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Intramolecular reaction
About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.
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TL;DR: In work directed toward a total synthesis of chartelline A, a strategy was investigated to construct the 10-membered ring of this marine alkaloid via an intramolecular aldehyde/beta-lactam cyclocondensation to form the macrocyclic enamide functionality through a Staudinger ketene-imine [2 + 2]-cycloaddition strategy.
Abstract: In work directed toward a total synthesis of chartelline A (1a), a strategy was investigated to construct the 10-membered ring of this marine alkaloid via an intramolecular aldehyde/β-lactam cyclocondensation to form the macrocyclic enamide functionality. Therefore, spiro-β-lactam and imidazole fragments were first prepared. Tribromooxindole β-lactam 24 was synthesized from commercially available 5-nitroisatin (18) in seven steps and 30% overall yield via a Staudinger ketene−imine [2 + 2]-cycloaddition strategy. The requisite 2-bromoimidazole subunit 40 bearing a terminal alkyne and a masked aldehyde was efficiently prepared from the readily available imidazole ester 25 in 10 steps. With both advanced intermediates available, the addition of the lithium acetylide generated from 2-bromoimidazole subunit 40 to the γ-lactam carbonyl group of N-Boc-tribromooxindole 24 was investigated, affording the desired N-Boc-aminal 41. Hydrolysis of the acetonide moiety of 41, followed by oxidative cleavage of the result...
77 citations
77 citations
TL;DR: The Fe(ClO(4))(3)-catalyzed intramolecular rearrangement/cyclization/oxidation reaction sequence for the synthesis of alpha-carbonyl furan derivatives from electron-deficient alkynes and 2-yn-1-ols is reported.
Abstract: The Fe(ClO4)3-catalyzed intramolecular rearrangement/cyclization/oxidation reaction sequence for the synthesis of α-carbonyl furan derivatives from electron-deficient alkynes and 2-yn-1-ols is reported.
77 citations
77 citations
TL;DR: Catalytic asymmetric synthesis of neolignan natural products (-)-epi-conocarpan and (+)-conOCarpan has been achieved by exploiting an enantio- and diastereoselective intramolecular C-H insertion reaction to construct a cis-2-aryl-2,3-dihydrobenzofuran ring system as a key step.
Abstract: Catalytic asymmetric synthesis of neolignan natural products (−)-epi-conocarpan and (+)-conocarpan has been achieved by exploiting an enantio- and diastereoselective intramolecular C−H insertion reaction to construct a cis-2-aryl-2,3-dihydrobenzofuran ring system as a key step. The C−H insertion reaction of 5-bromoaryldiazoacetate catalyzed by Rh2(S-PTTEA)4, a new dirhodium(II) carboxylate complex that incorporates N-phthaloyl-(S)-triethylalaninate as chiral bridging ligands, provided 2-aryl-5-bromo-3-methoxycarbonyl-2,3-dihydrobenzofuran with exceptionally high diastereoselectivity (cis/trans = 97:3) and high enantioselectivity for the cis isomer (84% ee).
77 citations