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‐Alkylation of α‐Amino Esters and Amides through Hydrogen Borrowing
作者:Charlotte E. Coomber、Louis J. Diorazio
DOI:10.1002/ejoc.202200152
日期:2022.8.26
A method for the iridium catalysed direct alkylation of amino esters and amides using alcohols, which can utilise both the free base and HCl salts of the amine, was developed. This reaction proceeds through a borrowing hydrogen borrowing mechanism.
Proline Ester Enolate Claisen Rearrangement and Formal Total Synthesis of (−)-Cephalotaxine
作者:Hongjun Jeon、Yundong Chung、Sanghee Kim
DOI:10.1021/acs.joc.9b00933
日期:2019.6.21
A concise formal total synthesis of (−)-cephalotaxine was achieved via an esterenolate Claisen rearrangement (EECR). A series of EECRs of proline allyl esters were examined to obtain the desired relative stereochemistry of an azaspiranic tetracyclic backbone. An unexpected reversal or low diastereoselectivity of (Z)-cinnamyl ester was observed. The diastereoselectivity was controlled by substitution