2024-03-28T15:33:06Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/188772022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139Enantioselective 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds catalyzed by rhodium(I)-chiral phosphoramidite complexesKurihara, KazunoriSugishita, NoriyukiOshita, KengoPiao, Dongguo1000030271646Yamamoto, YasunoriMiyaura, Norioopen accessArylboronic acidsRhodium catalystPhosphoramiditeAsymmetricConjugate addition437.8A chiral bidentate phosphoramidite (5a) was synthesized from Shibasaki’s linked-(R)-BINOL and P(NMe2)3 as a new ligand for rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds. The effects of 5a and Feringa’s monodentate phosphoramidite (4, R1, R2 = Et) on the yields and enantioselectivities were fully investigated. The reaction was significantly accelerated in the presence of a base such as KOH and Et3N, allowing the reaction to be completed at the lower temperatures than 50 °C. The addition to cyclic enones such as 2-cyclopentenone, 2-cyclohexenone and 2-cycloheptenone at 50 °C in the presence of an [Rh(coe)2Cl]2-4 (R1, R2 = Et) complex resulted in enantioselectivities up to 98%, though it was less effective for acyclic enones (0–70% ee). On the other hand, a complex between [Rh(nbd)2]BF4 and 5a completed the addition to cyclic enones within 2 h at room temperature in the presence of Et3N with 86–99% yields and 96–99.8% ee. This catalyst was also effective for acyclic enones, resulting in 62–98% yields and 66–94% ee. The 1,4-additions of arylboronic acids to unsaturated lactones and acyclic esters with rhodium(I)-phosphoramidites complexes were also investigated.Elsevier2007-01-01engjournal articleAMhttp://hdl.handle.net/2115/18877http://www.sciencedirect.com/science/journal/0022328Xhttps://doi.org/10.1016/j.jorganchem.2006.04.0420022-328X0022-328XJournal of Organometallic Chemistry6921-3428435https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/18877/1/JOC692_1-3.pdfapplication/pdf171.27 KB2007-01-01