This article describes the total synthesis of seven porphyrins, fossils of chlorophyll derivatives, isolated from sedimentary sources and possess five-membered rings fused to the porphyrin nucleus, this additional ring being placed between positions 13,15 or 15,17. This ring was built from vinyl, hydroxyethyl or isopropenyl groups under strong acidic conditions.
Porphyrins with exocyclic rings. Part 22: Synthesis of deoxophylloerythroetioporphyrin (DPEP), three ring homologues, and five related nonpolar bacteriopetroporphyrins using a western ring closure and an improved b-bilene methodology
作者:Timothy D. Lash、Wei Li、Desiree M. Quizon-Colquitt
DOI:10.1016/j.tet.2007.09.059
日期:2007.12
carbaldehydes under mildly acidic conditions. Following deprotection of the terminal ester groups, cyclization with TFA–CH(OMe)3 gave a series of ringhomologues of deoxophylloerythroetioporphyrin (DPEP). The b-bilenes generated from the five-membered ring dipyrroles proved to be rather unstable and had to be used directly without purification. Cyclization gave DPEP contaminated with an etioporphyrin by-product
含有五元碳环的二吡咯中间体很容易从环戊[ b ]吡咯制备,该单元代表在富含机油的沉积物(如油页岩和石油)中发现的DPEP型地卟啉的南半部分。当在温和的酸性条件下与二吡咯甲烷甲醛反应时,具有六元,七元或八元碳环的相关二吡咯显示出b- ene。末端酯基脱保护后,用TFA-CH(OMe)3环化得到一系列的脱氧叶绿体铁卟啉(DPEP)环同系物。在b由五元环二吡咯生成的β-二烯被证明是相当不稳定的,必须不经纯化直接使用。环化产生DPEP并被埃菲卟啉副产物污染,但可以通过快速色谱法将其分离为镍(II)衍生物。与先前报道的方法相比,该方法可产生更高的DPEP产量。另外,该方法可以扩展到相关的卟啉的合成,并且通过这种方法合成了由细菌叶绿素d衍生的一系列五种分子化石。