88002-15-7Relevant articles and documents
Selective Formation of Functionalized α-Quaternary Malononitriles toward 5,5-Disubstituted Pyrrolopyrimidinones
Whitehead, Alan,Zhang, Yong,McCabe Dunn, Jamie,Sherer, Edward C.,Lam, Yu-Hong,Stelmach, John,Sun, Aaron,Shiroda, Melisa,Orr, Robert K.,Waddell, Sherman T.,Raghavan, Subharekha
supporting information, p. 4448 - 4451 (2017/09/11)
A modular, selective approach to complex α-tertiary substituted malononitriles is reported. The method takes advantage of β-ester-substituted α,α-dinitrile alkenes as highly reactive, chemoselective electrophiles for 1,4-additions with organometallic nucleophiles to produce functionally and sterically dense all-carbon quaternary centers. In the presence of a chiral ester auxiliary bearing an aromatic ring, the 1,4-addition occurs with good to excellent selectivity due to favorable cation-π interactions. The highly functionalized malononitriles represent versatile building blocks and can be applied toward efficient, highly selective syntheses of 5,5-disubstituted pyrrolopyrimidinones.
Diatereoselectivity in the O-H Insertion Reactions of Rhodium Carbenoids Derived from Phenyldiazoacetates of Chiral Alcohols. Preparation of α-Hydroxy and α-Alkoxy Esters
Aller, Enrique,Brown, David S.,Cox, Geoffrey G.,Miller, David J.,Moody, Christopher J.
, p. 4449 - 4460 (2007/10/02)
A series of phenyldiazoacetates 3 derived from enantiomerically pure alcohols ((-)-borneol, (+)-menthol, (-)-menthol, (-)-8-phenylmenthol, (-)-trans-2-phenylcyclohexanol, (+)-trans-2-phenyl-cyclohexanol, and (-)-10-(dicyclohexylsulfamoyl)-D-isoborneol) were prepared from the corresponding α-keto esters 1 by way of the tosylhydrazones 2.Rhodium(II)-catalyzed decomposition of the diazoacetates 3 in the presence of water or alcohols resulted in carbenoid O-H insertion reactions to give the corresponding 2-hydroxy- or 2-alkoxyphenylacetates in good yield, but with varying degrees of diastereoselectivity.A range of rhodium(II) and other metal catalysts were investigated, with rhodium(II) acetate and rhodium(II) acetamide giving the best results.The stereochemistry of the major diastereomer was proved in most cases by independent synthesis from a mandelic acid derivative of known configuration.Possible mechanisms are discussed.
Asymmetric Reactions of 8-Phenylmenthyl Pyruvate with Allyltrimethylsilane, Silyl Enol Ethers and Ketene Silyl Acetals
Chen, Ming-Yi,Fang, Jim-Min
, p. 1737 - 1742 (2007/10/02)
By mediation of TiCl4, allylsilane, silyl enol ethers and ketene silyl acetals attacked (-)-phenylmenthyl pyruvate and (-)-phenylmenthyl phenylglyoxylate at their si-faces.The reactions are hypothesised to proceed with rigid cyclic transition states: anti aldol adducts 16 and 17a were favourably obtained from E-ketene silyl acetals 6 and 7 having E-configuration, whereas syn aldol adducts 18b-21b were predominantly obtained from Z-ketene silyl acetal 18 and Z-silyl enol ethers 19-21.