A Concise Synthesis of
<i>rac</i>
‐
<i>Ambrox</i>
®
<i>via</i>
the Palladium(0)‐Catalyzed Carboalkoxylation of an Allylic Ammonium Salt, as Compared to a Formaldehyde Hetero
<i>Diels–Alder</i>
Approach
作者:Christian Chapuis、David Skuy、Claude‐Alain Richard
DOI:10.1002/hlca.201900097
日期:2019.7
followed by a 1.5 mol‐% Pd‐catalyzed carbomethoxylation of quaternized 31b, leads to the methyl ester 36a. This latter could also be obtained in optically pure form by carbomethoxylation of the corresponding (+)‐acetate. Final reduction‐cyclization may be conducted as earlier described, towards the desired odoriferous rac‐Ambrox® 38a, or its pure (−)‐enantiomer. Generation of a π‐allyl Pd complex from an allylic