Titanium Tetrachloride‐Mediated Approach to Access 2‐Chloro‐2‐Substituted Isoindolin‐1‐ones through the Addition of Alkynes to Acyliminium ions

Abstract

An asymmetric approach to access 2‐substituted isoindolin‐1‐ones 9–11 was developed through TiCl4‐mediated addition‐chlorination of N,O‐acetals 7 a–7 c with terminal alkynes 8. A range of substrates were amenable to this transformation, and the desired substituted isoindolin‐1‐ones were obtained in moderate to good yields with moderate diastereoselectivities.

AgNTf2 catalyzed cycloaddition of N-acyliminium ions with alkynes for the synthesis of the 3,4-dihydro-1,3-oxazin-2-one skeleton

“…21 It is worth noting that TiCl 4 could mediate the addition of cyclic N , O -acetals with terminal alkynes to give addition–chlorination products. 22 To the best of our knowledge, the intermolecular cycloaddition of chain N , O -acetals with unsaturated carbon–carbon bonds is quite rare, with one example for alkynes (SnCl 4 mediated 14 ) and another example for olefins (anodic oxidation 15 ). Herein, we present our AgNTf 2 -catalyzed [4 + 2] cycloaddition of chain N , O -acetals with terminal alkynes, providing an efficient synthetic approach to 4,6-substituted 3,4-dihydro-1,3-oxazin-2-ones.…”