The Chemistry of Alkenyl Nitriles and its Utility in Heterocyclic Synthesis

Abstract

including purines [7,8], pyrimidines [9], pyrazines [10] (some which are widely employed in the fluorescent dye industry [11]), imidazoles [12], biphenylenes [13], porphyrazines (which have great potential in optical sensor technology) [14] and diimines that are used as catalysts [15]. This review highlights the alkenyl nitrile chemistry with the focus on the utility of heterocyclic compounds. The synthesis and chemistry of the highly strained aryl nitrile is also briefly reviewed [16]. Heterocycles are ubiquitous in all kind of compounds of interest, and among all the possible synthetic methods of achieving their introduction into an structure, probably the use of a alkenyl nitrile analogue is the most direct one. The present review deals with the generation and synthetic uses of alkenyl nitriles and aryl nitriles formed in heterocyclic synthesis, and can be considered as an update of our revision published in 2007 on this topical [17]. Therefore, only references published from the second quarter of 2003 until the third quarter of 2010 are included, and the same restrictions to the literature coverage applied. Thus, only heterocycles compounds which are found applicability are considered. As previously, the present review is organized by the type of ring members and subdivided by the type of heterocycles fused compounds, including methods for their preparation and their synthetic uses. New developments in the utilities of some alkenyl nitriles in heterocyclic synthesis are reviewed. General synthetic routes based on the utilization of alkenyl nitriles of active imines are discussed. The major methods and modifications are analyzed [18-21]. In this review, which covers the literature up to date, we describe the new and improved methods for the construction of the skeletons, with a particular emphasis on the four, five and six membered ring of heterocyclic compounds. Some of these procedures have clear technical advantages over older methods in terms of yield and versatility, but do not employ new chemistry in the construction of the ring systems. The