Selective β-oxidation of α-sulfanyl amides

Stereoselective Synthesis of 2-Thio-3-Chloroacrylamides and Investigation of their Reactivity

“…11 An important synthetic outcome is transformation to the b-aldehyde in either its free or acetal form. 11,20 The Diels-Alder cycloadditions of a range of 2-thio-3-chloroacrylamides to cyclopentadiene and 2,3-dimethyl-1,3-butadiene under thermal, catalytic, and microwave conditions have also been studied, with the stereoselectivity and reaction efficiency dependent upon the reaction conditions. While the cycloadditions have been attempted at the sulfide, sulfoxide, and sulfone levels of oxidation, use of the sulfoxide derivatives is clearly beneficial for stereoselective construction of Diels-Alder cycloadducts.…”

“…This simple, rapid procedure involving only filtration, evaporation, and extraction gave a very clean product within a total reaction time of typically 2.5 hours in 17-88% yield over three steps, without intermediate isolation (Scheme 26). 20 Thus, the telescoped transformation of a-thioamides to the corresponding b-hydroxypropanamides, without intermediate isolation, proceeds under mild conditions without the use of metal catalysis, in yields of up to 88% and typically in a very short time (ca. 2.5 hours) for the three-step process.…”

“…An important synthetic outcome from the investigation of the reactivity of the b-chloroacrylamides as Michael acceptors is the transformation of the a-thioamides via the b-chloroacrylamides to the b-aldehyde, in either its free or acetal form (Scheme 35).Thus, the unactivated methyl group is selectively transformed to the aldehyde or acetal in a convenient multistep sequence, some of which can be telescoped into a single-pot process. 11,20 Scheme 35…”