Inter- and Intramolecular Hetero-Diels-Alder Reactions; Part 50: Domino Reactions in Organic Chemistry: The Knoevenagel-hetero-Diels-Alder-Hydrogenation Sequence for the Biomimetic Synthesis of Indole Alkaloids via Strictosidine Analogues

Tandem [4+2]/[3+2] Cycloadditions of Nitroalkenes

“…The classic examples of tandem cascade cycloadditions are the “pincer” (path a) and “domino” (path b) mode of Diels−Alder reactions which have served as cornerstones in the syntheses of the formidable pagodane and dodecahedrane structures, respectively (Scheme ). Despite the obvious potential of this process and the myriad of conceivable permutations, only a handful of tandem cascade cycloadditions have been developed, most notably the intermolecular [3+2]/intramolecular [4+2] and double intermolecular [4+2] variety due to Tsuge 1 …”

Solid-State Melt Reaction for the Domino Process: Highly Efficient Synthesis of Fused Tetracyclic Chromenopyran Pyrimidinediones Using Baylis−Hillman Derivatives

“…Recently, domino reactions have become very attractive and a useful strategy which minimizes the reaction steps to achieve the target complex organic compounds with high yields. The domino Knoevenagel intramolecular hetero-Diels−Alder reaction is one of the most powerful synthetic routes for the synthesis of various heterocycles and natural products. ,, The domino Knoevenagel intramolecular hetero-Diels−Alder reaction has also been extensively employed for the synthesis of polycyclic compounds, especially for the synthesis of chromenopyran pyrimidinedione ring systems. ,,,, …”

Intra- and Intermolecular 1,3-Dipolar Cycloaddition of Sugar Ketonitrones with Mono-, Di-, and Trisubstituted Dipolarophiles

“…In particular, we selected 3-methyl-but-2-en-1-ol ( 22 ). We also chose trisubstituted enol ether (2-methyl-propenyloxymethyl)benzene ( 23 ), first because on reaction with a C5-sugarketonitrone it would render a quaternary center with the substitution (+)-lactacystin requires at that center and also because its electron-rich character would probably favor its reaction with the electron-poor ketonitrone 5h . However, either no reaction was observed, e.g., refluxing in toluene, or a complex mixture was obtained when the conditions were forced (heating at 160 °C in a sealed tube).…”