Silver(I)- and Base-Mediated [3 + 3]-Cycloaddition of C,N-Cyclic Azomethine Imines with Aza-oxyallyl Cations

Abstract

A silver(I) and base-mediated [3 + 3]-cycloaddition reaction of in situ generated C,N-cyclic azomethine imines with in situ formed aza-oxyallyl cations is reported. This one-pot cycloaddition process shows broad substrate scope an excellent functional group tolerance and provides the corresponding biologically important isoquinoline-fused triazines in good to excellent yields.

Transition‐Metal Free Construction of Isoquinoline‐fused Triazines Containing Alkenyl C−X Bonds

“…Thus, great research interests have been devoted to their facile synthesis in the past several years. However, to the best of our knowledge, only very limited methods have been developed for the construction of isoquinoline‐fused triazine derivatives, which are all based on the transition‐metal catalyzed cyclization or cycloaddition process, including rhodium, copper, and silver . Therefore, further development of highly efficient strategies for the preparation of these important fused heterocyclic ring structures under transition‐metal free conditions is of great significance.…”

“…Note that, organic base was not suitable for this transformation. Only trace amount or low yield of the desire product 3 aa was observed when DABCO, Et 3 N and DBU were involved ( Table 1, entries [11][12][13]. Finally, an increase in a-halohydroxamate concentration (2.0 equivalents) further improved the yield of product 3 aa to 96% ( Table 1, entry 14).…”

Comprehensive Strategies for the Synthesis of Isoquinolines: Progress Since 2008

“…These important isoquinoline‐fused triazines were obtained in good to excellent yields (Scheme 12). [51] …”

The Fascinating Chemistry of α‐Haloamides

“…Namely, nitrile imines gave 1,3,4‐oxadiazines, azides gave tetrazines, azomethine imines gave isoquinoline‐fused triazines, and nitrones provided 1,2,4‐oxadiazinan‐5‐ones –…”