Palladium(II)-Catalyzed Ortho-Arylation of Benzylic Phosphonic Monoesters Using Potassium Aryltrifluoroborates

Abstract

The new monophosphonic acid directing group was successfully utilized in the Pd (II)-catalyzed ortho-arylation of benzylic phosphonic monoesters using potassium aryltrifluoroborates. A wide range of benzylic phosphonic monoesters underwent clean ortho-arylation in high yields, and excellent functional group tolerance was also observed.

Synthesis of tertiary alkylphosphonate oligonucleotides through light-driven radical-polar crossover reactions

“…Other standard methods utilizing a Lewis acid catalyst and an alcohol as the source of the alkyl group were also investigated. These trials employed trimethylsilyl trifluoromethanesulfonate or zinc iodide (ZnI 2 ) together with 2-phenyl-2-propanol ( 5a ) and 1a-1 while also heating the reaction solution 38 , 39 . Unfortunately, none of the intended product (the alkyl phosphonate 3aa ) was produced but rather a complex mixture of various compounds was generated.…”

C–H Bond Activation for Arylations

“…Meng and Kim [14] reported the Pd(II)-catalyzed ortho-arylation of benzylic phosphonic monoesters using potassium aryltrifluoroborates in 2013 (Figure 4.6). This transformation is quite important owing to the wide applications of organophosphonates in organic chemistry.…”

Phosphinic Amide as Directing Group Enabling Palladium(II)‐Catalyzed ortho C−H Alkenylation of Anilines without and with Alkylation at the Nitrogen Atom

“…[2e] An interesting case is the CÀHa lkenylation of anilides directed by as ulfonyl-tethered pyridyl group where it is 4b with an NMe group that participates in the catalysis while 4a with an NH group is totally unreactive (Scheme 1, bottom). [2h] Recently,adiverse range of phosphorus-based donors groups was applied to directed transition-metal-catalyzed CÀH bond functionalization (Figure 1), [4][5][6] andt hese performed efficiently in, for example, palladium(II)-catalyzed CÀHa lkenylati on [4a, c, d] and arylation [4b, f] of arenes. Amide derivatives had been included into these reports but not to enable CÀHb ond activation at the amide nitrogen substituent.…”

“…Acetic acid was superior to other solvents that gave either lower or no conversion (see the Supporting Information for as olvent screen). Other mild oxidants such as Cu(OAc) 2 ,A gOAc,a nd Ag 2 CO 3 were not effective (entries [2][3][4]. In turn, the use of peroxydisulfates Na 2 S 2 O 8 and K 2 S 2 O 8 greatly improved conversion and isolated yield (entries 5a nd 6).…”