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Comprehensive Summary: Different novel fused multicyclic iminosugars were synthesized from D‐ribose tosylate, aniline and vinyl ethyl ether by one‐pot three‐component stereoselective [4+2] reaction at different temperatures. The iminium‐ion is the key intermediate for the reaction. As a result, several complex fused iminosugars 3a were obtained by aza‐Diels‐Alder mechanism at 60 °C, while a series of aza‐C‐glycosides 5a were prepared by Mannich reaction at room temperature accompanied by another tetrahydroquinoline‐fused iminosugars 4a (tricyclic derivatives) through aza‐Diels‐Alder cycloaddition. This strategy will help to construct structurally diverse and bioactive iminosugar analogues. [ABSTRACT FROM AUTHOR]

A rapid and efficient one-pot synthesis of a series of four novel nuevamine aza-analogues is described based on the oxidative Ugi-type reaction and aza-Diels-Alder reaction as post-functionalization. A simple IBX-mediated oxidation of a secondary amine followed by isonitrile α-addition and finally an aza-Diels-Alder cycloaddition provides the desired compounds in excellent overall yields considering the short reaction time, atom economy, and the molecular complexity of the final products. This protocol presents a highly attractive procedure for the rapid generation of fused polyheterocycles. [ABSTRACT FROM AUTHOR]

Microwaves assisted azaDiels-Alder cycloaddition reactions using aromatic and heteroaromatic Schiff bases as heterodienes and 3,4-dihydro- 2H-pyrane (DHP) as dienophyle in the presence of iodine catalyst, afforded stable cycloaddition adducts, as well as their oxidation products. The structures of the new hexahydro-2H-pyrano[3,2-c]quinoline and 3-(3-hydroxypropyl)- quinoline derivatives were assigned based on spectroscopic methods (high resolution NMR and mass spectrometry). [ABSTRACT FROM AUTHOR]

Abstract: The aza-Diels–Alder reactions of two 2-aminophenols in combination with six substituted benzaldehydes and two electron-rich cyclic alkenes were investigated under controlled microwave heating. The reactions were carried out in the presence of a catalytic amount of CF3CO2H in MeCN at 60°C for 15min, affording highly functionalized 8-hydroxy-1,2,3,4-tetrahydroquinolines in 39–59% isolated yields and in 36:64–16:84 diastereomer ratios in favor of the trans isomers. The microwave-heated three-component aza-Diels–Alder reactions completed in significantly reduced reaction time to give the same level of chemical yield and diastereomer ratio obtained from the room temperature reaction. [Copyright &y& Elsevier]