Categories: C-O Bond Formation, Synthesis of cyclic ethers >
Synthesis of epoxides
Related |
|
 |
Recent Literature
Key step in the synthesis of chiral phenyloxirane is the enantioselective
catalytic reduction of an achiral chloromethyl ketone by means of a chiral
oxazaborolidine as catalyst and borane as stoichiometric reductant.
E. J. Corey, S. Shibata, R. K. Bakshi, J. Org, Chem., 1988, 53,
2861-2863.
Dynamic kinetic resolution (DKR) of various aromatic chlorohydrins using
Pseudomonas cepacia lipase (PS-C “Amano” II) and a ruthenium catalyst
afforded chlorohydrin acetates in high yields and high enantiomeric excesses.
These optically pure chlorohydrin acetates can be transformed to a wide range of
important chiral compounds.
A. Träff, K. Bogár, M. Warner, J.-E. Bäckvall, Org. Lett.,
2008,
10, 4807-4810.
The Mitsunobu cyclodehydration of chiral phenethane-1,2-diols, readily
accessed from styrene derivatives, provides the corresponding styrene oxides
with high levels of stereoretention for electron-poor substrates. The combination of tricyclohexylphosphine and diisopropylazodicarboxylate in THF
provides the best results.
S. A. Weissman, K. Rossen, P. J. Reider,
Org. Lett., 2001, 3, 2513-2513.
Acetylenic epoxides are directly prepared by nucleophilic ring closure of
propargylic alkoxides generated by lithium acetylide addition to α-haloketones.
A subsequent, mild and efficient cycloisomerization in the presence of InCl3
as catalyst delivers 2,3,5-trisubstituted furans.
J. Y. Kang, B. T. Connell, J. Org. Chem., 2011,
76, 2379-2383.
Alkynyl halides serve as a source of Br+ and acetylide ions in an
efficient one-step preparation of alkynyl epoxides, important organic building
blocks, from readily available starting materials.
A. Trofimov, N. Chernyak, V. Gevorgyan, J. Am. Chem. Soc., 2008,
130, 13538-13539.
The regioselective synthesis of several aminoepoxides has been achieved without
observing any trace of azetidinols. The use of the mild supported base KF-Celite
in refluxing acetonitrile is crucial for modulating the excellent
regioselectivity observed.
V. Pace, P. Hoyos, J. V. Sinisterra, A. R. Alcántara, W. Holzer, Synlett, 2011,
1831-1834.
The aza-Payne rearrangement of 2,3-aziridin-1-ols under basic conditions gives
epoxy amines. Subsequent nucleophilic attack of the epoxide by
dimethylsulfoxonium methylide yields a bis-anion, which upon a 5-exo-tet
ring-closure yields the desired pyrrolidine. This process takes place with
complete transfer of stereochemical fidelity and can be applied to sterically
hindered aziridinols.
J. M. Schomaker, S. Bhattacharjee, J. Yan, B. Borhan, J. Am. Chem. Soc., 2007,
129, 1996-2003.
