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Cross-conjugated 1-azatrienes (3-1-azadendralenes) bearing a sulfonyl group on the nitrogen atom were converted to various polyhydroquinolines with multiple stereocentres via a ...diene-transmissive hetero-Diels–Alder (DA) reaction consisting of an inverse electron-demand aza-DA reaction with electron-rich dienophiles followed by a stereoselective DA reaction with electron-deficient dienophiles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A TEMPO promoted oxidative aza‐Diels‐Alder reaction of ketohydrazones with 3‐methyleneoxindoles or 2‐arylidene‐1,3‐indanediones were successfully developed, This reaction provided an efficient ...synthetic protocol for novel functionalized spiroindoline‐3,3′‐pyridazines and spiroindene‐2,3′‐pyridazines. This reaction showed high diastereoselectivity and strict substituent's electron effect, which might be due to the reaction mechanisms process including sequential oxidative generation of 1,2‐diaza‐1,3‐dien and normal electron‐demand aza‐Diels‐Alder reaction.
Spiroindoline‐3,3′‐pyridazine and spiroindene‐2,3′‐pyridazine were efficiently and diastereoselective synthesized from TEMPO‐promoted oxidative aza‐Diels‐Alder reaction of ketohydrazones.
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BFBNIB, FZAB, GIS, IJS, KILJ, OILJ, SBCE, SBMB, UPUK
beta-Vinyl-substituted chromenes were obtained from 1H-benzofchromene-2-carbaldehydes and 6-bromo-4H-chromene-3-carbaldehyde by the Wittig reaction. The Diels-Alder reaction of the ...beta-vinyl-substituted chromenes with dimethyl acetylenedicarboxylate, ninhydrin, and diethyl 2,3-dicyanofumarate yielded spiro-substituted 3,10a-dihydro-2H,5H-pyrano2,3-bchromenes, derivatives of 7a,10-dihydro-12H-benzoaxanthene and 7a,8,10,12-tetrahydro-9H-benzoaxanthene.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this contribution, we describe a new approach to apply thermodynamically unfavored reactions in synthetic chemistry and to integrate them in cascade processes. By means of a new developed ...procedure for multi‐step one‐pot syntheses, we succeeded in nearly completely converting a thermodynamically labile Diels–Alder adduct, which strongly tends to react back, to the target product with high conversion of >99 % and in excellent yield by coupling with a rapid subsequent hydrogenation reaction. In detail, the process is based on the use of a rotating reaction vessel to form a thin product film of the thermodynamically labile Diels–Alder product from 2‐methylfuran and maleic acid anhydride (as two bio‐based raw materials), which then slowly dissolves into solution and is immediately converted by hydrogenation to the target product. Such a combination of Diels–Alder reaction and hydrogenation in a sequential one‐pot process without by‐product formation enables the efficient production of the product, which represents a valuable bio‐based platform chemical. In addition, this process concept generally opens a perspective for the integration of thermodynamically unfavorable reaction steps in multi‐step one‐pot cascade processes while obtaining the desired target products in high yields.
A cascade process for synthesis and conversion of a thermodynamically labile Diels–Alder adduct proceeds with high conversion of >99 % by coupling of the Diels–Alder reaction with a rapid hydrogenation. A rotating reaction vessel leads to a thin film of the intermediate, which then slowly dissolves into an immediately convertible solution.
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BFBNIB, FZAB, GIS, IJS, KILJ, OILJ, SBCE, SBMB, UPUK
The reactions of 5-(1,2-dicarbadodecaboran-1-yl)-3-(2-pyridyl)-1,2,4-triazines with various dienophiles (2,5-norbornadiene, 1-morpholinocyclopentene, 1,2-dehydrobenzene, and 2-amino-4-phenyloxazole) ...were studied. It was shown that the presence of a carborane fragment in the 1,2,4-triazine ring causes an atypical reaction with dienophiles without the formation of the expected aza-Diels-Alder reaction products except for the reaction with 2,5-norbornadiene. The reaction of 5-(1,2-dicarbadodecaboran-1-yl)-3-(2-pyridyl)-1,2,4-triazines with 2-amino-4-phenyloxazole unexpectedly led to the formation of the corresponding 4,5-dihydro-1,2,4-triazines. One of the previously described procedures for the direct introduction of a carborane residue into the C.sup.5 position of 1,2,4-triazines was optimized.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A three-component condensation of alpha-naphthol, aromatic aldehydes, and beta-enaminones in acetic acid under reflux led to beta-carbonylsubstituted (with respect to the pyran oxygen atom) ...4-aryl-4H-benzohchromenes. The reaction is a cascade process involving the generation of 1,2-naphthoquinone-2-methide, the Diels-Alder reaction involving push-pull beta-enaminone, and the subsequent elimination of a secondary amine.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
No copper needed: In recent years, a large number of metal-free click reactions have been reported based on thiol-ene radical additions, Diels-Alder reactions, and Michael additions. In this ...Minireview, special attention is given to the advantages and limitations of the different methods to evaluate whether they have the potential to surpass the overwhelming success of the copper(I)-catalyzed azide-alkyne cycloaddition.The overwhelming success of click chemistry encouraged researchers to develop alternative "spring-loaded" chemical reactions for use in different fields of chemistry. Initially, the copper(I)-catalyzed azide-alkyne cycloaddition was the only click reaction. In recent years, metal-free 3+2 cycloaddition reactions, Diels-Alder reactions, and thiol-alkene radical addition reactions have come to the fore as click reactions because of their simple synthetic procedures and high yields. Furthermore, these metal-free reactions have wide applicability and are physiologically compatible. These and other alternative click reactions expand the opportunities for synthesizing small organic compounds as well as tailor-made macromolecules and bioconjugates. This Minireview discusses the success and applicability of new, in particular metal-free, click reactions.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
8.
Light-Induced Click Reactions Tasdelen, Mehmet Atilla; Yagci, Yusuf
Angewandte Chemie (International ed.),
June 3, 2013, Volume:
52, Issue:
23
Journal Article
Peer reviewed
Spatial and temporal control over chemical and biological processes, both in terms of “tuning” products and providing site‐specific control, is one of the most exciting and rapidly developing areas ...of modern science. For synthetic chemists, the challenge is to discover and develop selective and efficient reactions capable of generating useful molecules in a variety of matrices. In recent studies, light has been recognized as a valuable method for determining where, when, and to what extent a process is started or stopped. Accordingly, this Minireview will present the fundamental aspects of light‐induced click reactions, highlight the applications of these reactions to diverse fields of study, and discuss the potential for this methodology to be applied to the study of biomolecular systems.
Shine a light: Owing to their ease of implementation and the availability of inexpensive light sources, light‐induced click reactions (see picture) have become a powerful methodology for the synthesis of materials and the modification of biomaterials. Fundamental aspects of these reactions and their application in surface and materials science, as well as their potential in the study of biomolecular systems are highlighted.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
We describe a novel and intriguing strategy for the construction of efficient heterogeneous catalysts by hypercrosslinking catalyst molecules in a one‐pot Friedel–Crafts alkylation reaction. The new ...hypercrosslinked polymers (HCPs) as porous solid catalysts exhibit the combined advantages of homogeneous and heterogeneous catalysis, owing to their high surface area, good stability, and tailoring of catalytic centers on the frameworks. Indeed, a new class of metalloporphyrin‐based HCPs were successfully synthesized using modified iron(III) porphyrin complexes as building blocks, and the resulting networks were found to be excellent recyclable heterogeneous catalysts for the hetero‐Diels–Alder reaction of unactivated aldehydes with 1,3‐dienes. Moreover, this new strategy showed wide adaptability, and many kinds of homogeneous‐like solid‐based catalysts with high catalytic performance and excellent recyclability were also constructed.
Holey HCPs: Porous solid catalysts were constructed from hypercrosslinking polymers (HCPs), and exhibited the combined advantages of homogeneous and heterogeneous catalysis. New metalloporphyrin‐based polymers were found to be excellent recyclable heterogeneous catalysts for the hetero‐Diels–Alder reaction of unactivated aldehydes with 1,3‐dienes. This strategy demonstrated a wide applicability, and many kinds of homogeneous‐like solid catalysts were constructed.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Quantum chemical calculations are used to investigate the experimentally measured reactivities of cyclic dienes and cycloalkenones in the Diels–Alder reaction. The interaction energies (red) are ...nearly constant; differences arise in changes in distortion energies of both dienophile (blue) and diene (green; see picture, Ea=activation energy; values in kcal mol−1).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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