Use of tellurium(IV) and tellurium(VI) as oxidants in organic synthesis

Abstract

mg, 0.48 mmol) at 60 °C for 4 h followed by evaporation in vacuo to dryness. The residue was dissolved in ether and washed with 5% NaHC03, dried (MgS04), and evaporated to dryness. The crude material was purified by preparative TLC to yield the pure compound: 158 mg (88%); mp 114-116 °C (recrystallized from methanol); IR 1664 cm"1 11(C(O)NH); NMR 0.66 (3 H, s, 18-Me), 0.97 (3 H, s, 19-Me), 3.73 (1 H, br s, 3a-H), 4.5 (2 H, s, benzylic protons), 5.27 (1 H, br s, 15-H), 6.

NaIO4/LiBr-mediated Diastereoselective Dihydroxylation of Olefins: A Catalytic Approach to the Prevost−Woodward Reaction

“…Surprisingly, when (1,2-dibromoethyl)benzene was subjected to this solvolysis, bromides at benzylic as well as homobenzylic positions underwent solvolysis to give regioisomers of diol derivative 2a and 2b in excellent yield. Although oxidation of benzylic bromides by TeO 2 has been reported, the present protocol constitutes the first report on the oxidation of non-benzylic halides, anchimerically assisted by acetyl groups present at the 2-positions.…”

A tribute to Professor Jan Bergman

“…The dimeric indole alkaloid yuehchukene (14) was isolated from various Murruya species and was reported to display strong anti-implantation activity in rats. The Bergman total synthesis (Scheme 3) required just five steps and proceeded with total regio-and stereochemical selectivity 23 .…”

Tellurium tetrachloride: Addition to cyclohexene and preparation from tellurium dioxide and trimethylchlorosilane

“…The tellurium compound is formed by mixing tellurium dioxide, lithium chloride, and acetic acid. Subsequently, the usefulness of tellurium(1V) compounds as oxidizing agents for organic molecules was explored [4-81. In these reactions, car- ried out in acetic acid in the presence of lithium chloride [5] or lithium bromide [4,6] and catalytic amounts of tellurium dioxide, alkenes were oxidized with molecular oxygen to vic-diacetates , and conjugated dienes to 1,4-diacetoxyalk-2-enes [8]. The reported speculations about the mechanism of these reactions [4-81 generally lack experimental support.…”