TRANSITION METAL COMPLEX, PREPARATION METHOD FOR SAID TRANSITION METAL COMPLEX, TRIMERIZATION CATALYST, PREPARATION METHOD FOR 1-HEXENE, PREPARATION METHOD FOR ETHYLENE POLYMER, SUBSTITUTED CYCLOPENTADIENE COMPOUND, AND PREPARATION METHOD FOR SAID SUBSTITUTED CYCLOPENTADIENE COMPOUND
申请人:Sumitomo Chemical Co., Ltd
公开号:EP2484685B1
公开(公告)日:2017-11-01
Desymmetrization of Cyclohexadienylsilanes. Regio-, Diastereo-, and Enantioselective Access to Sugar Mimics
Desymmetrization of cyclohexadienylsilanes available from Birch reduction of the corresponding arylsilanes is efficiently carried out using Sharpless asymmetric dihydroxylation and aminohydroxylation. Complete diastereocontrol and reasonable enantiocontrol have been attained during the preparation of the desired diols. An excellent regiocontrol has also been observed during aminohydroxylation of dienylsilanol 6b. The resulting diol 8 and hydroxycarbamate 27 have then been elaborated further, offering a straightforward access to various types of cyclitols, aminocyclitols, carbasugars, as well as the antibiotic palitantine 4. The complete functionalization of the original arylsilanes 5 is thus typically achieved in fewer than eight steps with high stereoselectivities and excellent overall yield.
RUHLMANN K.; SCHILLING P., Z. CHEM., 26,(1986) N 12, 447-448