Use of Enantioselective Aldol Condensations: Efforts Directed Towards the Total Synthesis of Ionomycin

• Main Author: Shih, Thomas Loong
• Format: Others
• Language: en
• Published: 1984
• Online Access: https://thesis.library.caltech.edu/11237/1/Shih_TL_1984.pdf; Shih, Thomas Loong (1984) Use of Enantioselective Aldol Condensations: Efforts Directed Towards the Total Synthesis of Ionomycin. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/vhx3-s283. https://resolver.caltech.edu/CaltechTHESIS:10192018-103740684 <https://resolver.caltech.edu/CaltechTHESIS:10192018-103740684>

<p>The amino acid derived N-acyl oxazolidones were found to be excellent chiral enolate synthons in the aldol condensation. The dialkylboron enolates of these imides exhibit very high levels of asymmetric induction and diastereoselection. However, the use of N-acetyl oxazolidones resulted in much lower diastereoselection. In these cases, substitution of N-acetyl oxazolidones with N-α-thiomethylacetyl oxazolidones (followed by Raney Nickel desulfurization) restored the high level of stereoselection.</p> <p>Application of this methodology to the total synthesis of ionomycin is described.</p>