Fluorine-containing optically active allylic alcohols: preparation and Claisen rearrangement as a new entry to highly functionalized fluorinated amino alcohol derivatives
Abstract
The reaction of Garner aldehyde 1 with 2-bromo-3,3,3-trifluoropropene in the presence of Zn–Ag couple gave the fluorine-containing, optically active allylic alcohol 2 in 65% yield with a diastereomeric excess greater than 98%. The treatment of Garner aldehyde 1 with CF3CFBr2 (3a) and CF3CCl3 (3b) in the presence of zinc powder and catalytic AlCl3 highly diastereoselectively afforded 4a and 4b, respectively, in moderate yield. The orthoester Claisen rearrangement of 4a, b and 2 provided a new way to highly functionalized amino alcohol derivatives 6a–f containing a limited number of fluorine atoms.