Lewis Base-Catalyzed Interhalogenation of Terminal Allenes: Selective Strategy for Accessing Vicinal Vinylic, Allylic Heterodihalides

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: March 28, 2025

Though precedent remains limited, the selective interhalogenation of allenes offers a valuable synthetic strategy to access products where each halide exhibits orthogonal reactivity. Here, we describe Lewis base-catalyzed approach for dihalogenation (bromochlorination, iodochlorination, iodobromination, and dibromination) terminal allenes. By employing just 1 mol % triphenylphosphine oxide or hexamethylphosphoramide activate thionyl halides in presence electrophilic halogenation reagents, achieve conversion monosubstituted vicinal allylic, vinylic dihalides with up 93% yield >20:1 regioisomeric ratio, favoring branched dihalogenated product. A range functional groups is tolerated, including nitrile, ester, phosphate, sulfonamide, silyl groups, reaction proved be scalable. The utility various dihalide was investigated substitution cross-coupling chemistry, highlighting distinct reactivity among different classes.

Language: Английский

Electrochemical Cyclization of 2,3-Allenols

Organic Letters, Journal Year: 2025, Volume and Issue: unknown

Published: April 3, 2025

An efficient electrochemical bromocyclization of allenols has been realized for the synthesis spirocyclic 2,5-dihydrofurans. The reaction used commercially available and nontoxic KBr as brominating source in a simple setup under open-air conditions. Notably, optically active products can be obtained from 2,3-allenols without any racemization, further enhancing synthetic utility.

Language: Английский