Polysubstituted 2,3-dihydrofuro[2,3-b]pyridines and 3,4-dihydro-2H-pyrano[2,3-b]pyridines via microwave-activated inverse electron demand Diels–Alder reactions

Synthesis of 3‐Amino‐8‐azachromans and 3‐Amino‐7‐azabenzofurans via Inverse Electron Demand Diels–Alder Reaction

“…This molecular target is closely connected to the already proven stability and reactivity of 5-substituted triazines. [15] Thus, the intermediate II could be obtained by the substitution of a leaving group (in this case methylsulfonyl) incorporated in the triazine III with the alkynol IV (Scheme 1).…”

“…Softer reaction conditions for the five-membered cycloaddition derivatives were in agreement with published data. [15] Subsequent carbamate hydrogenolysis [30] afforded the free amines, which were used for the next step without further purification. The final reductive amination step, conducted Scheme 6.…”

“…Thus, for the synthesis of meta-substituted derivatives, the same synthetic approach described above was envisaged. After the synthesis of the particularly unstable 3-(methylsulfonyl)-1,2,4-triazine following the protocols described in the literature, [9,15] the next substitution step was performed under the same conditions as for the 5-substituted triazine (see Scheme 5). This reaction did not provide the desired compound, but only the oxazolidinone side product.…”

“…There are a few examples of halogen and hydroxy substitution from the studies of Choi et al [11] and Shiotani et al [12][13][14] A more recent article published by our group explored the synthesis of 3-or 4-hydroxy derivatives. [15] Using a more convergent strategy, we designed the synthesis of 3-aminoazachromans C (Figure 1) as potential 5-HT 7 ligands.…”

Microwave-Assisted Syntheses in Organic Chemistry

“…(95) featuring close structural similarity to bioactive molecules were obtained by the intramolecular hetero Diels-Alder cycloaddition of alkyne triazines (94) under MW conditions in good yields (Scheme 2.67) [104]. MW activation proved to be efficient to promote the cycloaddition reaction.…”