21. The oxetane ring in compound 6.3 was obtained via an Shapiro coupling reaction . 22. Generally the OA-RE mechanism is analogous to palladium-catalyzed cross coupling reactions . 23. The coupling reaction proceeds in two steps: 24. The many reactions catalyzed by palladium compounds are collectively known as palladium-catalyzed coupling reactions . 25. This helps to remove palladium from drugs or precursors synthesized by palladium-catalyzed coupling reactions . 26. Gene disruption studies indicate a cytochrome P450 oxygenase as the enzyme that performs the coupling reactions . 27. The coupling reactions are shown below. 28. Negishi, and Suzuki coupling reactions . 29. They also tend to be thermally unstable, which can be useful in certain coupling reactions . 30. Likewise coupling reactions involving organomanganese halides are catalysed by Pd, Ni, Cu and Fe compounds
