ISSN:
0009-2940
Keywords:
Aldol additions
;
Michael additions
;
Nitroalkanes, fluorinated
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Aldol and Michael Additions of Fluorinated Nitroalkanes to Aldehydes, Ketones, and α,β-Unsaturated Carbonyl Compounds1,2)2,2,2-Trifluoronitroethane (1) and 3,3,3-trifluoro-2-nitropropane (2), despite their great propensity to undergo HF elimination with base, can be added to aldehydes with KF or neutral alumina (nitroaldol products 7-15). With basic alumina (neat components) they even add to α,β-unsaturated aldehydes, ketones, esters, and nitriles (γ-nitro carbonyl derivatives and nitrile 27-35). Doubly lithiated difluoro and trifluoro nitro derivatives (H, L) can be generated from the corresponding nitroethanes and -propanes (1-3) with butyllithium (THF, - 100 to -70°C) and added to aldehydes and ketones to give nitroaldols (nitroethanols 11, 12, 16-21) and “homonitroaldols” (nitropropanols 36-38). In essentially all cases, mixtures of diastereoisomers are formed. Through O-silyltrifluoronitroaldols (22-26) it is possible to enrich one of the diastereoisomers by 3:1 (Scheme 4). Some transformations of the nitro compounds obtained lead to CF3-substituted aminoethanols (39-46, by catalytic hydrogenation on Raney nickel), a nitrobutanol (30 → 48, with Et3SiH), and a ketone (30 → 49, with Bu3SnH).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911241233
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