A novel nitroaldol reaction catalyzed by rhodium complex in the presence of a silyl ketene acetal

Kiyooka, Syun‐ichi; Tsutsui, T.; Maeda, Hirofumi; Kaneko, Yuichi; Isobe, Kiyoshi

doi:10.1016/0040-4039(95)01314-8

Cited by 40 publications

(18 citation statements)

References 12 publications

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“…Since the Henry reaction creates stereogenic centers in the products, considerable effort has also been directed toward the development of enantioselective versions. 9,10 A lot of various new catalysts have recently been developed, like Amberlyst A-21, 11 benzyltrimethylammonium hydroxide, 12 rhodium complex, 13 proazaphosphatranes, 14 Mg-Al-O-tBu hydrotalcite, 15 heterobimetallic complexes with lanthanide BINOL system, 16 or guanidines. 17 Nevertheless, the development of new catalyst and procedure of the Henry reaction has been constantly in focus, because of the need to reduce the amount of toxic waste materials and byproducts, to develop new asymmetric catalyst, and to use less toxic, 'green' promoters.…”

Section: Introductionmentioning

confidence: 99%

Nitroaldol-reaction of aldehydes in the presence of non-activated Mg:Al 2:1 hydrotalcite; a possible new mechanism for the formation of 2-aryl-1,3-dinitropropanes

et al. 2005

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Section: Introductionmentioning

confidence: 99%

Nitroaldol-reaction of aldehydes in the presence of non-activated Mg:Al 2:1 hydrotalcite; a possible new mechanism for the formation of 2-aryl-1,3-dinitropropanes

et al. 2005

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“…vacuum to give the product; yield: 91 mg (88%); 1 The 1 H NMR spectrum of 10 compared favorably with that of an authentic sample. The 1 H NMR spectra of 12, [20] 14, [21] 16, [22] 18 [23] and 20 [23] compared favorably with those reported in the cited references.…”

Section: Azidophosphine Dendrimer (8b)mentioning

confidence: 71%

First Synthesis of a Highly Basic Dendrimer and its Catalytic Application in Organic Methodology

et al. 2004

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Sixteen OCH 2 CH 2 N 3 P(i-BuNCH 2 CH 2 ) 3 N substituents (A) containing the highly basic bicyclic azido-phosphine moiety shown, have been incorporated into the dendrimer [CH 2 Keywords: catalyst; dendrimers; organic catalysis; phosphine imine; proazaphosphatrane Dendrimer synthesis has fascinated chemists for more than a decade.[1] Phosphorus-containing dendrimers make up an active subarea [2] which have materials, biological and catalysis applications.[3] To our knowledge, however, no reports of catalytic reactions promoted by phosphorus-containing dendrimers have appeared in which the phosphorus-containing moiety itself functions as the active site. We disclose here the first such example and show that it is an efficient catalyst for useful organic transformations such as Michael addition, aldol condensation and isocyanate trimerization. Acyclic phosphine imines [RN ¼ P(NR 2 ) 3 ] constitute a class of strong nonionic bases [4] wherein C 6 H 5 N ¼ P(NMe 2 ) 3 , for example, displays a pK a of 20.9 in acetonitrile.[5] Such phosphorus imines have been found to be very useful in amino acid synthesis. [6,7] We have found that bicyclic 1a is a powerful catalyst for acylation, [8] Michael addition [9] and isocyanate trimerization.[10] We were thus attracted to the possibility of grafting such a bicyclic base to a dendrimeric framework. The synthetic approach we report here is based upon a previous study [11] in which we found that 1a is stable in the azide form [11a] whereas the analogous reaction with phenyl azide gives the iminophosphorane 1b.[11b]The strategy we chose for assembling the dendrimeric framework is shown in Scheme 1. In order to realize a substantial number of basic sites in the molecule, we decided to employ the diazido acid 6 to effect branching. Methyl 3,5-dihydroxybenzoate 3 on treatment with dibromoethane in the presence of 18-crown-6 and K 2 CO 3 gave the dibromoester 4 in 87% yield.Although a few procedures have been reported [12] for the conversion of a meta-dihydroxybenzene (namely, 1-benzyloxy-3,5-dihydroxybenzene) to the corresponding 3,5-bis(2-bromoethyloxy) derivative, none of them afforded the 3,5-bis(2-bromoethyloxy) derivative 4 as a clean product. We therefore developed a modified procedure in which dibromoethane is used as the solvent in the presence of finely powdered K 2 CO 3 to give 4, which was pure by 1 H and 13 C NMR spectroscopy. Conversion of 4 to 5 in 93% yield, followed by saponification and acidification gave diazido acid 6 in 90% yield, which was then condensed with DAB-Am-8 dendrimer to afford 7 in 35% yield. The hexadeca-azido dendrimer 7 was found to be pure by NMR spectroscopy, although its polydispersity value (M w /M n ¼ 1.159 versus a polystyrene standard) obtained by GPC analysis was not ideal (1.00), presumably due to aggregation that occurred in the carrier solvent (THF).[13] Molecular weights estimated by GPC relative to a polystyrene standard depend on the shape and flexibility of the molecules and were considerably lower than calculated values,...

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“…5 Recently several improved procedures have been developed which include the use of alumina surface, 6 Amberlyst A-21, 7 potassium exchanged layered zirconium phosphate, 4e rhodium complex, 8 NaOH-catalyzed process in the presence of cetyltrimethylammonium chloride (CTACl), 9 tetramethylguanidine, 10 dendritic catalysts, 11 SiO 2 /microwave, 12 Mg-Al hydrotalcite, 13 and proaza-phosphatranes. 4 To achieve better yields of 2-nitroalkanol a careful control of the basicity of the reaction medium is crucial, so long reaction times are demanded.…”

Section: Methodsmentioning

confidence: 99%

Facile Synthesis of 2-Nitroalkanols Mediated with LiAlH₄as Catalyst

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A novel nitroaldol reaction catalyzed by rhodium complex in the presence of a silyl ketene acetal

Cited by 40 publications

References 12 publications

Nitroaldol-reaction of aldehydes in the presence of non-activated Mg:Al 2:1 hydrotalcite; a possible new mechanism for the formation of 2-aryl-1,3-dinitropropanes

Nitroaldol-reaction of aldehydes in the presence of non-activated Mg:Al 2:1 hydrotalcite; a possible new mechanism for the formation of 2-aryl-1,3-dinitropropanes

First Synthesis of a Highly Basic Dendrimer and its Catalytic Application in Organic Methodology

Facile Synthesis of 2-Nitroalkanols Mediated with LiAlH₄as Catalyst

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A novel nitroaldol reaction catalyzed by rhodium complex in the presence of a silyl ketene acetal

Cited by 40 publications

References 12 publications

Nitroaldol-reaction of aldehydes in the presence of non-activated Mg:Al 2:1 hydrotalcite; a possible new mechanism for the formation of 2-aryl-1,3-dinitropropanes

Nitroaldol-reaction of aldehydes in the presence of non-activated Mg:Al 2:1 hydrotalcite; a possible new mechanism for the formation of 2-aryl-1,3-dinitropropanes

First Synthesis of a Highly Basic Dendrimer and its Catalytic Application in Organic Methodology

Facile Synthesis of 2-Nitroalkanols Mediated with LiAlH4as Catalyst

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Facile Synthesis of 2-Nitroalkanols Mediated with LiAlH₄as Catalyst