Simple Understanding of Samarium Fluoride SmF3
Samarium Fluoride SmF3 and paclitaxel were successfully synthesized at -78°C with a yield of 70% and a stereoselectivity greater than 4:1. It occupies four carbon atoms in an octahedral ring, and has a novel structure, which is difficult to synthesize. Using SMLZ, Molander successfully constructed the octagonal backbone "3" of (-)-steganone. Moran also used Samarium Fluoride SmF3 in the synthesis of the (-)-cryptone analogue (+)-isoschisandrol.
The axial chirality of compound 14 effectively controls the chirality of the product, and the Z-type double bond also plays an important role in the reaction. The complexes of HMPA and SML form calcium alkoxides in the saddle oxygen reaction system. Several complexes of HMPA with SM increase their bulk, effectively controlling the configuration of the transition state. Oxygen cyclization is notoriously strong affinity.
Due to the complex between Samarium Fluoride SmF3, the smlz-mediated intramolecular cyclization of pinacol tends to generate cis-diols. If there is an alkoxy substituent at the alpha position, the newly formed majority of these reaction products are in the opposite direction to the original alkoxy group.
In the synthesis of paclitaxel octahedral skeleton, the intramolecular cyclization reaction of pinacol mediated by Samarium Fluoride SmF3 was used. It was shown that the newly formed diol in the product was trans. It is well known that the stable conformation of the octane ring is the chair type, and Samarium Fluoride SmF3 suggested that the formation of trans diols should be attributed to the transition state structure of similar products.