De-mayo-reaktionen mit allen. Ein kurzer weg zum bicyclo[5.3.1.]undecansystem der taxane.

Harnessing the Power of the De Mayo Reaction: Unveiling a Photochemical and Photocatalytic Masked [2+2] Methodology for Organic Synthesis

“…The intermolecular reaction between a protected enol carbonate and allene has also been employed in the AB ring system of the taxane skeleton. [47] More recently, Winkler and Hiemstra reported the synthesis of bicyclic pyrrole or furan fused to eightmembered rings by the intramolecular cycloaddition of allenes with vinylogous amides or esters followed by the heteroatom-induced fragmentation (Scheme 23). [48] In 2018, Hiersemann and co-workers reported the first intramolecular alkyne analogue of the de Mayo reaction for the synthesis of annulated seven-and eight-membered rings and cyclohepta [b]indoles (Scheme 24).…”

“… [46] In this case, the [2+2] photocycloaddition results in a mixture of head‐to‐head and head‐to‐tail regioisomers that evolves to the formation of the corresponding cyclooctadienone or δ‐valerolactone respectively through spontaneous dimerization. The intermolecular reaction between a protected enol carbonate and allene has also been employed in the AB ring system of the taxane skeleton [47] …”

Palladium‐Catalyzed Synthesis of Substituted Cycloheptane‐1,4‐diones by an Asymmetric Ring‐Expanding Allylation (AREA)

“…The potential of this transformation has been demonstrated with the huge number of natural product syntheses that use the de Mayo reaction. [9][10][11] The asymmetric transition-metal-catalyzed decarboxylative allylation of ketone or b-ketoester enolates is an extremely valuable tool for the construction of stereocenters adjacent to carbonyl groups. [12,13] The reaction is broadly applicable as they generally proceed with high yields and under very mild reaction conditions.…”