Diastereoselective synthesis of 3,4-dihydro-2H-pyran-4-carboxamides through an unusual regiospecific quasi-hydrolysis of a cyano group

Abstract

SummaryAn efficient diastereoselective approach for the synthesis of functionalized 3,4-dihydro-2H-pyran-4-carboxamides with variable frame was developed based on the reaction of available 4-oxoalkane-1,1,2,2-tetracarbonitriles (adducts of TCNE and ketones) with aldehydes in an acidic media. An unusual process of quasi hydrolysis of the cyano group was observed in the course of the described regio- and diastereoselective transformation.

Synthesis of the first 4-oxobutane-1,1,2,2-tetracarbonitriles containing a phenol fragment and their transformation into cyano-substituted pyrrol-2-ones showing three-position molecular switching

“…One of the well-known DOS platforms is tetracyanoethylene adducts with ketones, namely 4-oxoalkane-1,1,2,2-tetracarbonitriles (OTCs) 24–40 (Fig. 1).…”

“…1). Due to the presence of the combination of a carbonyl group and four cyano groups on a four-carbon skeleton, OTCs are highly reactive compounds that can be transformed into furan derivatives, 24 various pyrroles, 25–29 pyridines, 30–32 and pyrans, 33 as well as into fused, 34 bicyclic 35 and spiro 36,37 heterocycles under the action of various reagents. In total, more than twenty directions of OTC transformations have been described in the literature.…”

Molecular diversity of the base-promoted reaction of phenacylmalononitriles with dialkyl but-2-ynedioates

“…Phenacylmalononitrile is one of the privileged functionalized compounds [1][2][3][4][5], because it contains one carbonyl group, two cyano groups, and an activated methylene unit. Phenacylmalononitrile exhibits versatile reactivity, high synthetic efficiency and molecular diversity and has been widely employed in many synthetic reactions [6][7][8][9][10]. On the other hand, phenacylmalononitrile is also a readily available substrate, which can be easily prepared through a base-promoted substitution reaction of phenacyl bromide with malononitrile under mild conditions [11][12][13][14][15][16].…”

Selective synthesis of multifunctionalized cyclopent-3-ene-1-carboxamides and 2-oxabicyclo[2.2.1]heptane derivatives

“…5 d Phenacylmalononitrile contains one carbonyl group, two cyano groups and an activated methylene unit, and therefore it exhibits versatile reactivity and has been widely employed in many synthetic reactions. 6,7 Additionally, phenacylmalononitrile can be conveniently obtained by a base promoted substitution reaction of phenacyl bromide with malononitrile in mild conditions. 8 In some reactions, phenacylmalononitriles could be in situ generated by directly employing phenacyl bromide and malononitrile in the reaction.…”