1: With borane-THF; chiral 2-methyl-1-oxa-3-aza-2-boracyclopenta[a]indene in tetrahydrofuran T=25°C; 18 h; 2: With sodium tetrahydroborate in ethanol T=50°C; 4 h; 3: With sulfuric acid T=80°C; 2 h;