Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• enantioselectivity. In a relatively successful example, the chiral aminophosphine G9 catalyzed the asymmetric double-Michael reaction between o-tosylamidophenyl malonate and 3-butyn-2-one to give the indoline derivative in 69% yield and up to 10% ee (Scheme 53). 2.15 Annulation through tandem Michael addition/Wittig

A new charge-tagged proline-based organocatalyst for mechanistic studies using electrospray mass spectrometry

• J. Alexander Willms,
• Rita Beel,
• Martin L. Schmidt,
• Christian Mundt and
• Marianne Engeser

Beilstein J. Org. Chem. 2014, 10, 2027–2037, doi:10.3762/bjoc.10.211

• 2-hydroxy-2-(2-oxo-1-phenylethyl)malonate (2a) was prepared according to the reported procedure [54] and obtained as orange oil. The synthesis was carried out twice, once using L-proline (82%), once using 1 as catalyst (79%). Diethyl 2-hydroxy-2-(1-oxobutan-2-yl)malonate (2b) was prepared according

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• anions such as hydrogen phosphate and sulfate (buffered solutions), tartrate, succinate and malonate (unbuffered solutions). These anions changed the mode of photodegradation of RF and caused intramolecular photoaddition via the RF-divalent anion complex formation along with the normal photolysis

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• = 0.1033 (all data) and R1 = 0.0376 for 3207 reflections with I ≥ 2σ, GOF = 1.061. Dimethyl (Z)-2-((3-methoxy-3-oxo-1-phenylprop-1-en-1-yl)imino)malonate (4b) Compound 4b (164 mg, 54%; 61% based on consumed isoxazole) was obtained from isoxazole 1f (175 mg, 1.00 mmol), diazo ester 2c (159 + 63 mg, 1.40

An economical and safe procedure to synthesize 2-hydroxy-4-pentynoic acid: A precursor towards ‘clickable’ biodegradable polylactide

• Quanxuan Zhang,
• Hong Ren and
• Gregory L. Baker

Beilstein J. Org. Chem. 2014, 10, 1365–1371, doi:10.3762/bjoc.10.139

• synthetic route to prepare 1 using cheap and commercially available diethyl 2-acetamidomalonate (4) and propargyl alcohol. The desired product 1 was obtained via alkylation of malonate 4 with propargyl tosylate followed by a one-pot four-step sequence of hydrolysis, decarboxylation, diazotization and

• hydroxylation of propargylic malonate 5 without work-up of any intermediate. Keywords: alkylation; ‘click’ chemistry; ‘clickable’ polylactide; decomposition; diethyl 2-acetamidomalonate; 2-hydroxy-4-pentynoic acid; one-pot; optimization; propargyl bromide; propargyl tosylate; safe and economical; Introduction

• with low cost. Malonate has a low pKa of ~13 and can be easily deprotonated and alkylated by mild bases such as sodium/potassium alkoxides without deprotonating a terminal alkyne. Conveniently, both malonate and propargyl alcohol are commercially available in bulk quantities. Herein, we report one

Synthesis of 1-[bis(trifluoromethyl)phosphine]-1’-oxazolinylferrocene ligands and their application in regio- and enantioselective Pd-catalyzed allylic alkylation of monosubstituted allyl substrates

• Zeng-Wei Lai,
• Rong-Fei Yang,
• Ke-Yin Ye,
• Hongbin Sun and
• Shu-Li You

Beilstein J. Org. Chem. 2014, 10, 1261–1266, doi:10.3762/bjoc.10.126

• over six months under ambient atmosphere. To test the suitability of these 1-[bis(trifluoromethyl)phosphine]-1’-oxazolinylferrocene ligands in Pd-catalyzed allylic alkylation reactions, we began our study by choosing methyl cinnamyl carbonate and dimethyl malonate as the model substrates, along with

• Pd-catalyzed allylic alkylation of cinnamyl carbonate with dimethyl malonate afforded the linear product as the major product (b/l: 40/60). Whereas the corresponding ligand L1d with two CF3 groups (instead of two phenyl groups) at the P atom improved the regioselectivity significantly (b/l: 96/4). A

Aza-Diels–Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome

• Amitabh Jha,
• Ting-Yi Chou,
• Zainab ALJaroudi,
• Bobby D. Ellis and
• T. Stanley Cameron

Beilstein J. Org. Chem. 2014, 10, 848–857, doi:10.3762/bjoc.10.81

• N-aryl-3-hydroxyisoindolinones with diethyl malonate and subsequent hydrolysis, decarboxylation and Friedel–Crafts acylation sequence also result in the formation of isoindolo[2,1-a]quinolones [16][17]. N-aryl-3-hydroxyisoindolinones with an aptly positioned alkene moiety at the ortho position of

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)

• Armin Tröger,
• Teris A. van Beek,
• Martinus E. Huigens,
• Isabel M. M. S. Silva,
• Maarten A. Posthumus and
• Wittko Francke

Beilstein J. Org. Chem. 2014, 10, 767–773, doi:10.3762/bjoc.10.72

• with malonate and another methylmalonate (including deoxygenation steps) seemed to be plausible [16]. These biogenetic considerations excluded methyl groups at positions 9 and 11. To prepare a mixture of all stereoisomers of 14, we again used 2 as the starting material (Figure 2). Monobenzylation to 9

• ]. Location at position 2 would provide 14, which was already ruled out. According to a conceivable biosynthesis of the natural product from methylmalonate and acetate, positions 3 and 5 would be less favourable [16]. However, linear condensation of five methylmalonate units and a final malonate (and again

Phosphinate-containing heterocycles: A mini-review

• Olivier Berger and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2014, 10, 732–740, doi:10.3762/bjoc.10.67

• malonate anion. Tandem hydrophosphinylation/Michael/Michael reaction of allenyl-H-phosphinates. 5-Membered “cyclo-PALA” via intramolecular Mitsunobu reaction. 6-Membered “cyclo-PALA” via intramolecular Mitsunobu reaction. Intramolecular Kabachnik–Fields reaction. Tandem Kabachnik–Fields/alkylation reaction

A novel family of (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids – analogues of α-amino acids

• Natalia V. Pavlenko,
• Tatiana I. Oos,
• Yurii L. Yagupolskii,
• Igor I. Gerus,
• Uwe Doeller and
• Lothar Willms

Beilstein J. Org. Chem. 2014, 10, 722–731, doi:10.3762/bjoc.10.66

• to the activated C=C double bond of malonate 38 followed by hydrolysis and decarboxylation to generate adduct 39 in two steps (Scheme 10). Conclusion In conclusion, we have presented a variety of approaches to novel fluorinated (1-aminoalkyl)phosphinic acids starting from the appropriate fluorinated

IBD-mediated oxidative cyclization of pyrimidinylhydrazones and concurrent Dimroth rearrangement: Synthesis of [1,2,4]triazolo[1,5-c]pyrimidine derivatives

• Caifei Tang,
• Zhiming Li and
• Quanrui Wang

Beilstein J. Org. Chem. 2013, 9, 2629–2634, doi:10.3762/bjoc.9.298

• investigation commenced with the preparation of 1-(6-chloropyrimidin-4-yl)hydrazines 3. The required starting 4,6-dihydroxypyrimidines 1 can be prepared following the reported procedure by condensation of dimethyl malonate either with formamide (for 1a) or the respective formamidine salts (for 1b and 1c) [15

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

Synthesis and antibacterial activity of monocyclic 3-carboxamide tetramic acids

• Yong-Chul Jeong and
• Mark G. Moloney

Beilstein J. Org. Chem. 2013, 9, 1899–1906, doi:10.3762/bjoc.9.224

• equiv), EtOH, reflux; (b) monoethyl malonate (1.1 equiv), DCC (1.1 equiv), CH2Cl2, rt; (c) NaOMe (1.1 equiv), benzene, EtOH, reflux; (d) RNH2 (1.0 equiv), toluene, reflux. Synthesis of N-alkyl 3-carboxamide tetramic acid. Reaction conditions: (a) 1. glycine methyl ester∙HCl (1.0 equiv), Et3N (1.2 equiv

The preparation of several 1,2,3,4,5-functionalized cyclopentane derivatives

• André S. Kelch,
• Peter G. Jones,
• Ina Dix and
• Henning Hopf

Beilstein J. Org. Chem. 2013, 9, 1705–1712, doi:10.3762/bjoc.9.195

• acetylenedicarboxylate (22) with dimethyl malonate (23) under the catalytic influence of pyridinium acetate, the fully substituted cycloheptadienes 24 and 25 (Scheme 5) were produced; both authors also proposed reaction mechanisms for this complex transformation that can be considered as reasonable even today; for the

Preparation and ring-opening reactions of N-diphenylphosphinyl vinyl aziridines

• Ashley N. Jarvis,
• Andrew B. McLaren,
• Helen M. I. Osborn and
• Joseph Sweeney

Beilstein J. Org. Chem. 2013, 9, 852–859, doi:10.3762/bjoc.9.98

• with ethyl acetate/light petroleum (1:1) as an eluent. Palladium-catalyzed ring-opening with malonate: To diethyl malonate (typically 0.3–0.6 mmol, 1.1 equiv) in THF (1.5 mL), at room temperature, under argon, was added sodium hydride (1.1 equiv), and the colourless solution was left to stir for 30 min

Quantification of N-acetylcysteamine activated methylmalonate incorporation into polyketide biosynthesis

• Stephan Klopries,
• Uschi Sundermann and
• Frank Schulz

Beilstein J. Org. Chem. 2013, 9, 664–674, doi:10.3762/bjoc.9.75

• starter unit diversity [18][19][20] were in several instances introduced, giving rise to a significant number of polyketide derivatives to date. However, the accessible extender unit diversity is currently restricted to a small number of different malonate units and changes in the polyketide side chain

• by using various different strategies. Subsequently, thioester activated non-native malonate derivatives can be synthesized by additional heterologously expressed biosynthetic pathways leading to the respective derivative of malonyl-CoA [17] or malonyl-ACP [27], which are supplied in vivo to the

• mutated PKS. Another option is the exogenous supply of the malonate derivative [28], typically activated as N-acetylcysteamine thioesters (malonyl-SNAC) [29][30][31][32][33][34][35][36][37][38][39][40]. Despite its apparent simplicity, the latter option is not well characterized for in vivo applications

A new synthetic protocol for coumarin amino acid

• Xinyi Xu,
• Xiaosong Hu and
• Jiangyun Wang

Beilstein J. Org. Chem. 2013, 9, 254–259, doi:10.3762/bjoc.9.30

• to 5c, respectively, if sodium hydride was used). In the presence of potassium tert-butoxide and a catalytic amount of tetrabutylammonium bromide, alkene 5 reacted with diethyl acetamidomalonate (DEAM) [13] to form malonate 6 in high yield (6a, 73.1% yield; 6b, 86.0%; 6c, 86.0%). It was then heated

• reaction of DEAM to terminal alkene 5, malonate 6 was formed in high yield, and it was followed by the total hydrolysis of compound 6 with concentrated aqueous HCl solution to afford the coumarin amino acid 1. We found that the hydrolysis needed a high concentration of aqueous HCl solution (12 M) and a

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• to 5.3:1 dr and 91–99% ee. The solvent-free ball-milling of dimethyl malonate with nitrostyrene in the presence of IX provides the corresponding Michael adduct in 80% yield and 91% ee. However, chiral squaramide catalysed Michael addition of dicarbonyl compounds to nitroalkenes in dichloromethane by

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

• Andrew Tigchelaar and
• William Tam

Beilstein J. Org. Chem. 2012, 8, 1765–1770, doi:10.3762/bjoc.8.201

• %), respectively. Synthesis of substrate 1g commenced with deprotonation of diethyl malonate, followed by addition of mesylate 12, and subsequent deprotonation and addition of propargyl bromide as described by Gilbertson [31] to provide dieneyne 13 (Scheme 4). Diene 13 was then treated under the standard

Influence of cyclodextrin on the solubility of a classically prepared 2-vinylcyclopropane macromonomer in aqueous solution

• Helmut Ritter,
• Jia Cheng and
• Monir Tabatabai

Beilstein J. Org. Chem. 2012, 8, 1528–1535, doi:10.3762/bjoc.8.173

• (4) was synthesized following a procedure described in [32]. Diethyl 2-vinyl-1,1-cyclopropanedicarboxylate could be obtained according to [33] from sodium ethoxide, diethyl malonate and trans-1,4-dichloro-2-butene in ethanol (Scheme 2). The desired macromonomer 5 was prepared in two steps according

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

• Tatyana E. Shubina,
• Matthias Freund,
• Sebastian Schenker,
• Timothy Clark and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

• Organic Chemistry I, University of Erlangen-Nuremberg, Henkestraße 42, 91054, Erlangen, Germany 10.3762/bjoc.8.168 Abstract A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene

• of diethyl malonate (14) to nitrostyrene (11) and to find a plausible explanation as to why the enantioselectivity of this reaction is low. As a first step, we explored the conformational flexibility of the catalyst 7 itself. Pápai and co-workers [57] studied a similar dimethylaminothiourea catalyst

• not considered for the further studies. A similar Michael reaction of 1,3-dicarbonyl compounds with nitroolefins has been studied in some detail before [57][59]. It is generally proposed that the reaction proceeds first by deprotonation of the acidic proton of malonate 14 followed by formation of a

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones

• Sergei Žari,
• Tiiu Kailas,
• Marina Kudrjashova,
• Mario Öeren,
• Ivar Järving,
• Toomas Tamm,
• Margus Lopp and
• Tõnis Kanger

Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165

• catalysts were screened in the reaction of phenyl disubstituted unsaturated 1,4-diketone 1a with diethyl malonate (2a, Table 1). The reaction was run in DCE at room temperature in the presence of 10 mol % of catalyst with a five-fold excess of malonate. In all cases, the yields of the products were very

• , which may possibly allow additional interactions with the aromatic substrates 1, the catalyst IX was also chosen. Scope of the reaction Next, we studied the effect of the malonate structure on the stereoselectivity of the reaction (Table 2). Although, the ester moiety can be replaced by other functional

• groups in the course of further synthetic transformations its main role is to provide the addition products with high ee value. The conditions for the reaction remained the same as they were in the catalyst screening experiments, except that a smaller excess of malonate (3 equiv, unless stated otherwise

Synthesis of a novel chemotype via sequential metal-catalyzed cycloisomerizations

• Bo Leng,
• Stephanie Chichetti,
• Shun Su,
• Aaron B. Beeler and
• John A. Porco Jr.

Beilstein J. Org. Chem. 2012, 8, 1338–1343, doi:10.3762/bjoc.8.153

• processes and chemotypes [5]. For example, we have conducted multidimensional reaction screens using alkynyl o-benzaldehyde scaffolds, which revealed a number of reactions affording novel polycyclic scaffolds, including Au(III)-catalyzed addition of diethyl malonate to 1 to afford isochromene 2 (Scheme 1

• , evaluating a number of metal catalysts in the presence of diethyl malonate. From this focused reaction screen we identified three types of reactivity: (1) no reaction; (2) alkyne hydration (4); and (3) cycloisomerization leading to isochromene (5) (Figure 1). Many catalysts resulted in no reaction, including

• diynyl benzaldehyde 3 and dimethyl malonate is catalyzed by Cu(I) to afford isochromene 24 [20][21][22]. Pt(II) π-coordination of the pendant alkyne of 24 followed by cyclization of the enol ether affords the seven-membered-ring metal-“ate” intermediate 25. The cyclization occurs at the face opposite the

Combined bead polymerization and Cinchona organocatalyst immobilization by thiol–ene addition

• Kim A. Fredriksen,
• Tor E. Kristensen and
• Tore Hansen

Beilstein J. Org. Chem. 2012, 8, 1126–1133, doi:10.3762/bjoc.8.125

• also tested in the Michael addition of methyl malonate to trans-β-nitrostyrene (Table 4) [21]. The catalyst gave quantitative yield and excellent enantioselectivity after 3–4 days reaction time. However, the catalyst exhibited poor recycling properties as yields fell sharply after the second reaction

• determined by HPLC analysis (Chiralpak AD-H, 2% iPrOH in isohexane, 1.0 mL/min): tR = 19.2 min and 26.2 min. General procedure for asymmetric Michael addition of methyl malonate to trans-β-nitrostyrene: trans-β-Nitrostyrene (83.4 mg, 0.56 mmol) and methyl malonate (0.23 g, 1.78 mmol) were dissolved in