sodium tetrahydroborate in ethanol; water 1) 20 deg C, ca. 2 h, 2) 0 deg C, ca. 12 h;

1: cyclopentyl-magnesium chloride With titanium(IV) isopropylate in diethyl ether T=-70 - -30°C; 0.0833333 h; 2: carbon dioxide in diethyl ether T=-70 - -30°C; 0.5 h; 3: With oxygen in diethyl ether T=-70 - -30°C; 1 h; Title compound not separated from byproducts;

/BRN= 3195777/;

1: /BRN= 3196781/ 2: /BRN= 3195777/ View Scheme

in tetrahydrofuran; water T=20 - 25°C; 2 h; Irradiationdifferent reaction time; Product distributionMechanism;