Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

• Felicia D’Andrea,
• Giorgio Catelani,
• Lorenzo Guazzelli and
• Venerando Pistarà

Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227

• the absence of a coordinating metal center (for instance, in the case of tin and zirconium enolates, and of “naked” enolates generated from enolsilanes [42]). In the open-transition-state model, the enolate and the carbonyl group are orientated in an antiperiplanar fashion, maximazing the distance

Cross-linked cyclodextrin-based material for treatment of metals and organic substances present in industrial discharge waters

• Élise Euvrard,
• Nadia Morin-Crini,
• Coline Druart,
• Justine Bugnet,
• Bernard Martel,
• Cesare Cosentino,
• Virginie Moutarlier and
• Grégorio Crini

Beilstein J. Org. Chem. 2016, 12, 1826–1838, doi:10.3762/bjoc.12.172

• such as cross polarization magic angle spinning (CP MAS) and MAS. The spectra were recorded with a Bruker spectrometer operating at 75.47 MHz and 303 K. The compounds were placed in a zirconium rotor, 4 mm in diameter and 21 mm high. The chemical shifts were recorded relative to tetramethylsilane with

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• methacrylonitrile (Figure 4) [70][71][72][73][74]. Other researchers have reported platinum [75], nickel [76], and zirconium [77] catalysts for the hydrophosphination and hydroamination of methacrylonitrile; however, these examples provided product with significantly lower enantioselectivity. In 2004, the Togni lab

Scope and mechanism of the highly stereoselective metal-mediated domino aldol reactions of enolates with aldehydes

• M. Emin Cinar,
• Bernward Engelen,
• Martin Panthöfer,
• Hans-Jörg Deiseroth,
• Jens Schlirf and
• Michael Schmittel

Beilstein J. Org. Chem. 2016, 12, 813–824, doi:10.3762/bjoc.12.80

• reaction was already successful with two equivalents of enolate per metal fragment. However, higher yields were obtained at higher loadings. For example, zirconium worked best with three enolate units and tin with four. Surprisingly, an excess of an enolate had different effects on the reactions depending

• on the metals. While the yield was decreased with zirconium, it increased both with aluminum and indium. In the latter case, >99% yield was obtained. In the same manner the influence of the amount of aldehyde was examined. As can be seen from the data in Table 3 the ratio of 5a to 6a decreases

• preorganization, which is necessary for the reaction. The reactions carried out with 1.0, 0.75 and 0.5 equivalents of zirconium provided 5a in 76, 42 and 14% yield, respectively. Reducing the amount to 0.25 equivalents of zirconium furnished only 3% yield. Even the concentration influences the yield of 5a. The

Aluminacyclopentanes in the synthesis of 3-substituted phospholanes and α,ω-bisphospholanes

• Vladimir A. D’yakonov,
• Alevtina L. Makhamatkhanova,
• Rina A. Agliullina,
• Leisan K. Dilmukhametova,
• Tat’yana V. Tyumkina and
• Usein M. Dzhemilev

Beilstein J. Org. Chem. 2016, 12, 406–412, doi:10.3762/bjoc.12.43

• with molybdenum hexacarbonyl. The structure of the complexes was proved by multinuclear 1H, 13C, and 31P spectroscopy. Keywords: aluminacyclopentanes; Dzhemilev reaction; molybdenum complexes; phospholanes; zirconium complexes; Introduction A widely used approach for the synthesis of cyclic

Regioselective palladium-catalyzed ring-opening reactions of C1-substituted oxabicyclo[2,2,1]hepta-2,5-diene-2,3-dicarboxylates

• Michael Edmunds,
• Mohammed Abdul Raheem,
• Rebecca Boutin,
• Katrina Tait and
• William Tam

Beilstein J. Org. Chem. 2016, 12, 239–244, doi:10.3762/bjoc.12.25

• % respectively (Table 1, entries 9 and 4). The Lewis acid additives gave a large range of yields (Table 1, entries 10–14). Iron and aluminium chlorides gave low yields (22%, Table 1, entry 10 and 29%, entry 11), zirconium chloride and zinc iodide gave moderate yields (47%, Table 1, entry 12 and 48%, entry 13

Copper-catalysed asymmetric allylic alkylation of alkylzirconocenes to racemic 3,6-dihydro-2H-pyrans

• Emeline Rideau and
• Stephen P. Fletcher

Beilstein J. Org. Chem. 2015, 11, 2435–2443, doi:10.3762/bjoc.11.264

• ][17][18]. We have developed Cu-catalysed asymmetric conjugate additions of alkylzirconium reagents generated in situ by hydrometallation of terminal alkenes [19][20][21][22][23][24][25], and recently demonstrated that zirconium nucleophiles may undergo highly enantioselective copper-catalysed AAAs to

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• , new approaches were developed including zinc, zirconium and copper reagents. Polyfunctional alkenylphosphine 65 was accessible via the reaction of organozinc derivative 64 with chlorophosphine 22a. The organozinc bromide 64 was prepared from the corresponding alkenyl iodide 63. To prevent oxidation

Integration of enabling methods for the automated flow preparation of piperazine-2-carboxamide

• Richard J. Ingham,
• Claudio Battilocchio,
• Joel M. Hawkins and
• Steven V. Ley

Beilstein J. Org. Chem. 2014, 10, 641–652, doi:10.3762/bjoc.10.56

• –Ponndorf–Verley reductions [22] and Oppenauer oxidations [23] where zirconia activation is required). In fact, it seems that the extent of hydration of pyrazine-2-carbonitrile is proportional to the initial water content of the zirconium catalyst. To confirm this hypothesis, we ran a control experiment in

• which no additional water was added to the organic solvent (absolute ethanol). A solution of 3 was continuously fed into a reactor column containing untreated zirconium hydroxide [25]. The reaction profile was followed with an in-line infrared (IR) spectrometer in order to determine the conversion

• , solutions of nitrile 3 were passed through heated column reactor R1 (Omnifit® glass column, 100 mm × 6.6 mm; a flow rate of 0.1 mL min−1 produced a residence time of 20 minutes) packed with 2.5 g of zirconium hydroxide. (Due to the practicalities involved with performing reactions using different solvents

Zirconoarylation of alkynes through p-chloranil-promoted reductive elimination of arylzirconates

• Xiaoyu Yan,
• Chao Chen and
• Chanjuan Xi

Beilstein J. Org. Chem. 2014, 10, 528–534, doi:10.3762/bjoc.10.48

• alkynes have been reported. Most of the carbometal reagents, which were used, contained Li, Mg, Cu, Zn, B, or Al [12][13][14][15][16]. In the last several decades also zirconium-mediated or -catalyzed organic reactions have been extensively investigated [37][38][39]. In addition, a series of organic

• aryllithium compounds were coupled in one-pot in the presence of Cp2Zr species to afford highly substituted 1,3-butadienes. The pathway of the oxidation of zirconate 2 to vinylzirconocene 4 is not yet clear. A possible mechanism is proposed in Scheme 6. Coordination of TCQ to zirconium results in reductive

Silica: An efficient catalyst for one-pot regioselective synthesis of dithioethers

• Samir Kundu,
• Babli Roy and
• Basudeb Basu

Beilstein J. Org. Chem. 2014, 10, 26–33, doi:10.3762/bjoc.10.5

• and also as spacers in metal-organic frameworks [9][10][11][12][13][14]. For example, vicinal dithioether-based zirconium and titanium complexes have been used for alkene polymerization and hydroamination [15][16][17][18]. Chiral dithioethers have been prepared and their iridium complexes have been

Total synthesis of the endogenous inflammation resolving lipid resolvin D2 using a common lynchpin

• John Li,
• May May Leong,
• Alastair Stewart and
• Mark A. Rizzacasa

Beilstein J. Org. Chem. 2013, 9, 2762–2766, doi:10.3762/bjoc.9.310

• stereoisomer analogues of RvD2 (1). Removal of the TIPS group with TBAF gave terminal alkyne 12. Alkyne 12 then underwent smooth hydrozirconation utilizing the procedure reported by Negishi [24] were ZrCp2HCl is generated in situ by reduction of ZrCp2Cl2 with DIBALH in THF. Iodinolysis of the zirconium species

Synthesis of the spiroketal core of integramycin

• Evgeny. V. Prusov

Beilstein J. Org. Chem. 2013, 9, 2446–2450, doi:10.3762/bjoc.9.282

• optimization of this reaction. In summary, an efficient route to the C16–C35 spiroketal fragment of integramycin was developed. The key step of the synthesis is a Cu-catalysed coupling of an acid chloride with an alkyl zirconium species. The stereocenters were introduced using Leighton crotylation, Sharpless

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• zirconium salt, the examples of transition-metal-catalyzed carbometalation of dialkylacetylenes were limited only to carboboration [109][110] and carbostannylation [111]. In 2005, Shirakawa and Hayashi reported iron/copper-cocatalyzed arylmagnesiation of dialkylacetylenes [112]. This is the first successful

• 2000, Negishi reported zirconium-catalyzed ethylzincation of 1-decene to provide dialkylzinc intermediate 4h (Scheme 41) [123]. Intermediate 4h reacted with iodine to provide alkyl iodide 4i in 90% yield. The carbozincation reaction is cleaner and affords the corresponding products in high yields

• compared with the reported carbomagnesiation reactions [124][125][126][127][128][129]. Hoveyda reported zirconium-catalyzed alkylmagnesiation reactions of styrene in 2001 by using primary or secondary alkyl tosylates as alkyl sources [130]. The reactions proceeded through zirconacyclopropane 4F as a key

Intramolecular carbolithiation of N-allyl-ynamides: an efficient entry to 1,4-dihydropyridines and pyridines – application to a formal synthesis of sarizotan

• Wafa Gati,
• Mohamed M. Rammah,
• Mohamed B. Rammah and
• Gwilherm Evano

Beilstein J. Org. Chem. 2012, 8, 2214–2222, doi:10.3762/bjoc.8.250

• the carbometallation of various carbon–carbon multiple bonds. Lithium, copper, zinc, magnesium, zirconium, titanium, palladium and other metals are suitable for this transformation and considerable progress has recently been made in this area. Among these systems, the carbometallation of alkynes

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

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

• substituents has been prepared recently by a Zr-promoted linear coupling of different aryl and hetaryl acetylenes in high yield (Scheme 17) [66]. Treating, e.g., phenylacetylene (78) first with n-butyllithium and subsequently with bis(cyclopentadienyl)zirconium dichloride generates the trimeric metal complex

Metal–ligand multiple bonds as frustrated Lewis pairs for C–H functionalization

• Matthew T. Whited

Beilstein J. Org. Chem. 2012, 8, 1554–1563, doi:10.3762/bjoc.8.177

• role, as one can envision a bimolecular pathway to acid–base adduct formation (Figure 2a). Such dimerization does occur in cases with insufficient steric encumbrance (e.g., the bis-μ-imido zirconium complexes of Bergman, Figure 2b) [25]. Thus, as for the main-group FLPs of Stephan and others

• ) [27]. Similar reactions have been observed for nucleophilic imido complexes, in which imines can be formed by an oxo/imide metathesis at zirconium(IV). As with the Schrock neopentylidene, the reaction proceeds through a four-membered metallacycle, which eliminates the organic product through a [2 + 2

• ) and related variants such as alkyne and enyne metathesis [36][37]. Related reactivity is prevalent for other Mδ+═Eδ− species such as imides and nitrides. Bergman's bis(cyclopentadienyl)zirconium(IV) imides, described above, will add alkenes and alkynes in [2 + 2] fashion across the Zr═NR bond (Scheme

Development of the titanium–TADDOLate-catalyzed asymmetric fluorination of β-ketoesters

• Lukas Hintermann,
• Mauro Perseghini and
• Antonio Togni

Beilstein J. Org. Chem. 2011, 7, 1421–1435, doi:10.3762/bjoc.7.166

• , entry 2), whereas the corresponding zirconium complex was inactive (Table 1, entry 3). Both the Brønsted acid HBF4 and the Lewis acid BF3 accelerated the reaction. Substrate 2 with a higher tendency towards enolization (Figure 2) gave higher conversions, but a similar trend. Interestingly, the

Homoallylic amines by reductive inter- and intramolecular coupling of allenes and nitriles

• Peter Wipf and
• Marija D. Manojlovic

Beilstein J. Org. Chem. 2011, 7, 824–830, doi:10.3762/bjoc.7.94

• ][9]. Similar to the related alkyl- and alkenyl- zirconocenes [1][2][3][6], this limitation of sterically hindered allylzirconocene complexes can be overcome by selective transmetalation of zirconium to other metals. Suzuki and co-workers treated allylzirconocenes with methylaluminoxane (MAO) in order

• desired product formation in good yield and provided a single diastereoisomer. This observation is in agreement with previous work in our group that showed the transmetalation from zirconium to zinc to occur faster in toluene than in CH2Cl2 [15]. Furthermore, we also repeated some earlier examples of the

SbCl₃-catalyzed one-pot synthesis of 4,4′-diaminotriarylmethanes under solvent-free conditions: Synthesis, characterization, and DFT studies

• Ghasem Rezanejade Bardajee

Beilstein J. Org. Chem. 2011, 7, 135–144, doi:10.3762/bjoc.7.19

• acids such as zinc chloride, zeolites, montmorillonite K-10, and polymer-supported sulfonic acid (NKC-9) [35][36][37][38][39][40]. Microwave-assisted synthesis of DTMs in the presence of aniline hydrochloride has also been described [41]. Recently, bismuth(III) nitrate and zirconium(IV) dichloride oxide

Functionalized copolyimide membranes for the separation of gaseous and liquid mixtures

• Nadine Schmeling,
• Roman Konietzny,
• Daniel Sieffert,
• Patrick Rölling and
• Claudia Staudt

Beilstein J. Org. Chem. 2010, 6, 789–800, doi:10.3762/bjoc.6.86

• groups reduces the CO2 plasticization slightly due to the hydrogen bonds between the carboxylic acid groups [23]. Copolyimides with carboxy groups can be further modified via covalent cross-linking with, e.g., diols or diamines or cross-linked ionically with aluminium acetylacetonate or zirconium

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

Asymmetric aza-Diels- Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

• Bruce Pégot,
• Olivier Nguyen Van Buu,
• Didier Gori and
• Giang Vo-Thanh

Beilstein J. Org. Chem. 2006, 2, No. 18, doi:10.1186/1860-5397-2-18

• relation to the asymmetric process. Among them are: the zirconium-binaphthol complexes developed by Kobayashi et al., [8][9][10][11] the silver catalysts of phosphine peptide Schiff bases reported by Snapper and Hoveyda,[12] as well as the copper complexes of BINAP and phosphino-oxazolidines described by