The boraformylation of allenes with B2(pin)2 and a formate ester as boron and formyl source, respectively, proceeds in the presence of a copper catalyst. The reaction selectively affords the corresponding β‐boryl β,γ‐unsaturated aldehydes in good to high yields. Furthermore, the silaformylation of allenes was achieved with a formate ester and PhMe2Si−B(pin) as the silicon source.
Evidence for concerted processes in the course of the homoallenylic transposition
作者:Chahinez Aouf、Nicolas Galy、Maurice Santelli
DOI:10.1016/j.tet.2013.02.048
日期:2013.4
The hydrolysis of β-allenic tosylates produces mainly 2-methylenecyclobutanols resulting from a homoallenylic participation along with isomeric 2-methylenecyclobutanol minor products coming from a 1234–1243 rearrangement. Structures of various cyclopropylvinyl carbocations involved in the course of the hydrolysis have been determined by computational studies. For acyclic tosylates, the hydrolysis of
The electrophilic cyanation of allylic boranes, a process that is applicable to the construction of allylic quaternary carbon centers, is reported. The reaction has a broad substrate scope with a high functional group tolerance. The results represent an unprecedented and powerful tool for preparing synthetically useful β,γ-unsaturated nitriles, including derivatives that have been difficult to access
Solvolysis of acyclic allenic tosylates shows that the allene group participates strongly to give cyclopropyl ketones and methylenecyclobutanols. Whenever C4 and C5 of the 3-methyl penta-1,2 dien-5-yl system carry different substituents, an apparent exchange of position between them occurs during the cyclisation.
Skeletal and Mechanistic Diversity in Ir‐Catalyzed Cycloisomerizations of Allene‐Tethered Pyrroles and Indoles
作者:Andrés Arribas、Martín Calvelo、Alejandro Rey、José L. Mascareñas、Fernando López
DOI:10.1002/anie.202408258
日期:2024.9.2
An iridium-catalyzed cycloisomerization of N-allenyl pyrroles and indoles is reported. The method, which is initiated by a C−H activation step, delivers a diversity of synthetically relevant azaheterocyclic products, depending on the precise ancillary ligand used and the substitution pattern of the allene. Particularly attractive are the hydrocarbonation cascades of tetrasubstituted allenyl precursors