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...
An efficient aminofluorosulfonylation strategy was developed for the synthesis of various pyrazoline-functionalized aliphatic sulfonyl fluorides using β,γ-unsaturated hydrazones with sulfur dioxide and NFSI as the starting materials under mild conditions. The sulfonyl fluoride products could be successfully transformed into the corresponding sulfonate esters and amides via the sulfur(VI) fluoride exchange (SuFEx) click reactions. Preliminary mechanistic investigations demonstrate that the reaction operates through a radical cyclization/SO 2 insertion/fluorination cascade process.
We present a facile switchable regioselective 7-endo or 6-exo iodocyclization of O-homoallyl
benzimidates here, which affords various iodo-substituted 1,3-oxazines
and tetrahydro-1,3-oxazepines in a controllable manner. The products
can further undergo substitution reactions to afford a series of rich
functionalized target heterocyclic molecules. The developed protocol
has the advantages of mild conditions, simple operation, and excellent
functional group compatibility.
Amines, especially those with multi-nitrogen moieties,
are widespread
in natural products and biologically active compounds. Thus, the development
of direct and efficient methods to introduce multiple nitrogen-containing
fragments into compounds in one step is highly desirable yet challenging.
Herein, we report an NIS-promoted selective amino-diazidation and
amino-iodoazidation of O-homoallyl benzimidates with
NaN3. By using this protocol, a variety of vicinal diazido-substituted
1,3-oxazines and vicinal iodoazido-substituted 1,3-oxazines were directly
synthesized in a controllable manner. Preliminary mechanistic investigations
revealed that the reaction operates through a NIS-promoted four-step
cascade process. The developed method has the merits of metal-free,
excellent functional group compatibility, simple operation, and mild
conditions.
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