Development of Useful Reactions Involving Tandem Cyclizations Based on the Novel Reactivities of Allenic Compounds

Synthesis and Applications of Vinylaziridines and Ethynylaziridines

“…Although the transition-metal-catalyzed cyclization of amino allenes to form five- and six-membered azacycles has been widely investigated, the formation of aziridines according to this strategy remained unprecedented until 1999. Ibuka, Ohno, and co-workers reported that the palladium-catalyzed reaction of α-amino allene 121 with iodobenzene in the presence of K 2 CO 3 in 1,4-dioxane afforded the corresponding vinylaziridines 123 bearing a phenyl group on the double bond exclusively (Scheme ).…”

Phosphine‐Free Palladium‐Catalyzed Allene Carbopalladation/Allylic Alkylation Domino Sequence: A New Route to 4‐(α‐Styryl) γ‐Lactams

“…As dba is known to be a non-innocent ligand, [12] a dba-free system was also studied. Accordingly, a phosphine-free Pd 0 complex was generated in DMSO from 2 ], by using nBuLi (2 equiv) as an in situ reducing agent. [13] The desired product was obtained in 90 % yield, thereby demonstrating the catalytic efficiency of this phosphine-free system (Table 1, entry 13).…”

“…[c] 2 /dppf THF 64 38 4 [d] PdA C H T U N G T R E N N U N G (OAc) 2 /dppf THF 100 58 5 [e] PdA C H T U N G T R E N N U N G (OAc) 2 /dppf THF 100 64 6 [e] PdA C H T U N G T R E N N U N G (OAc) 2 /dppf 1,4-dioxane 100 58 7 [e] PdA C H T U N G T R E N N U N G (OAc) 2 /dppf toluene 100 28 8 [e] PdA C H T U N G T R E N N U N G (OAc) 2 PdA C H T U N G T R E N N U N G (OAc) 2 /dppf DMF 100 76 11 [e] PdA C H T U N G T R E N N U N G (OAc) 2 /dppf DMSO 100 88 12 In conclusion, we have developed a phosphine-free carbopalladation/allylic alkylation sequence allowing the synthesis of 4-(a-styryl) g-lactams. High yields were obtained for electron-rich as well as electron-poor aryl iodides.…”

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Dedicated to our friend and colleague Professor Max Malacria on the occasion of his 60th birthdayIn recent decades, allene chemistry has gained a tremendous importance, in particular in the field of transitionmetal catalysis.[1] Effective and straightforward methods for the synthesis of carbo-and heterocycles have emerged, [2] due to the unique reactivity of allenes toward arylpalladium species. Indeed, the carbopalladation of a 1,2-diene takes place regioselectively, generating a transient p-allyl intermediate, [3] which can in turn be trapped by an internal nucleophile.

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