We have compiled and reviewed the recent literature about “Enantioselective Organocatalyzed Synthesis of 2-Amino-3-cyano-4H-chromene Derivatives” and the resulting article has been just published in Symmetry in the frame of its Special Issue dedicated to “Asymmetric Organocatalysis”.
Isaac G. Sonsona, Eugenia Marqués-López and Raquel P. Herrera. Symmetry 2015, 7(3), 1519-1535; doi:10.3390/sym7031519
Congratulations guys for the well done job!
Abstract: The structural motif that results from the fusion of a benzene ring to a heterocyclic pyran ring, known as chromene, is broadly found in nature and it has been reported to be associated with a wide range of biological activity. Moreover, asymmetric organocatalysis is a discipline in expansion that is already recognized as a well-established tool for obtaining enantiomerically enriched compounds. This review covers the particular case of the asymmetric synthesis of 2-amino-3-cyano-4H-chromenes using organocatalysis. Herein, we show the most illustrative examples of the methods developed by diverse research groups, following a classification based on these five different approaches: (1) addition of naphthol compounds to substituted α,α-dicyanoolefins; (2) addition of malononitrile to substituted o-vinylphenols; (3) addition of malononitrile to N-protected o-iminophenols; (4) Michael addition of nucleophiles to 2-iminochromene derivatives; and (5) organocatalyzed formal [4+2] cycloaddition reaction. In most cases, chiral thioureas have been found to be effective catalysts to promote the synthetic processes, and generally a bifunctional mode of action has been envisioned for them. In addition, squaramides and cinchona derivatives have been occasionally used as suitable catalysts for the substrates activation.
Keywords: chromene; benzopyran; 2-amino-3-cyano-4H-chromene; malononitrile; enantioselective; organocatalysis; synthesis; thiourea; squaramide; cinchona derivatives