Direct FeX3-Based Stereocontrolled Access to (Z)-3-Alkenyl-oxindoles from Allenols
摘要:
Iron trihalides (FeCl3 and FeBr3) smoothly promote the halogenation/rearrangement of 2-indolinone-tethered allenols to efficiently afford 3-halodienyl-oxindoles with good yield and total selectivity. Also, 2-halo-1,3-dienes are synthetically interesting building blocks for the preparation of functionalized 3-alkenyl-oxindoles through a Suzuki-Miyaura reaction.
The reactions of 3-allenyl 3-hydroxyoxindoles with a variety of halogenated reagents in the presence of catalytic amounts of precious metal salts were explored. Both, rearrangement and oxycyclization reactions to give 4-(1-halovinyl)-quinolinediones or spirocyclic halooxindoles, respectively, are competitive pathways. The kind of functionalization is substrate and reaction conditions dependent.
Iron trihalides (FeCl3 and FeBr3) smoothly promote the halogenation/rearrangement of 2-indolinone-tethered allenols to efficiently afford 3-halodienyl-oxindoles with good yield and total selectivity. Also, 2-halo-1,3-dienes are synthetically interesting building blocks for the preparation of functionalized 3-alkenyl-oxindoles through a Suzuki-Miyaura reaction.
Controlled Rearrangement of Lactam-Tethered Allenols with Brominating Reagents: A Combined Experimental and Theoretical Study on α- versus β-Keto Lactam Formation
作者:Benito Alcaide、Pedro Almendros、Amparo Luna、Sara Cembellín、Manuel Arnó、Luis R. Domingo
DOI:10.1002/chem.201101160
日期:2011.10.4
expansion of lactam‐tethered allenols to efficiently afford cyclic α‐ or β‐ketoamides with good yields and high chemo‐, regio‐, and diastereoselectivity, through controlled CC bondcleavage of the β‐ or γ‐lactamnucleus. Interestingly, in contrast to the rearrangement reactions of 2‐azetidinone‐tethered allenols, which lead to the corresponding tetramic acid derivatives (β‐keto lactam adducts) as the