1: (5R)-6,7-dihydro-3,9,10,11-tetramethoxy-5H-dibenzo[a,c]cyclohepten-5-ol With Zn(N3)2/bis-pyridine complex; di-isopropyl azodicarboxylate; triphenylphosphine in toluene 4 h; Inert atmosphere; 2: With hydrogen in ethanol 20 h; Inert atmosphere; 3: acetic anhydride With pyridine in dichloromethane T=0 - 20°C; 12 h; Inert atmosphere; optical yield given as percent ee;

Multi-step reaction with 4 steps 1.1: triethylsilane; bis(trimethylsilyl)-acetylene / 1,2-dichloro-ethane / 6 h / 65 °C / Inert atmosphere1.2: 12 h / 20 °C / Inert atmosphere2.1: borane-THF / tetrahydrofuran / 0 - 20 °C / Inert atmosphere2.2: 4.5 h / 20 - 40 °C / Inert atmosphere3.1: oxalyl dichloride; dimethyl sulfoxide; N-ethyl-N,N-diisopropylamine / dichloromethane / 6 h / -78 - 20 °C / Inert atmosphere4.1: lithium borohydride; (L)-TarB-NO2 / tetrahydrofuran / 0.58 h / Inert atmosphere