197219-12-8Relevant articles and documents
Asymmetric iodocyclization catalyzed by salen-CrIIICl: Its synthetic application to swainsonine
Kwon, Hyo Young,Park, Chul Min,Lee, Sung Bae,Youn, Joo-Hack,Kang, Sung Ho
, p. 1023 - 1028 (2008/09/21)
The previously developed enantioselective iodocyclization of γ-hydroxy-cis-alkenes required 30 mol% of (R,R)-salen-CoII complex as chiral catalyst and 0.75 equivalent of N-chlorosuccinimide (NCS) as activator to produce 2-substituted tetrahydrofurans with 61 to 90% ee. Due to the considerable loading amount of the CoII complex, another more effective catalyst was pursued by screening (R,R)-salentransition metal complexes. When 10 mol % of the catalysts were applied with 0.5 equivalent of NCS, a higher level of stereoselectivity was attained with the corresponding CrIIICl (84% ee), MnIICl (52% ee) and CoII complexes (66% ee). Refinement of the conditions established a novel catalytic enantioselective iodocyclization protocol using iodine in the presence of 7 mol% of (R,R)-salen-CrIIICl complex activated by 0.7 equivalent of NCS in toluene to induce 74 to 93 % ee.
The biomimetic construction of fused cyclic polyethers
Hayashi, Nobuyuki,Fujiwara, Kenshu,Murai, Akio
, p. 12425 - 12468 (2007/10/03)
The formation of fused cyclic ethers by biomimetic synthesis was demonstrated. The one-pot successive ring-expansion reactions of bromo diepoxides were investigated by regarding the epoxy groups as the nucleophiles for the intramolecular cationic carbons to obtain the fused cyclic ethers.
