User.ts

import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/catch';
import 'rxjs/add/observable/fromPromise';

class User {
	userPromise() {
		return new Promise((resolve, reject) => {
			if(1 === 1) {
				return resolve([{name: 'Iparra'}])
			}
			return reject({msg: 'error'});
		})
	}

	promiseToObservable() {
		return Observable.fromPromise(this.userPromise())
			.map(user => user[0])
			.catch(error => Observable.throw(err));
	}
}

let user = new User();
user.promiseToObservable().subscribe(
	result => {
		console.log(result); //[{name: 'Iparra'}]
	},
	error => {
		console.log(error);
	}
);