HBr–DMPU: The First Aprotic Organic Solution of Hydrogen Bromide
作者:Zhou Li、Rene Ebule、Jessica Kostyo、Gerald B. Hammond、Bo Xu
DOI:10.1002/chem.201703457
日期:2017.9.18
HBr and DMPU (1,3‐dimethyl‐3,4,5,6‐tetrahydro‐2‐pyrimidinone) form a room‐temperature‐stable complex that provides a mild, effective, and selective hydrobrominating reagent toward alkynes, alkenes, and allenes. HBr–DMPU could also replace other halogenating reagents in the halo‐Prins reaction, ether cleavage, and deoxy‐bromination reactions.
Vinyl chlorides and bromides are obtained in good yield from the corresponding ketones and acetylhalides in the presence of trifluoroacetic or trifluoromethanesulfonic acid. The Z isomer is selectively formed.
Palladium(0)-catalyzed [2 + 2 + 1] cyclization of 1,6-enynes with vinyl bromides: a highly diastereoselective synthesis of tetrahydro-1H-cyclopenta[c]furans bearing two quaternary carbon centers
A new cascade process has been accomplished for the synthesis of terahydro-1H-cyclopenta[c]furans through palladium-catalyzed [2+2+1] cyclization of 1,6-enynes with vinyl bromides. Notably, the key feature of this transformation is the use of vinyl bromides as the C1 building block. Various functionalized tetrahydro-1H-cyclopenta[c]furans bearing two quaternary carbon centers could be obtained in good
Cascade reactions are an important strategy in reaction design, allowing streamlining of chemical synthesis. Here we report a cascade Suzuki–Miyaura/Diels–Alder reaction, employing vinyl Bpin as a bifunctional reagent in two distinct roles: as an organoboron nucleophile for cross-coupling and as a Diels–Alder dienophile. Merging these two reactionsenables a rapid and operationally simple synthesis
In the presence of titanium tetraiodide, a tandem Prins reaction of alkynes proceeded with acetals to give (Z,Z)-1,5-diiodo-1,3,5-triarylpenta-1,4-dienes in good yields, where an intriguing reversal of the stereoselectivity was observed among titanium tetrahalides.