The rapid development of enantioselective C-H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar-chiral rhodium catalyst [(C H Bu CH Bu)RhI ] in two steps from commercially available [(cod)RhCl] and tert-butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)-proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee).

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Catalytic reaction of arylhydroxamic acids with alkenes represents a convenient method for preparation of biologically active dihydroisoquinolones. Here, the rhodium(III) complex [(C H tBu CH tBu)RhCl ] , which allows one to carry out such reactions with high regioselectivity to obtain 4-substituted dihydroisoquinolones in 72-97 % yields, is described. The regioselectivity is provided by the bulky cyclopentadienyl ligand of the catalyst, which is formed through a [2+2+1] cyclotrimerization of tert-butylacetylene. The catalytic reaction tolerates various distant functional groups in alkenes, but is inhibited by bulky (e.g., tBu) or strongly coordinating (e.g., imidazolyl) substituents. Some of the prepared dihydroisoquinolones effectively inhibit growth of phytopathogenic fungi.

The rapid development of enantioselective C−H activation reactions has created a demand for new types of catalysts. Herein, we report the synthesis of a novel planar‐chiral rhodium catalyst [(C5H2tBu2CH2tBu)RhI2]2 in two steps from commercially available [(cod)RhCl]2 and tert‐butylacetylene. Pure enantiomers of the catalyst were obtained through separation of its diastereomeric adducts with natural (S)‐proline. The catalyst promoted enantioselective reactions of aryl hydroxamic acids with strained alkenes to give dihydroisoquinolones in high yields (up to 97 %) and with good stereoselectivity (up to 95 % ee).

We report the synthesis and crystallographic characterization of a novel Au(III)À OH complex featuring a N^N^N-pincer ligand. Reactivity studies towards oxygen atom transfer (OAT), a type of reactivity previously reported for a Au(III)À OH complex, indicate that this complex provides both a sterically encumbered Au atom and a sterically poorly accessible OH group leading to no reactivity with a series of phosphines. The steric encumbrance sets this example apart from the known examples of Au(III)À OH (pincer) complexes, which commonly feature planar ligands that provide little control over steric accessibility of the Au and O atoms in these complexes. Implications for the mechanism of OAT from AuÀ OH complexes are briefly discussed.Only few examples of structurally defined Au(III) hydroxide complexes have been reported featuring pincer-type ligands, [1] and for most, little is known regarding their reactivity (Figure 1). [2] A notable feature of all reported complexes thus far is that the ligands are planar and therefore provide comparable steric environments. AuÀ OH complexes in general, both Au(I) and Au(III), can be used as synthons to introduce for example anionic ligands, such as a hydride, aryls, and N-heterocycles by ligand exchange. [2c,3] Among the Au(III)À OH complexes an exceptionally wellstudied example is the (C^N^C)AuÀ OH complex from the Bochmann group, which not only serves as a synthon, but also undergoes oxygen atom transfer (OAT) with various phosphines to form the corresponding phosphine oxides and Au(III)À H (Figure 2). [4] Based on a series of experiments, the Bochmann group proposed a concerted mechanism for OAT in which there is planar attack of the phosphine directly onto the oxygen leading to both P=O bond formation and proton reduction giving a AuÀ H (Figure 2). The possibility of an initial AuÀ P interaction was judged unlikely based on DFT calculations [4] and further corroborated by a computational study on the corre-[a