modification of these porphyrins with moieties inducing biological activity. Modification of the tetrapyrroles may occur by addition to one of the porphyrin peripheral double bonds, the use of substituents of the arylgroups or via the methoxycarbonyl group at two of the meso‐substituents. Three examples of porphyrins were converted into the corresponding 7,8‐dihydroxychlorins by osmium‐mediated dihydroxylation
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。
Ring cleaving selenenylation and sulfenylation of cyclopropane derivatives promoted by TiCl4
作者:Hans-Ulrich Reissig、Ingrid Reichelt
DOI:10.1016/s0040-4039(01)81709-3
日期:1984.1
A synthesis of 2-selenenyl and sulfenyl 4-oxoesters based on Lewis acid promoted activation of methyl 2-trimethylsiloxy cyclopropanecarboxylates is reported. A mechanistic scheme for this new C-Se and C-S forming reaction is disclosed.
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.
Low temperature equilibration of cyclopropanes by Lewis acid catalysis
作者:Hans-Ulrich Reissig、Ingrid Böhm
DOI:10.1016/s0040-4039(00)81506-3
日期:1983.1
Under the influence of Lewis acids the cis/trans-equilibration of methyl 2-trimethyl-siloxy cyclopropanecarboxylates occurs even at −78°C. It involves the heterolytic cleavage of a CC bond and seems to be governed by steric effects.
Lewis acid promoted additions of cyclopropanes to iminium salts: a new possibility for α-methylene-γ-butyrolactone synthesis
作者:Hans-Ulrich Reissig、Hiltrud Lorey
DOI:10.1039/c39860000269
日期:——
Methyl 2-siloxycyclopropanecarboxylates (1) smoothly add to dimethylmethyleneammonium trifluoromethanesulphonate, generated in situ, or to the corresponding minium chloride (4) in the presence of TiCl4, giving α-aminomethylated γ-oxoesters (6) in good yield; these can serve as precursors for α-methylene-γ-butyrolactones (7) as well as for acrylic ester derivatives (8).