带有特定取代基模式的中观取代的反式A 2 B 2卟啉是基于卟啉的仿生系统和分子材料的关键组成部分,可用于构建定义明确的基于卟啉的体系结构。逐步和合理合成功能化反式A 2 B 2的新方法报道了卟啉,其中首次利用了供体-受体取代的环丙烷前体(d-a环丙烷)。所提供的三种d-a环丙烷很容易以克数形式获得,并且在与过量吡咯的反应中用作醛当量,以提供相应的二吡咯甲烷(DPM)。合成了三种DPM,产率为60-74%。它们在没有光和空气的情况下以纯化形式稳定,随后与各种带有给电子或吸电子取代基的脂族和芳族醛缩合,然后氧化形成相应的反式-A 2 B 2。卟啉。合成了14种功能化的卟啉,产率为14-31%,表明合成方法的范围很广。强调了引入关键官能团的可能性,其使得随后的这些卟啉具有诱导生物活性的部分的修饰。可以通过添加一个卟啉外围双键,使用芳基的取代基或通过两个内消旋基上的甲氧羰基进行四吡咯的修饰取代基。
A new multicomponent synthesis of 2-aminothiophene carbocyclic acids 4 by reaction of methyl 2-siloxycyclopropane-carboxylates 1, alkyl cyanoacetates, and elemental sulfur is reported. This version of the Gewald thiophene synthesis rapidly provides a new type of δ-amino acids, which can be considered as dipeptide analogues. Smooth protective-group manipulations allowed regio- and chemoselective couplings with l-phenylalanine derivatives furnishing new tripeptide analogues such as 5 and 8 or products of type 10.
Trifluoromethanesulfonicacid in acetonitrile was found to efficiently catalyze Friedel–Crafts alkylations of 1,2,4-trimethoxybenzene with a variety of simple or functionalized aldehydes to provide di- or triarylmethanes in high yields. The operationally simple protocol allowed a short synthesis of the phenylpropanoid natural product (−)-tatarinoid C establishing its absolute configuration. Under the
A novel rearrangement leading to methoxycarbonylmethylated silyl enol ethers
作者:Hans-Ulrich Reissig
DOI:10.1016/s0040-4039(00)98693-3
日期:1985.1
Methyl 2-siloxycyclopropanecarboxylates rearrange smoothly and quantitatively to the corresponding silylenolethers (3) by addition of a catalytical amount of iodo trimethylsilane. Scope and limitation of this novelprocess as well as the synthesis of the electron rich diene (10a) are described.
Reaction of methyl trimethylsiloxycyclopropanecarboxylates 3 with amino acids, tert-butylisonitrile and methanol furnished amino diacid derivatives 2 as the result of an Ugi 5-center 4-component reaction. This one-pot reaction involves β-formyl esters such as 1 as intermediate, which are liberated in situ. Adducts 2 could be thermally cyclized to provide γ-lactams 4 in good yields. The multi component reaction was combined with this cyclization process to a fairly efficient one-pot procedure. Thus, cyclopropane derivative 3a was converted into γ-lactam 4a in good yield. Two of the γ-lactams 4 were reduced with lithium aluminum hydride to give pyrrolidine derivatives 5. Based on an X-ray analysis of the major diastereomer of compound 5d, the diastereoselectivity of the 4-component reaction is discussed.
New Macrocyclic Peptidomimetics Containing 5-Aminothiophene Subunits
作者:Hülya Özbek、Dieter Lentz、Hans-Ulrich Reissig
DOI:10.1002/ejoc.201001066
日期:2010.11
The synthesis of a new class of cyclic peptidomimeticscontaining5-aminothiophenesubunits in their backbone is presented. A modified Gewald reaction was applied as a key step in the synthesis of the thiophene amino acid that was used as a building block in the synthesis of linear oligomers by using standard peptide coupling protocols. Macrocyclization was achieved under high dilution by using EDCI
介绍了在其骨架中含有 5-氨基噻吩亚基的一类新环状肽模拟物的合成。改进的 Gewald 反应被用作合成噻吩氨基酸的关键步骤,噻吩氨基酸在使用标准肽偶联方案合成线性寡聚体时用作结构单元。通过使用 EDCI 作为偶联剂在高度稀释下实现大环化。无环二聚体和环状四聚体的构象通过 X 射线晶体学分析确定。