Stereoselective hydrogenation of 3-acyl-substituted 2- (trifluoromethyl)-2H-chromen-5-one and chromane scaffolds in NaBH4 /ethanol medium

Abstract

Octahydrochromens are compounds that contain a non-aromatic cyclic ether nucleus of tetrahydropyran, which are part of a wide array of natural compounds, as well as synthetic flavors substances. For this reason, there is a clear growth in the employing of some of them as flavor and perfume compounds in certain odorants. On the other hand, the reducing agent sodium borohydride is commonly used for reduction of unsaturated carbonyl compounds, is becoming a standard method in both academic and industrial laboratories. In this context, we describe a synthesis of a new series of substituted octahydrochromenone derivatives (2) from the 2-trifluoromethyl-2Hchromenones (1) and one example of 3,4-dihydro2H-chromane (4) from the respective 2(trifluoromethyl)chromane (3), employing sodium borohydride/ethanol as an efficient, straightforward and selective reductive reaction medium for these types of heterocyclic compounds.