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.
[GRAPHICS]A practical synthesis of porphobilinogen based on the biosynthetic mechanism is described. The crossed Mukayiama. aldol reaction is the key step creating the central carbon-carbon bond between the two protected forms of 5-aminolevulinic acids. The optimized sequence gives a crystalline, storable precursor, which can be transformed in high yield into porphobilinogen and bioconjugates thereof. The enzymatic hydrolysis of the precursor produces porphobilinogen in quantitative yield.