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Prolina : pospolity aminokwas wyjątkowy katalizator. Część IV, Reakcja Michaela

Karczmarska-Wódzka A., Studzińska R., Kołodziejska R., Wróblewski M., Dramiński M.

Wiadomości Chemiczne

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2014

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[Z] 68, 1-2

49--65

EN

In recent years there has been a dynamic development of asymmetric synthesis. Groups of researchers, particularly the one led by Benjamin List and Carlos Barbas, carried out a number of reactions and showed the effectiveness of the use of small organic molecules such as proline as catalysts. Michael addition catalyzed with proline is a particularly interesting reaction because it can be carried out in two aminocatalytic pathways. The analysis of Michael reaction reveals potential for both forms of aminocatalysis: enamine and iminium catalysis (Scheme 1) [1–14]. Presumably Michael reaction proceeds mainly according to enamine mechanism. The use of proline in Michael reaction with imine activated acceptor is slightly effective. So far the researches have shown that the modification of proline molecule or addition of other catalyst is necessary for condensation to appear. Enamine catalysis concerns the activation of carbonyl compound in situ being a donor. There is no need for enolase anion to be created earlier [2, 15–17]. When, as a result of the reaction of a,b-unsaturated carbonyl compound with proline, Michael acceptor activation appears it means that it is enamine mechanism reaction (Scheme 1) [2, 24]. One of the first examples of direct Michael reaction proceeding through enamine transition state is the reaction of cyclopentanone with nitrostyrene (Scheme 6) [20–23]. Other examples of Michael addition of ketone with nitro olefin catalysed by proline are shown in table 2 and 3 [10, 23, 30]. Nitroketones obtained in that way are useful as precursors for different organic compounds [33], also pyrrolidines [34]. Pyrrolidines are pharmacologically active and they selectively block presynaptic dopamine receptors [34] (Scheme 7). Except for Michael intermolecular reaction, intramolecular condensation adducts were also obtained. Michael intramolecular proline-catalyzed condensation in which inactive ketones transform into α,β-unsaturated carbonyl compounds was described (Scheme 9) [35, 36]. These reactions require a stoichiometric amount of a catalyst and a long time of reaction and they give as a result a little enantiomeric excess [11, 24, 35]. In 1991, Yamaguchi and co-workers carried out malonates Michael addition to α, β-unsaturated aldehydes catalyzed by L-proline [24, 39]. The reaction proceeded according to enamine mechanism, for example dimethyl malonate was reacted with hex- 2-enal in the presence of proline to give Michael adduct in 44% yield. To improve the yield an attempt of a slight modification of a proline molecule was made transforming it into proper salt. Proline lithium salt enabled to obtain the condensation product in 93% yield (Tab. 4). Regardless of a used catalyst the products in the form of racemates were obtained. In order to improve enantioselective properties of a catalyst, Michael addition of diisopropyl malonate to cycloheptenone was carried out in chloroform in the presence of different proline salts. Optimal enantioselectivity and yield was obtained by using rubidium salt (Tab. 5–7) [40, 41]. Rubidium prolinate-catalyzed Michael additions are used in industry e.g. for enantioselective synthesis of the selective serotonine reuptake inhibitior (SSRI) (–)-paroxetine (antidepressant) (Scheme 12) [24].

2

Otrzymywanie hydrofobowych półproduktów do syntezy diesterquatów z wykorzystaniem wielofunkcyjnego reaktora LabMax

Zieliński W., Skrzela R., Lamch Ł., Wilk K. A.

Przemysł Chemiczny

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2012

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T. 91, nr 4

499-505

PL

Przedstawiono wyniki badań wpływu parametrów, takich jak temperatura i szybkość dozowania substratu, na przebieg reakcji addycji Michaela w wielkolaboratoryjnych badaniach procesu addycji metyloaminy do akrylanów alkilowych. Dokonano optymalizacji warunków reakcji Michaela decydującej o kinetyce procesu. Zastosowanie odpowiedniej temperatury początkowej i szybkości dozowania roztworu metyloaminy pozwoliło na zwiększenie wydajności procesu (w stosunku do wcześniej stosowanych warunków) i praktyczne wyeliminowanie tworzenia się produktów ubocznych.

EN

Three CH₂=CHCOOR (R = Me, C₆H₁₃, C₁₂H₂₅) were converted with MeNH₂ at 10–20°C in alc. soln. (2 L reactor) to resp. MeN(CH₂CH₂COOR)₂ diesterquats. The reaction course was followed by IR spectroscopy to det. the optimum rate of MeNH₂ dosing. The reaction yield decreased with increasing the dosing rate and the R chain length. The initial temp. did not show any substantial effect on the reaction course.

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Chiralne katalizatory organiczne w asymetrycznej reakcji Michaela

Albrecht Ł., Krawczyk H.

Wiadomości Chemiczne

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2009

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[Z] 63, 5-6

391-436

EN

In marked contrast to enantioselective Michael reactions promoted by chiral Lewis acids, organocatalytic Michael reactions have not been used as standard transformation in organic chemistry until quite recently. During the past few years chiral organocatalysts have emerged as a broadly applicable class of catalysts for enantioselective Michael reaction. This review summarizes these advances emphasizing the structural and mechanistic features that contribute to high enantioselectivity in organocatalytic Michael reactions. The first part of this review deals with the development of covalent catalysis in organocatalytic asymmetric Michael reactions. To date, several chiral secondary amines have been employed to promote formation of electron-rich enamines from enolizable aldehydes and ketones, which then react with various ?,?-unsaturated electrophiles to afford products [7-24]. In contrast, chiral imidazolidinones and diarylprolinol ethers are most often used to activate ?,?-unsaturated carbonyl compounds by forming electron-deficient iminium ions, which render the ?-carbon more electrophilic then their carbonyl precursors for nucleophilic attack [2a, 7, 25-34]. The second part of this review documents the development of non-covalent catalysis [35-64]. In this regard, chiral Bronstedt bases [35-39], chiral phase-transfer catalysts [40-49] and chiral hydrogen-bond donors [50-64] have emerged in the past few years as readily accessible organocatalysts of asymmetric Michael reaction. The most efficient catalysts such as cinchona alkaloids and their derivatives, quaternary ammonium salts obtained from cinchona alkaloids and chiral thiourea derivatives, respectively are revived and the modes of actions are discussed. Furthermore, the major developments of organocatalytic asymmetric Michael reactions are also reviewed.

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Phase Transfer Catalyzed Reactions of Chloroform with Methacrylic Esters

Fedoryński M., Błażejczyk A., Mąkosza M.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 5

709-717

EN

Chloroform reacts with an excess of methyl methacrylate in the presence of 50% aq NaOH and benzyltriethylammonium chloride (TEBA) as a catalyst (phase transfer catalysis, PTC) to give a mixture of dichlorocarbene and trichloromethyl anion adducts, 1 and 2, respectively. These additions proceed as parallel processes, there is a slow conversion of 2_ 1, which proceeds as an intramolecular process.

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Kwasy alkanowe i akrylowe z grupą elektronoakceptorową przy atomie C-2. Nowe zastosowanie syntetyczne

Krawczyk H.

Zeszyty Naukowe. Rozprawy Naukowe / Politechnika Łódzka

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2000

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Z. 280

3-73

PL

Zbadano reakcję Mannicha kwasu dietylofosfonooctowego 2 oraz kwasu cyjanooctowego 4 z formaldehydem i drugorzędowymi aminami i wykazano możliwość sterowania jej selektywnością. Opracowano warunki transformacji kwasu dietylofosfonooctowego 2 odpowiednio w aminometylowinylofosfoniany 7a-g, alkoksy-metylowinylofosfoniany 11a-e, 2-dietylofosfonoakrylan dicykloheksylo-amoniowy 47 oraz winylofosfonian dietylu 26. Kwas cyjanooctowy przekształcono w aminometyloakrylonitryle 8a-b i 2-cyjanoakrylan dicykloheksyloamoniowy 48. Zaproponowano również syntezę 1-podstawionych winylofosfonianów 12a-f, wykorzystując pochodne kwasu dietylofosfonooctowego o strukturze 3a-f jako materiały wyjściowe. Odkryto, że reakcja Michaela akrylanów dicykloheksyloamonio-wych 47, 48 z wybranymi CH pronukleofilami, NH pronukleofilami oraz fenolami przebiega w warunkach samokatalizy. Opracowano syntezę 2-dietylofosfonoalkanianów 54a-e i 57a-c opartą na addycji związków 1,3-dikarbonylowych i monokarbonylowych do akryłanu 47. Analogiczna reakcja 2-cyjanoakrylanu 48 ze związkami 1,3-dikarbonylowymi umożliwiła syntezę 2-cyjanoalkanianów 60a-e. Addycja NH pronukleofili do akrylanów 47 i 48 dała 2-dietylofosfono-propioniany 63a-e i 2-cyjanopropioniany 64a-e. Badając zakres stosowalności hydroksyarenów jako pronukleofili ustalono, że fenol 67a i jego monopodstawione pochodne 67b-e w reakcji z fosfonoakrylanem 47 dają prawie wyłącznie produkty O-addycji 69a-e. 2-Naftol,1-naftol, dihydroksynaftaleny, fenantrol oraz polihydro-ksyfenole przekształcane są natomiast w C-addukty Michaela 79, 88, 83, 84, 89, 85, 92, 93, 96, 97. W analogicznej reakcji 2-cyjanoakrylan 48 dał 3-arylo-2-cyjanopropioniany 99-103. Zaproponowano wyjaśnienie obserwowanych faktów doświadczalnych.

EN

The Mannich reaction of diethylphosphonoacetic acid 2 and cyanoacetic acid 4 with formaldehyde and secondary amines has been studied and methods for controlling its selectvity have been developed. Aminomethylvinylphosphonates 7a-g, alkoxymethylvinyl-phosphonates 11a-e, dicyclohexylammonium 2-diethylphosphonoacrylate 47 and diethyl vinylphosphonate 26 were prepared starting from diethylphosphonoacetic acid 2. Cyanoacetic acid 4 was transformed into aminomethylacrylonitriles 8a-b and dicyclohexylamonium 2-cyano-acrylate 48. Diethylphosphonoalcanoic acids 3a-f were coverted into 1-substituted vinylphosphonates 12a-e. It was discovered that Michael reaction of dicyclohexylammonium acrylates 47 and 48 with CH pronucleophiles, NH pronucleophiles and phenols proceeds under self-catalytic conditions. The synthesis of 2-diethylphosphonoalkanoates 54a-e and 57a-e, based on the addition of 1,3-dicarbonyl and monocarbonyl compounds to acrylate 47 was developed. The analogous reaction of 2-cyanoacrylate 48 with 1,3-dicarbonyl compounds resulted in the formation of 2-cyanoalkanoates 60a-e. Addition of NH pronucleophiles to acrylates 47 and 48 produced 2-diethylphosphonopropanoates 63a-e and 2-cyanopropanoates 64a-e. Phenol 67a and its monosubstituted derivatives reacted with acrylate 47 to give almost exclusively O-adducts 67a-e. In contrast 2-naphthol, 1-naphthol, dihydroxynaphthalenes, phenanthrol and polyhydroxy phenols could be converted into C adducts 79, 88, 83, 84, 89, 85, 92, 93, 96, 97. The analogous reaction of 2-cyanoacrylate 48 gave 3-aryl-2-cyanopropanoates 99-103. Mechanistic explanation of experimental results has been proposed.