in tetrahydrofuran; anhydrous butyl ether The ester and Cr(CO)6 were treated with dibutyl ether and then THF, and the soln. was refluxed (N2). The react. was monitored by thin layer chromy. (C6H12/ether, 9/1).; Filtration, evapn. of solvent; Flash chromy. and development with hexane resolved 2 bands; 1. band, C6H6Cr(CO)3, 2. band mixt. of diastereomers (90percent, α/β=7/3); isopiestic crystn. at 4°C gave the α-isomer; elem.anal.;