In react-admin get access to redux store

When you say that you need to dispatch an action outside the scope of a component, I suppose that it's in reaction to another action that was dispatched in the past.

In that case, that's what react-admin calls a side effect. React-admin handles side effects using redux-saga. Here is how to create a custom saga:

// in src/bitcoinSaga.js
import { put, takeEvery } from 'redux-saga/effects';
import { showNotification } from 'react-admin';

export default function* bitcoinSaga() {
    yield takeEvery('BITCOIN_RATE_RECEIVED', function* () {
        yield put(showNotification('Bitcoin rate updated'));
    })
}

Register this saga in the <Admin> component as follows:

// in src/App.js
import React from 'react';
import { Admin } from 'react-admin';

import bitcoinSaga from './bitcoinSaga';

const App = () => (
    <Admin customSagas={[ bitcoinSaga ]} dataProvider={simpleRestProvider('http://path.to.my.api')}>
        ...
    </Admin>
);

export default App;

This is documented in the react-admin documentation, in the <Admin> chapter.