1: 1)Ethyl chloroformate, Triethylamine / 1) from -12 to -15 deg C, 30 min., THF, 2) room temp., overnight, THF 2: 1) sodium hydride / 1) THF, NaH, Cooled 2) room temp., 3 h 3: 98 percent Chromat. / tetrakis(triphenylphosphine)nickel(0), triethylaluminum / tetrahydrofuran; toluene / 4 h / 50 - 60 °C View Scheme

1: 1)Ethyl chloroformate, Triethylamine / 1) from -12 to -15 deg C, 30 min., THF, 2) room temp., overnight, THF 2: 3.2 percent Chromat. / tetrakis(triphenylphosphine)nickel(0), triethylaluminum / tetrahydrofuran; toluene / 5 h / 80 °C View Scheme

in diethyl ether Ring cleavage; Substitution;

diethyl ether

chloroformic acid ethyl ester; triethylamine in tetrahydrofuran T=-12°C; 1 h;