ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Stereoselective Syntheses of Substituted Tricarbonyl[tris(methylen)methan]iron(0) ComplexesThe complexes 3, 9, 10, 22, and 23 with one, two, and three Me substituents at the tris(methylen)methane moiety have been synthesized from the (acyloxy-1,3-diene)(tricarbonyl)iron(0) complexes 1, 4, 5, 20, and 21, respectively, by ionic hydrogenation with BF3 and Et3SiH at -78° in CH2C12. These reductions are completely stereoselective, and their course can be predicted by assuming a dominant stereoelectronic control of the reaction. Formation of the carbocationic intermediates 11 from 4 and 12 from 5, e.g., takes place only if the dissociating O—C bond is antiperiplanar to the donor C(β)—Fe bond. Fast H-transfer then converts the intermediate 11 to 9 and 12 to 10. The configurations of 17 and 20 can be deduced from the structure of 22 and those of 18 and 21 from that of 23. An X-ray structure determination of (1R,4S)camphanoate (-)-13 derived from alcohol (-)-7 confirms the configuration of 5 deduced above, The structures of the complexes 9 and 10, 22 and 23 were determined by their unique NMR spectra. The diastereoisomeric complexes 6 and 7 have been synthesized from aldehyde 8 with MeMgI, the diastereoisomers 17 and 18 analogously from 16 or from methyl ketone 19 by reduction with LiAlH4. Optically active starting materials (+)-1, (-)-13, (+)-20, and (+)-21 gave, by ionic hydrogenation, the complexes (-)-(3R)-3, (+)-(2S,4S)-10, (-)-(R,R, S)-22, and (-)-(R,R,R)-23 respectively, with known absolute configurations.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19900730809
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