1: benzoyl chloride With sodium azide; N-benzyl-N,N,N-triethylammonium chloride in toluene T=60 - 80°C; Curtius rearrangement; 1.25 h; 2: 1-hydroxycyclopentane in toluene T=20°C;

1: benzoyl hydroxylamine With DMEG; triethylamine in dichloromethane T=20°C; Rearrangement; 0.5 h; 2: 1-hydroxycyclopentane in dichloromethane T=20°C; Addition; 48 h;

boron trifluoride diethyl etherate in benzene 0.25 h; Ambient temperature;

1: bis-[(trifluoroacetoxy)iodo]benzene / 1,2-dichloro-ethane / 0.03 h / |Molecular sieve; |Inert atmosphere 2: 1,2-dichloro-ethane / 1 h / 60 °C / |Molecular sieve; |Inert atmosphere View Scheme