1: 3,4-dihydro-2H-pyran With n-butyllithium; potassium tert-butylate in tetrahydrofuran T=-78°C; 1 h; Cooling with acetone-dry ice; 2: boric acid trimethyl ester in tetrahydrofuran T=0°C; 1 h; Cooling with ice; 3: 2,3-dimethylbutane-2,3-diol in tetrahydrofuran; acetic acid T=20°C;

4,4'-di-tert-butyl-2,2'-dipyridyl; bis(η4-1,5-cyclooctadiene)-di-μ-methoxy-diiridium(I) in octane T=80°C; 8 h; Title compound not separated from byproducts.;

catalyst:(Ir(COD)OCH3)2/2(4,4'-di-tert-butyl-bipy) in hexane heating in hexane at 25-80°C in the presence of (Ir(OMe)(COD))2/2(4,4'-di-tert-butyl-bipy); (.alpha/β=95/5);