2-Hydroxyisobutyric acid → 2-hydroxy-2-methyl-propionic acid(S)-2-[(1R,3aR,4S,7aR)-4-(tert-butyl-dimethyl-silanyloxy)-7a-methyl-octahydro-inden-1-yl]-propyl ester

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

200 mg (0,612 mmol) of (S)-2-[(1R,3aR,4S,7aR)-4-(tert-butyl-dimethyl-silanyloxy)-7a-methyl-octahydro-inden-1-yl]-propan-1-ol was dissolved in THF (2 ml). PPh3 (169 mg; 0,643 mmol) was added and the mixture cooled to 0° C. To this, a solution of DEAD (95 mg; 0,612 mmol) and 2-hydroxy-isobutyric acid (64 mg; 0,612 mmol) in THF (2 ml) was added dropwise via cannula. After four hours the reaction mixture was poured in cold water, extracted with ether and dried over Na2SO4. Removal of the solvent and silica gel column chromatography (eluent hexane/ethyl-acetate 85/15) of the residue afforded 232 mg (91%) of 2-hydroxy-2-methyl-propionic acid(S)-2-[(1R,3aR,4S,7aR)-4-(tert-butyl-dimethyl-silanyloxy)-7a-methyl-octahydro-inden-1-yl]-propyl ester (K1) as a yellow oil.

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