Angular 2 - Ahead-of-time compilation how to

I'm trying to bootstrap my Angular 2 RC5 application following this guide https://angular.io/docs/ts/latest/guide/ngmodule.html Below is my code

import { AppModuleNgFactory } from './app.module.ngfactory';
import {platformBrowser} from "@angular/platform-browser";

platformBrowser().bootstrapModuleFactory(AppModuleNgFactory);

However , when I tried to compile typescript code, I got the following error

appmain.ts(1,36): error TS2307: Caot find module './app.module.ngfactory'.

How can I generate the app.module.ngfactory file? Which tool should I use?