N-Heterocyclic carbene-catalyzed formal cross-coupling reaction of α-haloenals with thiols: organocatalytic construction of sp2 carbon–sulfur bonds
作者:Lin He、Hao Guo、Yuan-Zhen Li、Guang-Fen Du、Bin Dai
DOI:10.1039/c4cc00154k
日期:——
A novel N-heterocyclic carbene (NHC)-catalyzed formal cross-coupling reaction between α-haloenals and thiols was developed. In the presence of 5 mol% NHC precursors and 1.6 equiv. potassium carbonate, various thiols coupled with α-haloenals to produce α-thioenals in 53% to 91% yield and excellent Z-selectivity.
Palladium catalysed formal 6-endo-trig approaches to pumiliotoxin alkaloids: interception of the elusive cyclopropyl intermediate
作者:Stephanie Feutren、Helena McAlonan、David Montgomery、Paul J. Stevenson
DOI:10.1039/a909774k
日期:——
Intramolecular Heck cyclisation of (E)-vinyl bromides leads to indolizidines, related to pumiliotoxin alkaloids, in which the stereochemistry of the trisubstituted double bond undergoes inversion. A cyclopropyl intermediate, which is believed to be responsible for the double bond inversion, has been intercepted by forcing an ‘early’ β-hydride elimination on this species. The relative stereochemistry
N-Heterocyclic Carbene-Catalyzed Aza-Michael–Mannich–Lactamization Cascade for the Enantioselective Synthesis of Pyrazoloquinolin-3-ones
作者:Sayan Shee、Deeptanu Sarkar、Akkattu T. Biju
DOI:10.1021/acs.orglett.2c04070
日期:2023.1.13
aza-Michael–Mannich–lactamization sequence to afford the tricyclic products bearing three contiguous stereocenters, including a stericallydemanding quaternary stereocenter with high enantioselectivity. The unprotected amine-triggered aza-Michael pathway over the competing amidation pathway is noteworthy.
Synthesis of chiral α‐amino ketones via TM‐ or photoredox coupling and olefin photo‐cleavage reaction sequence
作者:Dominika Kobus-Bartoszewicz、Sebastian Stecko
DOI:10.1002/adsc.202300055
日期:——
We report a convenient two-step approach to α-amino ketones involving cross-coupling and oxidative cleavage sequence. The cross-coupling reaction creates a divergent functionalization of the molecular platform, e. g., N-(2-bromoallyl)amine, whereas the oxidative cleavage establishes the carbonyl functionality. This strategy allows for an introduction of aryl/heteroaryl and alkyl groups, either through
A chiral carbene-catalyzed chemo- and enantioselective reaction with racemic biaryl aldehydes and α-bromoenals is developed for access to axially chiral 2-arylbenzaldehydes through atroposelective dynamic kinetic resolution (DKR) processes. This atroposelective DKR strategy can tolerate a broad scope of substrates with diverse functionalities. The axially chiral 2-aryl benzaldehyde products generally