1: 1.) thionyl chloride / THF; 1.) reflux, 4 h; 2.) room temp., 12 h 2: 94 percent / hydrogen / Pd/C / ethanol / 8 h 3: acetonitrile; H2O / 50 °C / rate constants (kOH) for lactonization (buffered solution pH 10.0); other temp.: 70, 90 deg C 4: 91 percent / lithium aluminum hydride / tetrahydrofuran View Scheme