Asymmetric enamine catalysis.

Microwave assisted organic reactions

Tetrazole and acylsulfonamide organocatalysts derived from proline have been synthesised and applied to the asymmetric Mannich, nitro-Michael and aldol reactions to give results that are superior to the proline-catalysed counterpart.

Organocatalysis with proline derivatives: improved catalysts for the asymmetric Mannich, nitro-Michael and aldol reactions

Applications of microwave energy in organic chemistry. a review

This report describes the unprecedented use of unmodified aldehydes as donors in a catalytic asymmetric Mannich-type reaction. The proline-catalyzed reaction of N-PMP-protected α-imino ethyl glyoxylate with unmodified aliphatic aldehydes provided a general and very mild entry to either enantiomer of β-amino and α-amino acids and derivatives in high yield and stereoselectivity. Six of the seven aldehydes studied yielded products with ee values of 99% or greater. The diastereoselectivity of the reaction increased with the bulkiness of the substituents of the aldehyde donor in the order R = Me < Et < i-Pr < n-Pent. In five of the cases studied, excellent syn stereoselectivities were achieved. In addition, the corresponding chiral β-amino aldehyde adducts can be readily converted to the corresponding amino acid derivatives. Most significantly, this approach provides facile access to substituted β-lactams.

A Highly Enantioselective Route to Either Enantiomer of Both α- and β-Amino Acid Derivatives

Microwave-induced organic reaction enhancement chemistry. 2. Simplified techniques

Efficient synthesis of a wide variety of heterocycles on 0.1 to 200 g scale was conducted in organic solvents in a commercial microwave oven in a few minutes at a low energy level. Erlenmeyer flasks were adequate reaction vessels since neither high pressure nor high temperature were involved. Fast monitoring of synthetic reactions was achieved by tlc separation and transfer of tlc spot material directly to a solids probe of a chemical ionization mass spectrometer. Microwave oven-induced reaction enhancement (MORE) chemistry is not due to thermolysis: one reaction was conducted successfully in a reaction vial encased in a block of ice.

Highly Accelerated Reactions in a Microwave Ovem: Synthesis of Heterocycles

Stereocontrolled synthesis of α-vinyl β-lactams and their transformation to convenient intermediates for PS-5, PS-6, asparenomycin, and thienamycin are described

Studies on lactams. Part 84. .beta.-Lactams via .alpha.,.beta.-unsaturated acid chlorides: intermediates for carbapenem antibiotics

Polyamideimides have long been known for their excellent heat resistance properties. This paper will report the synthesis of two new polyamideimides from 4,4′-bis-(3-carboxylphthalimidyl)biphenyl and/or 4,4′-bis-(3-chlorocarbonylphthalimidyl)biphenyl and two aromatic diamines by using solution polycondensation reaction at low temperature in polar organic solvents. The optimum conditions necessary for the polycondensation reaction have been studied. Characterization of polymers is done by elemental analysis, IR data, and viscosity measurements. The prepared polymers are partially soluble in electron donating organic solvents for example dimethyl formamide, dimethyl acetamide, m-cresol etc. In addition to heat resistance properties of polymers, chemical stability towards acid and base and moisture absorption properties have been evaluated.



Polyamidimide sind seit langem fur ihre ausgezeichnete Warmebestandigkeit bekannt. Es wird uber eine Synthese von zwei neuen Polyamidimiden aus 4,4′-bis-(3-Carboxylphthalimidyl)biphenyl bzw. 4,4′-bis-(3-Chlorcarbonylphthalimidyl)biphenyl und zwei aromatischen Diaminen durch Losungskondensation bei niedrigen Temperaturen in polaren organischen Losungsmitteln berichtet. Die optimalen Bedingungen fur die Polykondensation wurden untersucht. Die Charakterisierung der Polymeren erfolgte durch Elementaranalyse, IR-Spektroskopie und Viskositatsmessungen. Die hergestellten Polymeren sind teilweise loslich in elektronenspendenden organischen Losungsmitteln wie z. B. Dimethylformamid, Dimethylacetamid, m-Kresol usw. Zusatzlich zur Warmebestandigkeit wurde auch die Resistenz gegen Sauren und Basen sowie die Feuchtigkeitsabsorption bestimmt.

Malay Ghosh

Papers

Microwave-induced organic reaction enhancement chemistry. 2. Simplified techniques

Highly Accelerated Reactions in a Microwave Ovem: Synthesis of Heterocycles

Studies on lactams. Part 84. .beta.-Lactams via .alpha.,.beta.-unsaturated acid chlorides: intermediates for carbapenem antibiotics

Heat resistant polyamideimides, 3. Synthesis, characterization, and evaluation of thermal and other properties†

Microwave-Induced Organic Reaction Enhancement Chemistry. Part 2. Simplified Techniques.