The Use of Sulfides Derived from Carane, P-Menthane, Pinane, and Bornane in the Synthesis of Optically Active Epoxides

Abstract

Convenient routes for the synthesis of optically active methyl, phenyl, and dimonoterpenyl sulfides derived from carane, p-menthane, pinane, and bornane were developed. Methyl and dimonoterpenyl sulfides have been obtained by the reaction of the corresponding monoterpene thiolates with methyl iodide or monoterpene tosylates. The reactions of monoterpene tosylates with sodium benzenethiolate gave the corresponding phenyl monoterpenyl sulfides. These sulfides were used for the sulfur ylide-mediated reaction to yield epoxides. Good diastereoselectivities up to 99:1 and low to moderate enantioselectivities were observed for the enantioselective synthesis of chiral epoxides.

Terpenyl Selenides: Synthesis and Application in Asymmetric Epoxidation

“…Lack of enantioselectivity for the trans product was observed (entry 2). Under anhydrous conditions, used for sulfur compounds in our previous work (entries 3 and 4), [11] an increase in the diastereoselectivity and enantioselectivity was observed. The best yield was obtained when BF 4 -counteranion was chosen.…”

“…For selenides 26 and 27 we could not isolate the product (entries 15 and 16). Comparison of the diastereoselectivity and enantioselectivity of the epoxidation reaction of terpenyl sulfides obtained in our previous work [11] with these terpenyl selenides, reveal that sulfides in general led to high diastereoselectivities but low enantioselectivities, whereas terpenyl selenides gave low to moderate diastereoselectivities but, in some cases, very good enantioselectivities. Introduction of the phenyl group instead of the methyl group led to higher enantioselectivities for both sulfides and selenides.…”

“…[11] We therefore decided to prepare the selenium analogues and to compare their reactivity in selenium-mediated asymmetric epoxidation.…”

“…Recently, we presented our results on asymmetric epoxidation through the use of methyl terpenyl, phenyl terpenyl, and diterpenyl sulfides derived from monoterpenes from p- menthane, carane, and pinane group. [11] We therefore decided to prepare the selenium analogues and to compare their reactivity in selenium-mediated asymmetric epoxidation.…”

New and efficient methodology for the synthesis of chiral mono- and ditellurides

“…[6][7][8] They have also gained some additional attention because of their biological capacity; the ability to reduce toxic reactive oxygen species significantly higher than that for analogous selenium derivatives. 9 Previously, we mainly focused on developing effective methods for the synthesis of new optically active monoterpene derivatives containing sulfur 10 and selenium. [11][12][13][14][15][16][17][18][19] The results prompted us to synthesize analogous structures with tellurium.…”