Direct Amine-Catalyzed Enantioselective Synthesis of Pentacyclic Dibenzo[<i>b</i>,<i>f</i>][1,4]oxazepine/Thiazepine-Fused Isoquinuclidines along with DFT Calculations
A direct protocol for the asymmetric synthesis of dibenzoxazepine/thiazepine-fused [2.2.2] isoquinuclidines is developed. The reaction proceeds through a proline-catalyzed direct Mannich reaction followed by an intramolecular aza-Michael cascade sequence between 2-cyclohexene-1-one and various tricyclic imines, like dibenzoxazepines/thiazepines, as an overall [4 + 2] aza-Diels–Alder reaction. A series
catalytic asymmetric synthesis of new dibenzo[b,f][1,4]-oxazepine-fused 1,2-dihydropyridines (DHPs) has been described under metal-free conditions. This reaction proceeds through proline-catalyzed direct Mannich/cyclization between seven-membered dibenzo[b,f][1,4]-oxazepine-imines and aqueous glutaraldehyde, followed by IBX-mediated site-selective dehydrogenative oxidation in one-pot operation with high
Efficient Construction of Tetracyclic 1,2,4‐Triazoline‐Fused Dibenzo[
<i>b,f</i>
][1,4]oxazepines through KI/TBHP‐Mediated [3+2] Annulation between DBO‐Imines and
<i>N</i>
‐Tosylhydrazones
straightforward protocol for 1,2,4-triazoline-fused dibenzo[b,f][1,4]oxazepines is effectively established throughKI/TBHP-promoted [3+2] annulationbetweendibenzo[b,f][1,4]oxazepine-imines and N-tosylhydrazones under mild conditions. The produced 1,2,4-triazoline-fused DBOs could be easily converted into biologically interesting 1,2,4-triazolo-fused DBOs with excellent yields