Controlling stereochemistry in polyketide synthesis: 1,3- vs. 1,2-asymmetric induction in methyl ketone aldol additions to β-super siloxy aldehydes
作者:Patrick B. Brady、Brian J. Albert、Matsujiro Akakura、Hisashi Yamamoto
DOI:10.1039/c3sc51183a
日期:——
The aldol addition of methyl ketones to β-siloxy and α-methyl β-siloxy aldehydes is described. Careful control of mechanistically distinct aldol reactions leverages 1,2- and 1,3-asymmetric induction, selectively forming syn and anti aldol adducts with excellent diastereocontrol. Experimental and theoretical investigations have provided insight to the factors governing diastereoselectivity.
Rapid Total Syntheses Utilizing “Supersilyl” Chemistry
作者:Brian J. Albert、Yousuke Yamaoka、Hisashi Yamamoto
DOI:10.1002/anie.201007210
日期:2011.3.7
In short order: The shortest total syntheses of natural product EBC‐23 (see scheme, PMB=para‐methoxybenzyl, TMS=trimethylsilyl) and a polymethoxy‐1‐alkene to date have been accomplished in just ten total steps each from commercially available chemicals. The syntheses took advantage of highly diastereoselective supersilyl‐directed cascade polyaldol reactions.
Super Silyl Stereo-Directing Groups for Complete 1,5-Syn and -Anti Stereoselectivities in the Aldol Reactions of β-Siloxy Methyl Ketones with Aldehydes
作者:Yousuke Yamaoka、Hisashi Yamamoto
DOI:10.1021/ja101076q
日期:2010.4.21
-anti stereoinduction in the aldol reaction of beta-tris(trialkylsilyl)siloxy methylketones can be achieved with high diastereoselectivities. Tris(trialkylsilyl)silyl groups are easily prepared and play an important role in the selectivities of these reactions. Furthermore, all of the 1,3,5-triol stereoisomers can easily be prepared from beta-siloxy methylketones in no more than three steps.