Aerobic Oxidative Cross-Coupling of Substituted Acrylamides with Alkenes Catalyzed by an Electron-Deficient CpRh^III Complex

Abstract

It has been established that an electrondeficient CpRh III complex, bearing two ester moieties on the Cp ring, [Cp E Rh III ], catalyzes the aerobic oxidative cross coupling of substituted acrylamides with both activated and unactivated alkenes, leading to (2Z,4E)-dienamides, at relatively low temperature (80 °C). Importantly, tertiary, secondary, and primary amide directing groups could equally be used in this catalysis. The mechanistic studies revealed that the electron-deficient nature of the Cp E Rh III complex facilitates the turnover-limiting vinylic C−H bond cleavage of the acrylamides.

Synthesis of Novel Pseudocloso Ruthenacarboranes based on an Unsubstituted nido‐C2B9H112− Ligand

“…The reaction of the known 3-H-3-Cl-3,3-(PPh 3 ) 2 -closo-3,1,2-RuC 2 B 9 H 11 (1) with the corresponding tridentate nitrogen-based ligands obtained from picolylamine in benzene at 60 °C resulted in the formation of the novel ruthenacarboranes 2-6 with moderate yields (Scheme 1). The possible mechanism of the process involves the exchange of two PPh 3 ligands by two arms of nitrogen-based ligand typical for 1, following by the elimination of HCl and coordination of the third arm of the ligand.…”

“…for RuC 14 B 9 H 24 N 3 : C, 38.9; H, 5.6; N, 9.7). IR: v max = 2507 cm À 1 , NMR ((CD 3 ) 2 SO, 400 MHz), 1…”

“…Closo-ruthenacarborane clusters of transition metals are often considered as isolobal analogues of cyclopentadienyl (Cp) derivatives and may replace them for example in catalytical applications. [1][2][3] Contrary to Cp dicarbollide dianion bears double negative charge which makes it possible to stabilize higher oxidation states of transition metals which may be useful in some cases. Another peculiarity of the dicarbollide ligand is the observed possibility of elongation of the bond between carbon atoms of carborane cage (C c À C c ) leading to the formation of hypercloso (or isocloso), [4][5][6] arachno [7] or pseudocloso [8][9][10][11][12][13][14] complexes.…”

Recent advances in rhodium-catalysed cross-dehydrogenative-coupling between two C(sp2)–H bonds

“…In 2019, Tanaka, Shibata and co-workers disclosed the aerobic cross-coupling between two vinyl alkenes using an electron-deficient CpRh( iii ) complex in which the cyclopentadienyl ring bears ester moieties (Scheme 3). 15 This strategy enabled the synthesis of (2 Z ,4 E )-configured dynamite derivatives. The catalytic turnover-limiting step ( i.e.…”

How the electron-deficient Cp ligand facilitates Rh-catalyzed annulations with alkynes

“…3 Besides, the change of the electronic properties of Cp ligands, particularly the electron-deficient Cp ligands, leads to a high-level catalytic efficiency. 4,5,6 For instance, Tanaka and co-workers developed a bis(ethoxylcarbonyl)-substituted cyclopentadienyl Rh catalyst (Cp E Rh( iii ), 4 b,c which affords higher yields of annulation products than the Rh catalyst with an electron-rich Cp* ligand (Scheme 1). Rovis and others reported that the Rh catalyst supported by Cp* CF3 shows higher reactivity and regioselectivity in a few types of annulation and coupling reactions.…”