Diazabutadienes in heterocyclic syntheses. Preparation of pyrimidin-6-ones by reaction of 4-dialkylamino-1,3-diaza-1,3-butadienes with 2-oxazolin-5-ones
作者:Bir Sain、Satyendra P. Singh、Jagir S. Sandhu
DOI:10.1016/s0040-4020(01)81230-8
日期:1992.1
1-aryl-4-dimethylamino-2-methylthio-1,3-diaza-1,3-butadienes ( reacted with 2-oxazolin-5-ones () to yield pyrimidin-6-ones () and () respectively as single diastereoisomers with reverse stereochemistry. Reaction of 1,2-diphenyl-4-methylthio-4-amino-1,3-diaza-1,3-butadienes () with () also yielded pyrimidin-6-ones ().
The first example of the readily scalable direct allylic alkylation of azlactones with simple allylic alcohols has been developed, which is catalyzed by Pd(PPh3)4 alone in the absence of any activators under neutral conditions.
quaternary amino acidderivatives from inexpensive bulk chemicals. In that way highly enantioenriched acyclic α‐amino acids, α‐alkyl proline, and α‐alkyl pyroglutamic acidderivatives could be prepared in diastereomerically pure form. In addition, a unique way is presented to prepare diastereomerically pure bicyclic dipeptides in just two steps from unprotected tertiary α‐amino acids.
描述了作为活化氨基酸衍生物的氮杂内酯的第一次催化不对称共轭加成反应向烯酮的发展和进一步发展。第一代方法是从孤立的氮杂内酯开始的,而第二代方法中的氮杂内酯可以从外消旋的N开始原位生成。苯甲酰化氨基酸。第三个进化阶段可以利用外消旋未保护的α-氨基酸直接形成高度对映体富集和非对映体纯的带掩蔽季铵氨基酸产物,并带有一个附加的叔立体中心。通过使用稳固的平面手性bis-Pd催化剂,布朗斯台德酸(HOAc或BzOH; Ac =乙酰基,Bz =苯甲酰基)和布朗斯台德碱(NaOAc),通过协同活化来实现逐步经济转型。特别是第二代和第三代方法提供了快速而多样化的途径,可从廉价的散装化学品中获得生物学上令人感兴趣的非天然季氨基酸衍生物。这样,可以以非对映体纯形式制备高度对映体富集的无环α-氨基酸,α-烷基脯氨酸和α-烷基焦谷氨酸衍生物。此外,
Gold(I)-Catalyzed Diastereo- and Enantioselective 1,3-Dipolar Cycloaddition and Mannich Reactions of Azlactones
作者:Asa D. Melhado、Giovanni W. Amarante、Z. Jane Wang、Marco Luparia、F. Dean Toste
DOI:10.1021/ja1095045
日期:2011.3.16
reactions with electron-deficient alkenes and N-sulfonyl aldimines to give products of 1,3-dipolar cycloaddition and Mannich addition reactions, respectively. Both of these reactions proceed with good to excellent diastereo- and enantioselectivityusing a single class of gold catalysts, namely C(2)-symmetric bis(phosphinegold(I) carboxylate) complexes. The development of the azlactone Mannich reaction to
Pd-Catalyzed Asymmetric Hydroalkylation of 1,3-Dienes: Access to Unnatural α-Amino Acid Derivatives Containing Vicinal Quaternary and Tertiary Stereogenic Centers
作者:Zongpeng Zhang、Fan Xiao、Hui-Min Wu、Xiu-Qin Dong、Chun-Jiang Wang
DOI:10.1021/acs.orglett.9b04341
日期:2020.1.17
α-quaternary α-amino acid derivatives bearing contiguous quaternary and tertiarystereogeniccenters in good yields with exclusive regioselectivity and excellent stereoselective control (up to 92% yield, >20:1 dr, and >99% ee). The scale-up catalytic asymmetric hydroalkylation was performed well without loss of reactivity and stereoselectivities, which exhibited great potential application. The synthetic utility