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Palladium‐Catalyzed Tail‐to‐Tail Reductive Dimerization of Terminal Alkynes to 2,3‐Dibranched Butadienes
Ist Teil von
Angewandte Chemie International Edition, 2022-03, Vol.61 (13), p.e202116870-n/a
Auflage
International ed. in English
Ort / Verlag
Germany: Wiley Subscription Services, Inc
Erscheinungsjahr
2022
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
The palladium‐catalyzed tail‐to‐tail reductive dimerization of terminal alkynes is described for the first time. Aromatic terminal alkynes bearing diverse and sensitive functional groups as well as aliphatic terminal alkynes are efficiently transformed to 2,3‐dibranched butadienes. The key to achieve a selective tail‐to‐tail reductive dimerization reaction is to control appropriately the acidity of the reaction solution, which is accomplished by a combined use of pivalic acid and para‐toluenesulfonic acid. The tail‐to‐tail reductive dimerization reaction is proposed to proceed via a cationic alkenyl palladium intermediate under acidic conditions.
The use of a combination of pivalic acid and para‐toluenesulfonic acid proved successful in favoring the selective highly chemo‐ and regioselective tail‐to‐tail reductive dimerization of terminal alkynes over the competitive head‐to‐tail dimerization pathway. The target reaction, proposed to proceed via a cationic alkenyl palladium intermediate, presents a facile and straightforward approach for accessing 2,3‐dibranched butadienes.