1: 3-oxo-2,8-diazaspirolt;4.5gt;decane-8-carboxylic acid tert-butyl ester With sodium hydride in tetrahydrofuran T=5°C; 1 h; 2: furan-3-carboxylic acid chloride in tetrahydrofuran T=0 - 20°C; 3 h;