54344-89-7Relevant academic research and scientific papers
A Concise Synthesis of rac-Ambrox via the Palladium(0)-Catalyzed Carboalkoxylation of an Allylic Ammonium Salt, as Compared to a Formaldehyde Hetero Diels–Alder Approach
Chapuis, Christian,Skuy, David,Richard, Claude-Alain
, (2019/07/09)
Acidic cyclization of either the diethylallylamines 29b or 30, 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 ammonium salt, followed by carboalkoxylation is novel. In only five chemical steps starting from farnesene 2, the present work constitutes the most concise total synthesis of rac-Ambrox 38a to date.
