acetic acid in tetrahydrofuran; water T=20°C; 24 h;

NaOC(CH3)3; HCl; [CuCl(1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene)] in tetrahydrofuran 1.0 molpercent Cu-complex, alkyne, diborane, NaOC(CH3)3, CH3OH-dioxane, HCl THF, -50°C, 21 h, N2 atm.; detected by NMR spectra 93:7 ratio of isomers;

Multistep reaction;

Dess-Martin periodane in dichloromethane 1.5 h;