56346-01-1Relevant academic research and scientific papers
The reduction of α-silyloxy ketones using phenyldimethylsilyllithium
Fleming, Ian,Roberts, Richard S.,Smith, Stephen C.
, p. 1215 - 1228 (2007/10/03)
Phenyldimethylsilyllithium reacts with acyloin silyl ethers RCH(OSiMe3)COR 8 to give regiodefined silyl enol ethers RCH=C(OSiMe2Ph)R 9, and hence by hydrolysis ketones RCH2COR 10. The yields can be high but are usually moderate. The mechanism of this reduction is established to involve a Brook rearrangement (Scheme 6) rather than a Peterson elimination (Scheme 1). Although the mechanism appears to be the same in each case, the stereochemistries of the silyl enol ethers 9 are opposite in sense in the aromatic series (R = Ph, Scheme 7) and the aliphatic series (R = cyclohexyl, Scheme 8), with the major aromatic silyl enol ether being the thermodynamically less stable isomer E-PhCH=C(OSiMe2Ph)Ph E-9aa, and the major aliphatic silyl enol ether being the thermodynamically more stable isomer Z-c-C6H11CH= C(OSiMe2Ph)-c-C6H11 Z-9ba. This is a consequence of anomalous anti-Felkin attack in the aromatic series. The reaction with the silyl ether ButCH(OSiMe3)COPh 13b is normal in giving Z-ButCH= C(OSiMe2Ph)Ph Z-38 (Scheme 11), but reduction of the silyl ether 8a with lithium aluminium hydride is also anti-Felkin giving with high selectivity the meso diol PhCH(OH)CH(OH)Ph 39. The reaction between Phenyldimethylsilyllithium and the acyloin silyl ether 8d (R = But) does not give the ketone ButCH2COBut, but gives instead the anti-Felkin meso diol ButCHOHCHOHBut 40 also with high selectivity (Scheme 12). Silyllithium and some related reagents react with trifluoromethyl ketones 46 and 48 to give α,α-difluoro silyl enol ethers 47 and 49 (Scheme 14).
Trifluoromethanesulfonic (Triflic) Acid Catalyzed Transformations of α-Hydroxy Carbonyl Compounds
Olah, George A.,Wu, An-hsiang
, p. 2531 - 2534 (2007/10/02)
Triflic acid catalyzed reaction of 2-hydroxy-2-adamantanecarboxylic acid results via ionizative decarbonylation in the formation of adamantanone.Under carbon monoxide pressure pinacol-type rearrangement gives 4,5-homoadamantanedione.Reactions of a series of α-hydroxy ketones result in fragmentation, deprotonation, and cyclization, respectively.The reactions and their suggested mechanism are discussed.
