amino acids

I can't seem to think of how nitrous acid is involved but...do check these out -:
http://www.tutornext.com/preparation-methods-amino-acids/2925

hey,rish as u know that the given ester has active methylene group,so it reacts wid HNO2+NaNO2+HCl wherE AN SN REACTION UNDERGOES +LiAlH4 OR NaBH4 AND THE SUBSEQUENT HYDROLYSIS WOULD PRODUCE A ZWTTER ION LIKE STRUCTURE OF GLYCINE.