NωAlkylnitrosocarbamoyl-α,ω-diaminocarboxylic acids. 2. Synthesis and antitumor activity of nitroso derivatives of Nω-(2-chloroethyl)-carbamoyl-α,ω-diaminocarboxylic acids-(2-chloroethyl)-carbamoyl-α,ω-diaminocarboxylic acids