Lithiation and Reactions of Stilbene Oxides: Synthetic Utility
摘要:
The lithiation of trans- and cis-stilbene oxides (+/-)-1 and 8 has been investigated. While with 8, lithiation occurred exclusively at the benzylic position, with the trans isomer (+/-)-1, ortho-lithiation competed with alpha-lithiation depending upon the experimental conditions. The configurational stability of the alpha-lithiated cis- and trans-stilbene oxides (+/-)-2 and (+/-)-9, respectively, was proved as well as that of scalemic stilbene oxide (R,R)-2.
The cyclization reaction of diallyldibutyltin and α- or γ-halo ketones, especially chloro-substituted ketones, effectively proceeds in the presence of a catalytic amount of tetraethylammonium chloride, producing the corresponding 2-allyloxiranes or 2-allyltetrahydrofurans in high yield, respectively. β-Chloro ketones give the corresponding allyl alcohols.
The lithiation of trans- and cis-stilbene oxides (+/-)-1 and 8 has been investigated. While with 8, lithiation occurred exclusively at the benzylic position, with the trans isomer (+/-)-1, ortho-lithiation competed with alpha-lithiation depending upon the experimental conditions. The configurational stability of the alpha-lithiated cis- and trans-stilbene oxides (+/-)-2 and (+/-)-9, respectively, was proved as well as that of scalemic stilbene oxide (R,R)-2.