chromosome numbers were compared according to their qualitative and quantitative aromatic choline ester content. Genomic divergence or affinity among the species under study are discussed.