oxadiazepines via 1,5-hydride shift/cyclization of pyrrolidine- or tetrahydroisoquinoline-containing nitrones has been developed. With 1,3-dipole nitrones serving as the hydride acceptors, this transformation was promoted by a Lewis acid, providing access to structurally diverse oxadiazepines in good yields. A one-pot process for in situ nitrone formation, a 1,5-hydride shift, and ring cyclization was also
Catalyst-free construction of spiro [benzoquinolizidine-chromanones] <i>via</i> a tandem condensation/1,5-hydride transfer/cyclization process
作者:Siyuan Liu、Hang Wang、Baomin Wang
DOI:10.1039/d0ob01887b
日期:——
A highly efficient and quite mild protocol to achieve spiro [benzoquinoline-chromanones] through a catalyst-free condensation/[1,5]-hydride shift/6-endo cyclization sequence was developed.
Diastereoselective Spirocyclization via Intramolecular C(
<i>sp</i>
<sup>3</sup>
)−H Bond Functionalization Triggered by Sequential [1,5]‐Hydride Shift/Cyclization Process: Approach to Spiro‐tetrahydroquinolines
作者:Arup Bhowmik、Sumit Das、Writhabrata Sarkar、K. M. Saidalavi、Aniket Mishra、Anupama Roy、Indubhusan Deb
DOI:10.1002/adsc.202001011
日期:2021.2.2
functionalization triggered by sequential [1,5]‐ hydrideshift /cyclization sequence using ortho amino benzaldehydes and active methylene compounds such as 2‐coumaranone, 4‐hydroxycoumarin, 3‐coumaranone, and 3‐isochromanone. This protocol provides a Lewis acid catalyst‐free straight forward one‐pot reaction in cases of 2‐coumaranone and 4‐hydroxycoumarin, Lewis acid‐catalyzed stepwise reaction for 3‐coumaranone
The first example of a catalytic enantioselective intramolecular hydride shift/ring closure reaction is reported. This redox neutral reaction cascade allows for the efficient formation of ring-fused tetrahydroquinolines in high enantioselectivities.
An N‐heterocyclic carbene catalyzed photooxidation reaction via intramolecular cross dehydrogenative coupling of tetrahydroisoquinoline‐tethered aldehydes was developed, giving the corresponding oxidative cyclization products in moderate to good yields. This reaction features mild conditions with oxygen as the terminal oxidant in the absence of photocatalyst.