It has been established that the oxidative sp(2) C-H bond allylation with aliphatic alkenes proceeds under mild conditions by using heteroarenes as directing groups and an (electron-deficient η(5)-cyclopentadienyl)rhodium(III) complex, [Cp(E)RhCl2]2, as a precatalyst. In sharp contrast, the use of [Cp*RhCl2]2 instead of [Cp(E)RhCl2]2 led to a complex mixture of products under the same reaction conditions.

The oxidative olefination of sp(2) C-H bonds of anilides with both activated and unactivated alkenes using an (electron-deficient η(5) -cyclopentadienyl)rhodium(III) complex is reported. In contrast to reactions using this electron-deficient rhodium(III) catalyst, [Cp*RhCl2 ]2 showed no activity against olefination with unactivated alkenes. In addition, the deuterium kinetic isotope effect (DKIE) study revealed that the C-H bond cleavage step is thought to be the turnover-limiting step.

Here we describe the research and development of a process for the practical synthesis of glucokinase activator (R)-1 as a potential drug for treating type-2 diabetes. The key intermediate, chiral α-arylpropionic acid (R)-2, was synthesized in high diastereomeric excess through the diasteromeric resolution of 7 without the need for a chiral resolving agent. The counterpart 2-aminopyrazine derivative 3 was synthesized using a palladium-catalyzed C−N coupling reaction. This efficient process was demonstrated at the pilot scale and yielded 19.0 kg of (R)-1. Moreover, an epimerization process to obtain (R)-7 from the undesired (S)-7 was developed.

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The concise synthesis of a fungal metabolite, (+)-fusarochromanone (FC-101), was achieved via the oxidative sp 2 CH bond olefination of an N-acetylaminochromanone with a chiral functionalized electron-rich alkene, catalyzed by an electron-deficient (η 5 -cyclopentadienyl)rhodium(III) complex, [Cp E RhCl 2 ] 2 , under ambient conditions as the key step. This protocol was applied to various acetanilides and functionalized electron-rich alkenes for the syntheses of fusarochromanone analogs.