1: With 3-chloro-benzenecarboperoxoic acid in dichloromethane T=-78°C; 1 h; 2: With calcium carbonate in xylene T=160°C; 18 h; Further stages.;

tetra-n-butylammonium difluorotriphenylsilicate(IV) in acetonitrile T=85°C; 1 h;

acetic acid; zinc in acetic acid T=50°C; Reduction; 18 h; washing with CHCl3; evapg.; isolation by PTLC;

1.1: lithium diisopropylamide / tetrahydrofuran; hexane / 0.58 h / -78 °C 1.2: 83 percent / tetrahydrofuran; hexane / 0.42 h / -78 °C 2.1: 96 percent / dichlorobis(triphenylphosphine)palladium(II) / dimethylformamide / 20 h / 100 °C 3.1: BF3*OEt2; 9-borabicyclo[3.3.1]nonane / tetrahydrofuran / 15 h / 0 °C 3.2: 43 percent / N,N,N',N'-tetramethylethylenediamine; H2O2; NaOH / tetrahydrofuran; H2O / 0 °C 4.1: 82 percent / o-iodoxybenzoic acid / dimethylsulfoxide / 1 h / 20 °C 5.1: 54 percent / tetrabutylammonium triphenylsilyldifluoride / acetonitrile / 1 h / 85 °C View Scheme

1: 86 percent / POCl3 / 4 h / 120 - 125 °C / extn. with satd. NaHCO3; drying over Na2SO4; purification by PTLC 2: 35 percent / Zn; acetic acid / acetic acid / 18 h / 50 °C / washing with CHCl3; evapg.; isolation by PTLC View Scheme