Palladium-catalyzed aza-Wacker cyclization of O-homoallyl benzimidates: expeditious access to heteroatom-rich substituted 1,3-oxazines via alkene trifunctionalization

Abstract

A palladium-catalyzed aza-Wacker cyclization of O-homoallyl benzimidates has been developed to afford a variety of useful 4-methylene-1,3-oxazine building blocks in moderate to good yields. The synthetic utility of the 4-methylene-1,3-oxazines...

Switchable Regioselective 7-endo or 6-exo Iodocyclization of O-Homoallyl Benzimidates

“…Substrates 1 − were prepared according to the literature. 1a – 1q , 1s , and 1u – 1w spectral data are consistent with those reported in the literature.…”

“…In 2021, our group developed methods for aminosulfonylation and aminoselenation of the same starting material to obtain sulfonylated and selenated 1,3-oxazines using copper catalysis . Very recently, we reported a palladium-catalyzed aza -Wacker cyclization of O -homoallyl benzimidates affording a variety of useful 4-methylene-1,3-oxazine building blocks . Although great progress has been achieved above, considering that, in most cases, the biological profile of 1,3-oxazine and 1,3-oxazepine frameworks relies on their substitution patterns and structural diversity; the research to further explore the selective synthesis of iodo-containing 1,3-oxazines and tetrahydro-1,3-oxazepines from O -homoallyl benzimidates via intramolecular electrophilic iodocyclization is still important (Scheme c).…”

Electrochemical Ring-Opening of Cyclopropylamides with Alcohols toward the Synthesis of 1,3-Oxazines

“…1,3-Oxazines are an important class of N , O -containing heterocycles found in natural products, bioactive agents, and versatile synthetic intermediates . Accordingly, several synthetic approaches have been developed for the synthesis of these motifs, including [4 + 2] cycloaddition, cyclization of imidates, and intramolecular aza- Wacker oxidation . Nevertheless, new synthetic approaches to access 1,3-oxazines are still desirable.…”