The iodine-assisted hydroxyselenenylation of alkenes with elemental selenium

Iodine-Mediated Alkoxyselenylation of Alkenes and Dienes with Elemental Selenium

A one-pot synthesis of linear and cyclic β-alkoxyselenides is developed through the iodine-mediated three-component reaction of elemental selenium with alkenes (dienes) and alcohols. Selenylation of 1,5-hexadiene gives 2,5-di(methoxymethyl)tetrahydroselenophene and 2-methoxy-6-(methoxymethyl)tetrahydro-2H-selenopyran via the 5-exo-trig and 6-endo-trig cyclization. 1,7-Octadiene affords only linear 1:2 adduct with two terminal double bonds. 1,5-Cyclooctadiene results in one diastereomer of 2,6-dialkoxy-9-selenabicyclo [3.3.1]nonanes via 6-exo-trig cyclization. With 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane, the first ring-substituted representative of a very rare class of heterocycles, 1,4,2,6-oxaselenadisilinanes, was obtained at a high yield.

A low-temperature dynamic 1 H, 13 C, and 77 Se NMR study of 2,2'-selenodicyclohexanol

2,2'-Selenodicyclohexanol 1 was shown to exist as two (all-trans-achiral and all-trans-chiral) stereoisomers with all C-Se and C-OH bonds in equatorial orientations. When the temperature is lowered, the ¹ H, ¹³ C, and ⁷⁷ Se NMR spectra exhibit a strongly one-sided dynamic process, which involves sterically hindered rotation about the C-Se bond. Structures, free energy differences of the rotamers ΔG°, and the rotational barrier were determined and confirmed by quantum chemical calculations at the M06-2X/6-311++G**, M06-2X/cc-pVTZ, and MP2/6-311+G** levels of theory.