65173-63-9Relevant academic research and scientific papers
Optimisation of enantioselectivity for the chiral base-mediated rearrangement of bis-protected meso-4,5-dihydroxycyclohexene oxides: Asymmetric synthesis of 4-deoxyconduritols and conduritol F
De Sousa, Simon E,O'Brien, Peter,Pilgram, Christopher D
, p. 4643 - 4654 (2007/10/03)
A strategy based on diastereoselective epoxidation of a cyclohexene followed by chiral lithium amide-mediated epoxide rearrangement has been used to synthesise an allylic alcohol building block of >95% ee. The key step is the enantioselective rearrangement of a bis-protected meso-4,5-dihydroxycyclohexene oxide. A range of protecting groups and chiral base structures were surveyed in order to find the optimum protocol for high enantioselectivity. Using a tert-butyldimethylsilyloxy protecting group and a norephedrine-derived chiral base, a 93% yield of an allylic alcohol of >95% ee was achieved. To demonstrate the synthetic utility, this allylic alcohol was subsequently transformed into 4-deoxyconduritols and (+)-conduritol F.
Chiral lithium amide base-mediated rearrangement of bis-protected meso-4,5-dihydroxy cyclohexene oxides: Enantioselective synthesis of (4R,5S) and (4S,5R)-4,5-bis(tert-butyldimethylsilyloxy)cyclohex-2-enone
O'Brien, Peter,Poumellec, Pierre
, p. 2435 - 2441 (2007/10/03)
The asymmetric synthesis of (4R,5S)- and (4S,5R)-4,5-bis(tert-butyldimethylsilyloxy)cyclohex-2-enone are described. Such bis-protected enones are useful intermediates in synthesis, and compounds with (4S,5R)-stereochemistry have previously been prepared from D-(-)-quinic acid. This paper reports the first synthesis of enones with (4R,5S)-stereochemistry. The route to the bis-protected enones involves chiral base-mediated rearrangement of meso-cyclohexene oxides to allylic alcohols followed by PDC oxidation. Two new chiral base reactions are described: rearrangement of a trans-epoxide generates an allylic alcohol of 76% ee (93% yield) whilst that of a cis-epoxide produces an allylic alcohol of 92% ee (38% yield); suggestions for the observed differences in yield and enantioselectivities are proposed.
Chiral base-mediated rearrangement of meso-cyclohexene oxides to allylic alcohols
O'Brien, Peter,Poumellec, Pierre
, p. 8057 - 8058 (2007/10/03)
Highly enantiomerically enriched allylic alcohols have been generated by rearranging single diastereomers of meso-cyclohexene oxides using a homochiral lithium amide base. PDC oxidation of each allylic alcohol product affords a different enantiomer of a synthetically useful cyclohexenone.
Preparation of Optically Active γ-Hydroxyethyl α,β-Unsaturated γ-Lactone Using an Enzymatic Procedure
Suemune, Hiroshi,Hizuka, Michiyo,Kamashita, Tomoko,Sakai, Kiyoshi
, p. 1379 - 1381 (2007/10/02)
γ-Hydroxyethyl α,β-unsaturated γ-lactone (2) is a promising intermediate for the synthesis of eldanolide and cis,cis-1,2,3-trisubstituted cyclopentane, which could be converted to 11-deoxyprostaglandins.In order to prepare optically active 2, enzymatic hy
