121401-06-7Relevant articles and documents
A catlaytic tellurium process for the transposition of allylic hydroxyl groups and carbon-carbon double bonds
Kumar, Archana,Dittmer, Donald C.
, p. 5583 - 5586 (1994)
As little as 0.1 molar equivalent of elemental tellurium in combination with excess (up to 3 molar equivalents) reducing agent (HOCH2SO2Na·H2O, NaBH4, or LiEt3BH) effects the telluride-ion mediated transposition of allylic hydroxyl groups and carbon-carbon double bonds that proceeds via the epoxy tosylate. The workup is much more convenient than when a molar equivalent of tellurium is used.
De novo synthesis of (+)-isofregenedol
Riou, Maxime,Barriault, Louis
supporting information; experimental part, p. 7436 - 7439 (2009/05/07)
(Chemical Equation Presented) An efficient enantioselective synthesis of (+)-isofregenedol was achieved in 13 steps from commercially available cyclohexene oxide without the use of protecting groups. The tetrahydronaphthalenic core of isofregenedol was ob
A Tellurium Transposition Route to Allylic Alcohols: Overcoming Some Limitations of the Sharpless-Katsuki Asymmetric Epoxidation
Dittmer, Donald C.,Discordia, Robert P.,Zhang, Yanzhi,Murphy, Christopher K.,Kumar, Archana,et al.
, p. 718 - 731 (2007/10/02)
Good yields of enantiomeric allylic alcohols can be obtained in high enantiomeric excess (ee) by combining Sharpless-Katsuki asymmetric epoxidation process (SAE) with tellurium chemistry.The advantages of the tellurium process are as follows: (1) the 50percent yield limitation on the allylic alcohol in the Sharpless kinetic resolution (SKR) can be overcome; (2) allylic tertiary alcohols which are unsatisfactory substrates in the SKR can be obtained in high optical purity; (3) optically active secondary allylic alcohols with tertiary alkyl substituents (e.g. tert-butyl) at C-1 can be obtained in high ee; (4) optically active sterically congested cis secondary alcohols can be obtained in high ee; and (5) the nuisance of the slow SAE of some vinyl carbinols can be avoided.The key step in the reaction sequence is either a stereospecific 1,3-transposition of double bond and alcohol functionalities or an inversion of the alcohol configuration with concomitant deoxygenation of the epoxide function in epoxy alcohols.Trans secondary allylic alcohols can be converted to cis secondary allylic alcohols by way of erythro epoxy alcohols (glycidols); threo glycidyl derivatives are converted to trans secondary allylic alcohols.These transformations are accomplished by the action of telluride ion, generated in situ from the element, on a glycidyl sulfonate ester.Reduction of elemental Te is conveniently done with rongalite (HOCH2SO2Na) in an aqueous medium.This method is satisfactory when Te2- is required to attack at primary carbon site of a glycidyl sulfonate.In cases where Te2- is required to attack a secondary carbon site, reduction of the tellurium must be done with NaBH4 or LiEt3BH.Elemental tellurium is precipitated during the course of the reactions and can be recovered and reused.
