90646-78-9Relevant academic research and scientific papers
Enzymatic Cross-Benzoin-Type Condensation of Aliphatic Aldehydes: Enantioselective Synthesis of 1-Alkyl-1-hydroxypropan-2-ones and 1-Alkyl-1-hydroxybutan-2-ones
Di Carmine, Graziano,Bortolini, Olga,Massi, Alessandro,Müller, Michael,Bernacchia, Giovanni,Fantin, Giancarlo,Ragno, Daniele,Giovannini, Pier Paolo
supporting information, p. 4132 - 4141 (2018/09/12)
Benzoin-type reactions have been intensively exploited as a synthetic strategy for the preparation of α-hydroxy ketones. Thiamine diphosphate (ThDP) dependent enzymes are excellent catalysts for asymmetric versions of such reaction types. In particular, in cross-benzoin condensations of aromatic reactants and mixed aromatic/aliphatic reactions, use of these enzymes has resulted in high levels of chemo-, regio- and stereoselectivity. The present work, which confirms this trend for aliphatic reactants, outlines results obtained in the formal cross-benzoin-type condensation of the ‘umpoled’ acetaldehyde and propionaldehyde with various aliphatic aldehydes catalyzed by the ThDP-dependent enzyme acetoin:dichlorophenolindophenol oxidoreductase (Ao:DCPIP OR). In these reactions, 3-hydroxy-3-methylbutan-2-one (methylacetoin) was used as the activated acetaldehyde donor, while 4-hydroxy-4-methylhexan-3-one was employed for the first time as the precursor of activated propionaldehyde. With the exception of 3-hydroxypentan-2-one and 3-hydroxyhexan-2-one, which were obtained in almost racemic form by the condensation of methylacetoin with propanal and butanal, respectively, all other products achieved from reactions performed using the same donor with more hindered aldehyde acceptors were obtained with high conversions (89–99%) and in good to high enantiomeric excess (72–99% ee). In a similar way, high conversions (75–99%) and good ee (76–99%) were observed in reactions performed with the same set of aldehyde acceptors, but using 4-hydroxy-4-methylhexan-3-one as propionyl anion donor. This is the first time that most of the products described herein have been prepared via benzoin-type condensation. (Figure presented.).
Convenient Synthesis of Functionalized Dialkyl Ketones and Alkanoylsilanes: 1-(Benzotriazol-1-yl)-1-phenoxyalkanes as Alkanoyl Anion Equivalents
Katritzky, Alan R.,Lang, Hengyuan,Wang, Zuoquan,Lie, Zhu
, p. 7551 - 7557 (2007/10/03)
(Benzotriazol-1-yl)-1-phenoxyalkanes 10, prepared by two-step transformations of the corresponding aldehydes, are readily deprotonated at the methine group by BuLi.Subsequent reactions with alkyl halides, aldehydes, ketones, and imines yield the corresponding substituted derivatives that undergo hydrolysis under acidic conditions to afford the expected functionalized ketones 13, 15, 17, 19, 21, 24 and 25.Two successive lithiations of (benzotriazolyl)phenoxymethane, each followed by reaction with a trialkylsilyl chloride, alkyl halide, aldehyde, or ketone, generate similar intermediates 27, 39, 31, 33, and 36.Subsequent hydrolyses of 27, 29, 31, 33, and 36 yield the functionalized ketones 28, 30, and 32 and the alkanoylsilanes 34 and 37 in good yields.
