Synthesis and reactions of enantiomerically pure dialkyl diselenides from the p-menthane group

A convenient route for the synthesis of optically active dialkyl diselenides from the p-menthane system utilizing a reaction of alkyl tosylates and chlorides with sodium diselenide is reported. The diselenides obtained have been used for asymmetric methoxyselenenylation of styrene. Quantum chemical calculations of the chair conformers stability of the terpeneselenenyl bromides from the p-menthane group have also been carried out using density functional theory (DFT, at the B3LYP/6-311G(d) level). The influence of the diselenides structure on the stereoselectivity in the methoxyselenenylation reaction is also discussed.

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(+)-Dineomenthyl diselenideC20H38Se2Ee = 99%[α]D20=+302.2 (c 5.58, CHCl3)Source of chirality: (−)-mentholAbsolute configuration: (1S,2S,5R,1′S,2′S,5′R)

(−)-Dineocarvomenthyl diselenideC20H38Se2Ee ⩾ 98%[α]D20=-195.5 (c 3.36, CHCl3)Source of chirality: (+)-carvoneAbsolute configuration: (1R,2S,5S,1′R,2′S,5′S)

(+)-Dicarvomenthyl diselenideC20H38Se2Ee ⩾ 98%[α]D20=+256.7 (c 0.60, CHCl3)Source of chirality: (+)-carvoneAbsolute configuration: (1S,2S,5S,1′S,2′S,5′S)

(+)-Dineoisocarvomenthyl diselenideC20H38Se2Ee ⩾ 98%[α]D25=+80.4 (c 0.95, CHCl3)Source of chirality: (+)-carvoneAbsolute configuration: (1S,2R,5S,1′S,2′R,5′S)

(−)-Diisocarvomenthyl diselenideC20H38Se2Ee ⩾ 98%[α]D20=-66.6 (c 10.64, CHCl3)Source of chirality: (+)-carvoneAbsolute configuration: (1R,2R,5S,1′S,2′R,5′S)

(−)-Dimenthyl diselenideC20H38Se2Ee = 99%[α]D20=-306.3 (c 5.10, CHCl3)Source of chirality: (−)-mentholAbsolute configuration: (1R,2S,5R,1′R,2′S,5′R)

(−)-Dineoisomenthyl diselenideC20H38Se2Ee >98%[α]D25=-232.5 (c 6.70, CHCl3)Source of chirality: (+)-isomentholAbsolute configuration: (1R,2R,5R,1′R,2′R,5′R)

(+)-Diisomenthyl diselenideC20H38Se2Ee >98%[α]D22=+27.6 (c 0.90, CHCl3)Source of chirality: (+)-isomentholAbsolute configuration: (1S,2R,5R,1′S,2′R,5′R)