Angular 1.5 & ES6 -Dependency injection

I'm new to angular and i'm trying to use ES6.

I have a problem with dependencies inject, i can't get it to work.

My index.js :

    import './index-state.css!';
    import angular from 'angular';
    import 'angular-ui-router';
    import IndexStateController from './index-state-controller';
    import indexRouteConfig from './index-route';

    const dependencies = [
        'ui.router'
    ];

    export default angular
        .module('index-state-component', dependencies)
        .controller('IndexStateController', IndexStateController)
        .config(indexRouteConfig);

My index-state.controller.js is :

    class IndexStateController {
        constructor($timeout) {
            this.$timeout = $timeout;
            this.controllerName = 'Example Controller';
            console.log(this.$timeout);
        }

    }

    IndexStateController.$inject =['$timeout'];

    export default [
        IndexStateController
    ];

I'm getting 'undefined' on the console.log(this.$timeout).

Can someone help me through this ?

Thanks