María M. Blanco

Simple and Efficient Microwave Assisted N-Alkylation of Isatin

We present herein the results of microwave promoted N-alkylations of isatin (1) with different alkyl, benzyl and functionalized alkyl halides. Reactions were carried out under different conditions, always employing methodologies compatible with MW assisted chemistry. Generation of isatin anion employing diverse bases and solvents or using the preformed isatin sodium salt was tested. The best results were achieved using K2CO3 or Cs2CO3 and a few drops of N,N-dimethylformamide or N-methyl-2-pyrrolidinone. These reactions present noteworthy advantages over those carried out employing conventional heating.

Improved Synthesis of N-Substituted 2,3-Pyridinedicarboximides with Microwave Irradiation

The microwave-induced synthesis of N-substituted 2,3-pyridinedicarboximides (1) by means of two different approaches is presented. One involves direct N-alkylation of quinolinimide (2) (Method A) and the other, dehydrative condensation of quinolinic anhydride (4) and amines (Method B). Reactions resulted highly accelerated, with improved yields in relation to those obtained by conventional heating. The scope and limitations of each method and its variants are discussed.

A NEW SYNTHETIC APPROACH TO N,N′-DISUBSTITUTED 1,n-ALKANEDIAMINES

A general procedure is described for the synthesis of unsymmetrically substituted N-aryl-N′-alky1 (or aryl) 1,n-alkanediamines 1 (n = 2−5) by reduction of ω-alkyl (or aryl) aminoalkanamides 2 with borane. Compounds 2 are easily obtained by aminolysis of the corresponding ω-haloalkanamides 3.

Improved Synthesis of N-Substituted Quinolinimides Using Microwave Irradiation

The synthesis of several quinolinimidoacetic acid derivatives (I) by two different routes, starting from quinolinic anhydride or quinolinimide, is described. In all cases better yields and decreased reaction times were achieved employing microwave irradiation as an alternative source of energy.

Autooxidation and rearrangement reactions of isoquinolinone derivatives

4-Hydroxy-2-methyl-1-oxo-1,2-dihydroisoquinoline-3-carboxylic acid derivatives 1 in solution afford a mixture of the dealkoxycarbonylated product 2 and 4-hydroxy-2-methyl-1,3-dioxo1,2,3,4-tetrahydroisoquinoline-4-carboxylic acid derivatives 3. Reactions 1→3 involve compounds 1 tautomerization, C-3 hydroxylation and final α-ketol type rearrangement. The synthetic utility of this transformation was explored.

MASS SPECTROMETRY OF AROMATIC CYCLIC IMIDES AND AMIDES. PART I: ELECTRON IONIZATION INDUCED DECOMPOSITION OF N-SUBSTITUTED 2,3-PYRIDINE-DICARBOXIMIDES

The behaviour of a series of N-substituted 2,3-pyridinedicarboximides (1-14) under electron impact mass spectrometry at 70eV is analyzed. Compounds under study were divided into three groups according to their substitution patterns, namely N-aryl, N-alkyl and N-functionalized alkyl derivatives, which in turn determine the dominant fragmentations. The proposed fragmentation patterns are supported by high resolution, B/E and B 2 /E linked-scan mass spectrometric data of some selected compounds. Results are compared in some cases to data reported for the related phthalimides.

Una Nueva Propuesta Didáctica para la Enseñanza Universitaria de Química Orgánica

The study discusses the reformulation of problem activities in classes and laboratory work in basic organic chemistry courses and of the printed materials use in these courses. The objective of these reformulations was to awaken student interest and participation in scientific and professional activities. As an example, a section of the Guide to Problems and Laboratory Activities corresponding to the unit Organic Synthesis is presented. Observations are made on both types of classes, in which work was done with traditional didactic methods. Analysis of the observations suggested that the majority of students became actively involved with the new proposal. It is concluded that the proposed activities improved the motivation of the students, stimulated consultation and study texts, and favored the application of the conceptual contents to real problems situations.