Current Organic Chemistry - Volume 11, Issue 10, 2007

1,4-Dihydropyridines are of great chemical and pharmacological significance as evidenced from a chapter written by Drs Reddy and Chakravarty form Dr Reddy's Laboratories Ltd, Hyderabad, India. It is well-known that carbon nucleophiles are useful in organic synthesis in general and in heterocyclic synthesis in particular. In the final comprehensive chapter Professors Madkour and Elgazwy from Ain Shams University, Cairo, Egypt discusses new developments in this field.

1,4-Dihydropyridines are excellent precursors of various pharmacologically important molecules which possess calcium channel blocking activity. The synthesis of various 1,4-dihydro pyridines and their importance is reviewed for the first time to our knowledge.

New developments in the utilities of some carbon nucleophiles in heterocyclic synthesis are reviewed. General synthetic routes based on the utilization of carbon nucleophiles of active methylene are discussed. The major methods and modifications are analyzed. Heterocycles are ubiquitous in all kind of compounds of interest, and among all the possible synthetic methods of achieving their introduction into a structure, probably the use of a carbon nucleophile analogues are the most direct one. The present review deals with the generation and synthetic of carbon nucleophile, which uses as scaffold for the heterocyclic synthesis, and can be considered as an update review. Therefore the only references published upon the second quarter of 2003 are included, and the same restrictions to the literature coverage apply.

As the well-known soft ionization techniques, matrix assisted laser desorption/ionization (MALDI) - time of flight (TOF) mass spectrometry and electrospray ionization (ESI) MS are widely used in the investigative field of macromolecules including biomolecules and synthetic polymers since they were introduced in the late 1980s. Herein, emphasis is put on the application of MALDI-TOF MS and ESI MS on synthetic polymers by reviewing the literature in recent two decades. The applications to the characterization of synthetic polymers covering determination of molecular weight, structure analysis and quantitation by MALDI-TOF are reviewed. The combination with other analytic methods such as size exclusion chromatography (SEC) opened a new gate for the characterization of broad polydispersed polymers. The applications on different classes of synthetic polymers indicate that MALDI-TOF MS is ideal tools for the characterization of synthetic polymers.

The acid-catalyzed alkene-aldehyde condensation, known as the Prins reaction, is reviewed. Lewis acids, organic acids and supported catalysts have been reported to assist both the Prins acyclic reaction and the Prins cyclization. Acetals and oxocarbenium ions (generated from aldehydes and alcohols) have been described as reacting systems in the Prins reaction. Prins cyclizations have been used to form mainly five- and six-membered rings, albeit formation of seven to nine rings have been described. The Prins reaction (and cyclization) has been developed as a key strategic element in the total synthesis of different natural products.