AbstractThe coupling-isomerization reaction (CIR) of electron-deficient halides 1 with N-[1-(hetero)arylprop-2-ynyl] tosyl amides 2 leads to the formation of N-tosyl enimines 3, in good to excellent yields. These electron deficient heterodienes are perfectly suited for Diels-Alder reactions with inverse electron demand. In the sense of a one-pot reaction a three-component CIR-cyclocondensation sequence of 1, 2a, and diethyl ketene acetal gives rise to the formation of 2-ethoxy 6-(p-anisyl)pyridines 4 in moderate to good yields.
We report an air-stable bisboron complex as an efficient catalyst for the inverse electron-demand Diels–Alder (IEDDA) reaction of 1,2-diazine as well as 1,2,4,5-tetrazine. Its stability towards air and moisture was demonstrated by NMR studies enabling its application in organic transformations without glovebox. A one-pot procedure for its synthesis was developed starting from 1,2-bis(trimethylsilyl)benzene greatly enhancing its practicality. Comparative reactions were carried out to evaluate its catalytic activity in IEDDA reactions of diazine including phthalazine as well as 1,2,4,5-tetrazine.
An inverse-electron-demand [4+2] cycloaddition of in situ generated aliphatic vinyl ethers and electron-deficient ortho-quinone methides (o-QMs) has been developed. The reaction of in situ generated aliphatic vinyl ethers with o-QMs afforded the corresponding 3-alkylchromanes with high stereo- and regioselectivities. The method provides a versatile access to functionalized 3-alkylchromanes and it constitutes a useful tool for the synthesis of biologically active chromanes.
Sn-PILC: A novel efficient and recyclable catalyst for one-pot three component Povarov’s inverse-electron-demand hetero Diels-Alder reaction for a facile synthesis of tetrahydropyranoquinoline derivatives under neat conditions.