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- Title
Regio- and stereoselective synthesis of tetra- and triarylethenes by N-methylimidodiacetyl boron-directed palladium-catalysed three-component coupling.
- Authors
Lin, E. Emily; Wu, Jia-Qiang; Schäfers, Felix; Su, Xiao-Xuan; Wang, Ke-Feng; Li, Ji-Lin; Chen, Yunyun; Zhao, Xin; Ti, Huihui; Li, Qingjiang; Ou, Tian-Miao; Glorius, Frank; Wang, Honggen
- Abstract
The flexible synthesis of tetra- and triarylethenes bearing different aryl groups has been a long-standing challenge in organic synthesis. Here we report a palladium-catalysed syn-diarylation of arylethynyl N-methyliminodiacetyl (MIDA) boronates. The products, triarylalkenyl N-methyliminodiacetyl boronates, allow a step-economic and modular synthesis of tetra- or triarylethenes via a subsequent stereospecific Suzuki-Miyaura coupling reaction or base-promoted protodeborylation, respectively. Use of the sp3-B(MIDA) masked aryl alkyne is the key factor for success by offering an exceptionally good regioselectivity for the boron-retentive coupling. The unusual regioselectivity is believed to arise from the stabilization due to the strong electron donation from the C−Pd σ bond to the p-orbital of boron in the transition state of migratory insertion. A broad range of differently substituted tetra- and triarylethenes are constructed in good yields and geometrical control. Synthetic manipulation of the C-B bond also enables the facile construction of several other types of tetra-substituted alkenes. The synthesis of tri- and tetra-aryl alkenes is limited by poor regio- and stereoselectivity. Here MIDA boronate-substituted aryl alkynes are used to achieve regioselective three-component diarylation of the alkyne and to provide a cross-coupling handle for subsequent elaboration to tri- or tetra-substituted products.
- Subjects
BORON; ARYL group; ASYMMETRIC synthesis; COUPLING reactions (Chemistry); ALKENES; STEREOSPECIFICITY
- Publication
Communications Chemistry, 2019, Vol 2, Issue 1, pN.PAG
- ISSN
2399-3669
- Publication type
Article
- DOI
10.1038/s42004-019-0137-0