Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products

• Dmitry S. Ryabukhin,
• Dmitry N. Zakusilo,
• Mikhail O. Kompanets,
• Anton A.Tarakanov,
• Irina A. Boyarskaya,
• Tatiana O. Artamonova,
• Mikhail A. Khohodorkovskiy,
• Iosyp O. Opeida and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202

• temperature for 1–24 h gives rise to 5-arylmethylfurfurals (yields of 17–91%) and 2-arylmethyl-5-(diarylmethyl)furans (yields of 10–37%). The formation of these two types of reaction products depends on the nucleophilicity of the arene. The same reactions under the action of acidic zeolites H-USY in high

• compounds were formed by hydroxyalkylation due to the interaction of species A with arenes (see related reactions [34][35][36][37][38]). The polymethylated arenes possess a sufficient π-nucleophilicity for the reaction with the protonated aldehyde group of the intermediates generated from 1a in TfOH

• (Table 4, entries 20–23). Under the superacidic conditions the substrates anisole and veratrole may be protonated at the oxygen atoms [33], thus leading to a decreased π-nucleophilicity of these arenes. It should be noted that in the case of zeolites we explored CS2 as low coordinating solvent to avoid

p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates

• Madhuri Vangala and
• Ganesh P Shinde

Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197

• nucleophiles towards halo derivatives of main group elements where the DBU and DBN bicyclic rings remained unaffected [10][11]. Later in 1994, Lammers et al. observed the nucleophilicity of amidine bases with 4-halo-3,5-dimethyl-1-nitro-1H-pyrazole and their subsequent ring opening leading to the lactam

• carbohydrate–protein interactions [25], ligation and surfactant properties [26][27]. Although p-nitrophenyl carbonates were extensively utilized in these reactions, the nucleophilicity of amidine bases towards these carbonates was not encountered so far. In continuation of our interest in carbohydrates [28][29

• with DBU under the same conditions as described above, giving 6b and 7b in 82% and 87% yield, and 8b as a mixture of α and β anomers in 48% yield. Encouraged by these results, we turned to evaluate the nucleophilicity of DBN towards p-nitrophenyl carbonate derivatives (Scheme 2). Next, the reaction of

Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

• Jimena E. Díaz,
• María C. Mollo and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2016, 12, 2026–2031, doi:10.3762/bjoc.12.190

• considerably lower nucleophilicity of the arylamino group, procedures for N-alkyl or N-unsubstituted 2-iminoazacycloalkanes are usually not suitable for the synthesis of N-aryl derivatives. Ethyl polyphosphate (PPE) and trimethylsilyl polyphosphate (PPSE) are mild irreversible dehydrating agents of the Lewis

Synthesis of pyrrolo[2,1-f][1,2,4]triazin-4(3H)-ones: Rearrangement of pyrrolo[1,2-d][1,3,4]oxadiazines and regioselective intramolecular cyclization of 1,2-biscarbamoyl-substituted 1H-pyrroles

• Kkonnip Son and
• Seong Jun Park

Beilstein J. Org. Chem. 2016, 12, 1780–1787, doi:10.3762/bjoc.12.168

• to 12a, the mechanism of the nucleophile-induced cyclization is proposed after considering Hart’s research on the synthesis of fumiquinazolines [22]. It was shown that the nucleophilicity of the N-acylnitrenium ion was increased when the oxygen ion was stabilized by counter ions such as lithium and

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Catalytic Chan–Lam coupling using a ‘tube-in-tube’ reactor to deliver molecular oxygen as an oxidant

• Carl J. Mallia,
• Paul M. Burton,
• Alexander M. R. Smith,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2016, 12, 1598–1607, doi:10.3762/bjoc.12.156

• of 26% (28, Scheme 2). It is not yet clear as to why such a low conversion and isolated yield was obtained although the reduced nucleophilicity and higher potential for coordination of the triazole to the copper catalyst might inhibit catalyst turnover and account for this. Alternatively, using 3

• reactor blocking. Other substrates proved unreactive. In the case of starting materials 41–43 the reduced nucleophilicity of these substrates might account for the lack of conversion. By comparison, all three substrates (41–43) also failed to react under batch conditions using 2 equiv of Cu(OAc)2, 2 equiv

On the cause of low thermal stability of ethyl halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155

• nucleophilicity can be inferred from the NBO charges. Based only on NBO charges, halodiazoacetates may be expected to be even less nucleophilic than diethyl diazomalonate (see Supporting Information File 2 for the numbers). All of the investigated diazo compounds thermally extrude N2 to initially form a singlet

• temperature for 30 min. The solvent was removed and the crude product was purified by silica gel chromatography (5% EtOAc/hexane) to give 123 mg (0.457 mmol, 67%) of ethyl 1-bromo-2-phenylcyclopropanecarboxylate as a colorless oil. Relative stability and nucleophilicity of non-stabilized (R = H, alkyl) diazo

• halodiazoacetates (red color). Relative nucleophilicity of halodiazoacetates (red color). Synthesis of ethyl halodiazoacetates [11]. Proposed rate determining step for the thermal decomposition of 2a–c. Reaction conditions and half-lives (t1/2) of 2a–c. Cyclopropanation of styrenes with 2a–c. Supporting

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• diferrocenyl derivative Cr(CO)5(E-2) from bulky Fc-NH2 [40][41] requires the presence of a base to increase the nucleophilicity of Fc-NH2 by deprotonation. In the presence of base, Cr(CO)5(E-2) decomposes readily in solution at room temperature releasing E-1,2-diferrocenylimine [43] E-3 (Scheme 1a) [27]. Base

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

• cyclic N-benzyloxycarbonyl acrylamides 75 and 77 in moderate to good yields and high enantioselectivity (Scheme 18a,b). Due to their attenuated nucleophilicity, electron-deficient amines were unreactive under the standard reaction conditions. Addition of 0.5 equivalents of free amine was found to be

Recent advances in C(sp³)–H bond functionalization via metal–carbene insertions

• Bo Wang,
• Di Qiu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2016, 12, 796–804, doi:10.3762/bjoc.12.78

• selectivity. The factors governing the reactivity and site-selectivity of metal–carbene C–H insertion include: 1) the electrophilicity of the metal–carbene bond; 2) the nucleophilicity of the targeted C–H bond; 3) the steric bulk of the ligand around the metal; 4) the steric bulk of the substituents around

Interactions of cyclodextrins and their derivatives with toxic organophosphorus compounds

• Sophie Letort,
• Sébastien Balieu,
• William Erb,
• Géraldine Gouhier and
• François Estour

Beilstein J. Org. Chem. 2016, 12, 204–228, doi:10.3762/bjoc.12.23

• hydrogen bonding between the secondary OH groups of the CD and the reactive site of the guest. Indeed, such interactions increase the nucleophilicity of the secondary hydroxy groups and facilitate their attack onto the phosphorus atom. Indeed, when the para-nitrophenoxy moiety is deeply included into the

Scope and limitations of the dual-gold-catalysed hydrophenoxylation of alkynes

• Adrián Gómez-Suárez,
• Yoshihiro Oonishi,
• Anthony R. Martin and
• Steven P. Nolan

Beilstein J. Org. Chem. 2016, 12, 172–178, doi:10.3762/bjoc.12.19

• nucleophilicity decreases and an increase in catalyst loading is needed in order to maintain relatively short reaction times (3ai and 3al) [31]. The steric hindrance on the phenol was studied next. Increasing it, with either allyl (3am) or tert-butyl (3an) groups on the ortho-position also required 1 mol % of

Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation

• Jochen Kraft,
• Martin Golkowski and
• Thomas Ziegler

Beilstein J. Org. Chem. 2016, 12, 166–171, doi:10.3762/bjoc.12.18

• ester 11 as boron source (Scheme 2) [22][23][24]. 2-Pyridineboronic acid 11 was chosen due to its increased nucleophilicity compared to other boron sources like pinacol boronic esters or MIDA boronates [25][26]. The cross coupling proceeded smoothly in THF and gave ligands 9 and 10 in good yields

Catalytic asymmetric formal synthesis of beraprost

• Yusuke Kobayashi,
• Ryuta Kuramoto and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2015, 11, 2654–2660, doi:10.3762/bjoc.11.285

• condensation followed by diazo-transfer reaction. The chiral dihydrobenzofuran scaffold (5 or 6) could be synthesized by asymmetric intramolecular oxa-Michael reaction (AIOM) of α,β-unsaturated amides 7 or 8. Such reactions are generally considered to be challenging due to low nucleophilicity of the oxygen

Synthesis of D-fructose-derived spirocyclic 2-substituted-2-oxazoline ribosides

• Madhuri Vangala and
• Ganesh P. Shinde

Beilstein J. Org. Chem. 2015, 11, 2289–2296, doi:10.3762/bjoc.11.249

• corresponding products 16a and 17a in moderate yields. Finally, 2-cyanothiophene (Table 1, entry 13) also reacted with 5a to give 18a in 45% yield. Further, 4-nitrobenzonitrile and 2-cyanopyridine with an electron-withdrawing group or ring did not give the expected product due to the reduced nucleophilicity of

Convenient preparation of high molecular weight poly(dimethylsiloxane) using thermally latent NHC-catalysis: a structure-activity correlation

• Stefan Naumann,
• Johannes Klein,
• Dongren Wang and
• Michael R. Buchmeiser

Beilstein J. Org. Chem. 2015, 11, 2261–2266, doi:10.3762/bjoc.11.246

• , emphasizing that nucleophilicity is crucial for successful polymerization. Furthermore, it is interesting to note that the six- and seven-membered NHCs do not show any reactivity here, in spite of being very strong bases. While for a compound like 6-iPr a pKa-value of 28.2 (aqueous solution, 25 °C) was found

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• , a deprotonation of the metallacyclobutane is hypothesized to explain the amine-induced decomposition (Table 3). Consequently, a modulation of the Brønsted basicity and/or the nucleophilicity of the amine/N-heteroaromatic present on an alkene may allow its use in metathesis reactions. Ring-closing

• examples of successful RCM involving alkenes containing N-heteroaromatics, it seems that decreasing their Brønsted basicity and/or their nucleophilicity through the introduction of suitable electron-withdrawing and/or bulky substituents may prevent the catalyst deactivation thus allowing the metathesis to

• hindrance next to the nitrogen atom could also play a role by decreasing the nucleophilicity of the nitrogen as attested by the formation of alkene 98f in a moderate 52% yield (Scheme 36). This strategy was applied to the formation of a broad variety of disubstituted olefins containing N-heteroaromatic

New aryloxybenzylidene ruthenium chelates – synthesis, reactivity and catalytic performance in ROMP

• Patrycja Żak,
• Szymon Rogalski,
• Mariusz Majchrzak,
• Maciej Kubicki and
• Cezary Pietraszuk

Beilstein J. Org. Chem. 2015, 11, 1910–1916, doi:10.3762/bjoc.11.206

• nucleophilicity of the phosphine ligands. A strong electronic influence of the substituent in the ring of the phenoxybenzylidene ligand, in para position towards the oxygen atom, on the catalytic activity of the active form of the complexes was found. The presence of an electron-donating tert-butyl substituent

Pd(OAc)₂-catalyzed dehydrogenative C–H activation: An expedient synthesis of uracil-annulated β-carbolinones

• Biplab Mondal,
• Somjit Hazra,
• Tarun K. Panda and
• Brindaban Roy

Beilstein J. Org. Chem. 2015, 11, 1360–1366, doi:10.3762/bjoc.11.146

• mechanistic pathway that commence with electrophilic metalation at the indole C3 postion. The nucleophilicity of indole at C3 is well known [58] and a similar kind of electrophilic reaction leads to the intermediate A (Scheme 3). We believe this intermediate then undergoes a σ-bond metathesis reaction to form

Surprisingly facile CO₂ insertion into cobalt alkoxide bonds: A theoretical investigation

• Willem K. Offermans,
• Claudia Bizzarri,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 1340–1351, doi:10.3762/bjoc.11.144

• crystal solid-state structure reported for [CoIII(salen)(dinitrophenolate)] [49]. The distance between cobalt and the oxygen atom of the alkoxide chain was 1.9–1.94 Å, with a small yet systematic variation in dependence on the nucleophilicity of L. The more nucleophilic L was, the longer the Co–OR

• varied from 1.99 Å to 1.93 Å depending on the nucleophilicity of L: the less nucleophilic the ligand L was, the shorter the CoIII–O bond was. The carbon–oxygen bond lengths within the carbonate unit were 1.294(5) Å for C1–O3, 1.236(3) Å for C1–O4, and 1.392(11) Å for C1–O5, with only little variation in

• the cobalt–carbonate bond is stronger than the cobalt–alkoxide bond. Since the alkoxide is a stronger Lewis base than the carbonate, we calculated an increase in bond strength between the carbonate unit and cobalt center with respect to the cobalt(III)–alkoxide bond, depending on the nucleophilicity

Highly selective palladium–benzothiazole carbene-catalyzed allylation of active methylene compounds under neutral conditions

• Antonio Monopoli,
• Pietro Cotugno,
• Carlo G. Zambonin,
• Francesco Ciminale and
• Angelo Nacci

Beilstein J. Org. Chem. 2015, 11, 994–999, doi:10.3762/bjoc.11.111

• of the different behavior displayed by these two carbene ligands can be found in the different aromatic character of their (benzothiazole and imidazole) heterocyclic rings. It is well known that this feature can strongly affect the nucleophilicity of these NHC species, and ultimately can influence

An intramolecular C–N cross-coupling of β-enaminones: a simple and efficient way to precursors of some alkaloids of Galipea officinalis

• Hana Doušová,
• Radim Horák,
• Zdeňka Růžičková and
• Petr Šimůnek

Beilstein J. Org. Chem. 2015, 11, 884–892, doi:10.3762/bjoc.11.99

• be considered vinylogous amides. Hence, their nucleophilicity is lowered and enaminones can be more challenging substrates for C–N cross-coupling compared to ordinary enamines. We used 3a as the model substrate for the optimization study. The reaction conditions were surveyed from the following

Thiazole formation through a modified Gewald reaction

• Carl J. Mallia,
• Lukas Englert,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 875–883, doi:10.3762/bjoc.11.98

• aromatic appendage shows that an electron donating group (entries 4 and 5, Table 4) gives a better yield than an electron withdrawing group (entries 6 and 7, Table 4). This is presumably due to a subtle balance between the basicity and nucleophilicity of the intermediate anion, which could in the case of

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• of phenol, weakened the nucleophilicity for this type of reaction. Styrene (6) has an oxidation potential of 1.94 V (vs SCE) [22] and, hence, could also be oxidized by the chosen photocatalyst PDI. The corresponding photocatalytic nucleophilic additions to 6 (Table 1) yielded less of each product

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• of these Michael acceptors and the low inherent nucleophilicity of the metal alkynylides. In 2010, Shibasaki and co-workers developed the asymmetric 1,4-addition of terminal alkynes to α,β-unsaturated thioamides [192]. In order to achieve this reaction, Shibasaki and co-workers used a soft Lewis acid