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Enantioselective 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds catalyzed by rhodium(I)-chiral phosphoramidite complexes
| Content Provider | Semantic Scholar |
|---|---|
| Author | Sugishita, Noriyuki Oshita, Kengo Piao, Dongguo Yamamoto, Yasunori Miyaura, Norio |
| Copyright Year | 2017 |
| Abstract | A 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, R, R=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 (R, R=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. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/18877/1/JOC692_1-3.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |