Enantioselective Synthesis of 3-Allylindolizines via Sequential Rh-Catalyzed Asymmetric Allylation and Tschitschibabin Reaction
The first highly regio- and enantioselective synthesis of 3-allylindolizines has been developed by the sequential Rh-catalyzed asymmetric allylation and Tschitschibabin reaction. Above the 20:1 branch/linear ratio, up to a 96% yield and 99% ee could be obtained with the help of tert-butyl-substituted chiral bisoxazolinephosphine ligand. In situ generated highly nucleophilic 2-alkylpyridinium ylides are utilized to undergo the asymmetric alkylation reaction before cyclization.
Method and composition for rejuvinating cells, tissues organs, hair and nails
In one embodiment, the present invention relates to compounds and compositions including pharmaceutical compositions containing the compounds and associated methods that uncouple sugar-mediated coupling of proteins, lipids, nucleic acids, and other biomat
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(2008/06/13)
2-Phosphaindolizines
Pyridinium bromides 3 prepared by alkylation of 2-methyl-, 2-ethyl-, and 2-benzylpyridines 1 with methyl bromides 2 bearing an electron-withdrawing group (COPh, CN, CO2Et, C6H4NO2) are condensed with PCl3 in the presence of Et3N to give 2-phosphaindolizin