Enviar texto al Bloc de Notas

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Diagnostics;

namespace Navegar
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
String textoentrada = textBox1.Text;
Clipboard.SetText(textoentrada);
Process.Start("notepad.exe");
}

private void button2_Click(object sender, EventArgs e)
{
Application.Exit();
}

private void button3_Click(object sender, EventArgs e)
{
textBox1.Clear();
}
}
}