React with MVC data annotations and unobtrusive validation
it should not be possible.
These are two differents ways to delvelop the ui.The razor way is preprocessing the markup code in server side to fill it.
And react works in another flow using the lifecycle methods, you should have already loaded the data-anotations values for accessing it on render.
Therefore, to make this works you have to run razor engine first to fill the markup and next using react engine. I don't recommend use this approach because it's too hard to develop on it and the developers team have to keep that flow in mind while they are developing
Note this
ReactDOM.render(<ComponentMustHaveJSX/>)