1: 9-tert-butyloxycarbonylamino-4,5-diazafluorene-9-carboxylic acid hydrazide With hydrogenchloride; isopentyl nitrite in ethyl acetate; N,N-dimethyl-formamide T=-40°C; 0.5 h; 2: L-alanine methyl ester hydrochloride With N-ethyl-N,N-diisopropylamine in N,N-dimethyl-formamide T=-40 - 20°C; Further stages.;