SYNTHESIS, OPTICAL RESOLUTION, AND ABSOLUTE-CONFIGURATION OF PSEUDOTETRAHEDRAL ORGANORHENIUM COMPLEXES (ETA-C5H5)RE(NO)(PPH3)(X)
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abstract
Reaction of [(-C6H5)Re(NO)(PPh3)(CO)]+BF4 (1) with CH3ONa/CH3OH affords the ester (-C5H5)Re(NO)(PPh3)(COOCH3) (2). Reaction of 2 with ()-(S)--(1-naphthyl)ethylamine or (+)-(R)--(1-naphthyl)ethylamine gives amide (-C5H5)Re(NO)(PPh3)(CONHCH(CH3)C10H7) (8). The diastereomers of 8 are separated by benzene/hexane recrystallization; ()-(RS)-8 and (+)-(SR)-8 are least soluble. These are treated with CF3CO2H and NaBF4 to give ()-(R)-1 and (+)-(S)-1, respectively. Resolved 1 is then used to prepare optically active 2, (-C5H5)Re(NO)(PPh3)(CH3) (3), [(,-C5H5)Re(NO)(PPh3)(=CH2)]+PF6 (4), (-C5H5)Re(NO)(PPh3)(CH2C6H5) (9), (-C5H6)Re(NO)(PPh3)(CH2CH3) (10), and (,-C5H5)Re(NO)-(PPh3)(CHO) (11) via known procedures. An X-ray crystal structure of ()-(R)-9 (space group P212121, a = 12.874 (5) , b = 11.889 (3) , c = 16.077 (7) , Z = 4, R = 0.034) establishes the absolute configurations of resolved 14 and 811. Also described are the following: ORD and CD spectra; several unsuccessful resolution attempts; the synthesis of [(-C5H5)Re(NO)(PPh3)(CH2P+Ph2(O-l-menthyl))]+PF6+ (7) (used as an optical purity assay); comparisons with isostructural chiral organometallic complexes. 1982, American Chemical Society. All rights reserved.
