Regio- and stereoselective ring opening of epoxides. Enantioselective synthesis of 2,3,4-trisubstituted five-membered heterocycles

Synthesis of 1,4-imino-L-lyxitols modified at C-5 and their evaluation as inhibitors of GH38 α-mannosidases

“…It should be emphasized that tosylation in the presence of commonly used bases such as pyridine or TEA was sluggish. Subsequent substitution of the tosylate in 8 either with Super-hydride ® (LiBHEt 3 ) or with a cuprate generated in situ from MeMgBr and CuI afforded pyrrolidines 9 [31] and 12 in 68% and 44% yield, respectively (Scheme 1). In the course of tosylate substitution with the cuprate, 3-methylpiperidine 11 was isolated as a byproduct in 32% yield.…”

Cycloadditions and Cyclizations of Acetylenic, Allenic, and Conjugated Dienyl Sulfones

“…As expected from the electron-withdrawing nature of the sulfone group, electrophilic reagents such as peracids − epoxidize the unactivated double bond preferentially, while nucleophilic ones such as alkaline hydrogen peroxide, , t -butyl hydroperoxide, ,− and N -methylmorpholine- N -oxide favor the sulfone-substituted one. Enantioselective and diastereoselective epoxidations have been achieved with Jacobsen’s catalyst ,− ,− or via Sharpless asymmetric epoxidation when an allylic alcohol moiety is also present. , A comparison of the regio- and stereoselectivity of epoxidation of cycloheptatrienyl sulfones with various chiral and achiral reagents, including a dioxirane, was reported by Fuchs et al Furthermore, a very recent review by Fuchs and co-workers describes numerous elegant and highly regio- and stereoselective further transformations of such epoxy sulfones, while earlier work was similarly covered in 1998 by Bäckvall et al Duplication of this material will therefore not be presented here, and the reader is directed to these prior sources for additional information.…”

“…Enantioselective and diastereoselective epoxidations have been achieved with Jacobsen's catalyst 335,[338][339][340][344][345][346][347][348][349][350] or via Sharpless asymmetric epoxidation when an allylic alcohol moiety is also present. 351,352 A comparison of the regio-and stereoselectivity of epoxidation of cycloheptatrienyl sulfones with various chiral and achiral reagents, including a dioxirane, was reported by Fuchs et al 350 Furthermore, a very recent review by Fuchs and co-workers 1 describes numerous elegant and highly regio-and stereoselective further transformations of such epoxy sulfones, while earlier work was similarly covered in 1998 by Ba ¨ckvall et al 22 Duplication of this material will therefore not be presented here, and the reader is directed to these prior sources for additional information.…”

Influence of reaction conditions on the selectivity of the process of epoxidation of oct-1-ene by tert-butyl hydroperoxide in the presence of МоВ

“…Велика кількість епоксидів (більше, ніж 1,5 тис.) природного та синтетичного походження проявляє біологічну активність, тому їх використовують як реагенти для одержання проміжних продуктів та вихідних речовин для синтезу деяких лікарських препаратів − антибіотиків, стероїдів та їх похідних, енантіомерно чистих аналогів природних сполук, протипухлинних препаратів та інших [9][10][11][12][13][14][15][16].…”