Catalytic Asymmetric Synthesis of <i>anti</i>-α,β-Diamino Acid Derivatives
作者:Sanae Izumi、Yusuke Kobayashi、Yoshiji Takemoto
DOI:10.1021/acs.orglett.5b03666
日期:2016.2.19
A novel approach to chiral anti-α,β-diamino acid derivatives through tandem orthogonal organocatalysis has been developed. Chiral phosphoric acid catalysts control the chemo-, regio-, and stereoselective addition of hydroxylamines to alkylideneoxazolones, while a phosphine catalyst promotes the isomerization of Z- alkylideneoxazolones to the more reactive E- alkylideneoxazolones.
Practical Preparation of <i>Z</i>‐α‐(<i>N</i>‐Acetylamino)‐ and <i>Z</i>‐α‐(<i>N</i>‐Benzoylamino)‐α,β‐unsaturated Acids
作者:Branko S. Jursic、Sarada Sagiraju、Dustin K. Ancalade、Traneil Clark、Edwin D. Stevens
DOI:10.1080/00397910701265895
日期:2007.5.1
An efficient two‐step synthetic procedure for the preparation of numerous variations of N‐protected α,β‐unsaturated α‐amino acids and their corresponding esters from N‐protected glycine and either aliphatic or aromatic aldehydes was developed. The reaction involved cyclization of the N‐protected glycine into oxazolone, condensation with the aldehyde, and ring opening with a base.
摘要 开发了一种有效的两步合成程序,用于从 N-保护的甘氨酸和脂肪族或芳香族醛制备 N-保护的 α,β-不饱和 α-氨基酸及其相应的酯的多种变体。该反应包括将 N 保护的甘氨酸环化为恶唑酮、与醛缩合以及与碱开环。
The Role of the Amino Protecting Group during Parahydrogenation of Protected Dehydroamino Acids
A series of dehydroamino acids endowed with different protective groups at the amino and carboxylate moieties and with different substituents at the double bond have been reacted with parahydrogen. The observed ParaHydrogen Induced Polarization (PHIP) effects in the 1H NMR spectra are strongly dependent on the aminoprotectinggroup. DFT calculations allowed us to establish a relationship between the
使在氨基和羧酸酯部分具有不同保护基并且在双键具有不同取代基的一系列脱氢氨基酸与对氢反应。在1 H NMR光谱中观察到的副氢诱导极化(PHIP)效应强烈依赖于氨基保护基。DFT计算使我们能够建立反应中间体的结构(其能量取决于酰胺取代基)与观察到的PHIP模式之间的关系。
Syntheses of Chroman-2-ones and α-Amino Acids through a Diastereoselective Domino Reaction
作者:D. Balaji Chandrasekhar、Shwu-Chen Tsay、Tapan K. Pradhan、Jih Ru Hwu
DOI:10.1021/acs.joc.7b00260
日期:2017.6.2
Further deprotection of these isolated compounds by use of hydrochloric acid (12 N) in methanol afforded the desired free amino acids in 80–88% yields. Under these optimized conditions, epimerization did not occur at the α carbons of α-(N-benzoyl)- and free α-aminoacids. These new findings provide a convenient way to generate 3,4-disubtituted chroman-2-ones and β,β-diarylalanine derivatives with very high
5(4H)-oxazolones. Part XIII. A new synthesis of 4-ylidene-5(4H)-oxazolones by the Stille reaction
作者:Egle Maria Beccalli、Francesca Clerici、Maria Luisa Gelmi
DOI:10.1016/s0040-4020(98)01070-9
日期:1999.1
4-Chloromethylene-2-phenyl-5(4H)-oxazolone 1 was used as the starting material for the preparation of a series of 4-ylideneoxazolones 3 by the Stille reaction. When compound 1 was reacted with organostannanes 2 in the presence of the palladium catalyst, oxazolones 3 were obtained in good yields in mild reaction conditions.