Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• ]. The 2-aminopyridine-1-oxide directing group was used in a rare example of a cobalt-catalyzed oxidative alkoxylation of arenes 66 and alkenes 67 to afford products 68 and 69 under mild contitions [69] (Scheme 14). The directing group can be removed to obtain the corresponding benzoic acid 71 from the

Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

• Markus Nörrlinger and
• Thomas Ziegler

Beilstein J. Org. Chem. 2014, 10, 2453–2460, doi:10.3762/bjoc.10.256

• as follows (Table 2). Both Fmoc-protected benzoic acid derivatives 7 and 9 (Scheme 1) were each condensed with each of the four malonylamidoglycosides 12a–d (Table 1) to afford eight intermediate tert-butyl esters 13 and 14 in 45–67% yield. For the condensation step between 7 and 9 with 12

• (Scheme 2). Treatment of 6 and 8 with a 2:1 mixture of formic acid and dichloromethane at room temperature for 38 h, as described for the preparation of building blocks 1 and 2 (see Table 2), afforded the benzoic acid derivatives 15 and 18 in 93% yield for each. Likewise, treatment of 5 and 8 with 20

• usefulness for the preparation of corresponding glycosylated or non-glycosylated dipeptides. The benzoic acid derived building blocks described here will be used in combination with previously described similar glycopeptoids based on asparaginic acid or PNA-like backbones for automated SPOT syntheses of

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• could be reduced again and defunctionalized materials were isolated in moderate to good yields (Table 3, entries 10 and 11). Bis(trifluoromethyl)benzoic acid 5 could easily be recovered (>90%) in an acid–base extraction step. Also bis(trifluoromethyl)benzoates of non-benzylic α-cyanohydrin 6a and α

• photochemical deoxygenation, 3,5-bis(trifluoromethyl)benzoic acid (5) is formed, which can be easily recovered in high yield and from which anhydride 9 can be regenerated as described above. Attempts to deoxygenate simple alkyl-substituted alcohols (primary, secondary and tertiary) were not successful; for

• (trifluoromethyl)benzoic acid can be recycled and reactivated under redox neutral conditions, and moreover, the in situ activation of alcohols with this auxiliary is possible we envision that an overall continuous process could be developed for the deoxygenation of alcohols by this protocol. That ultimately only

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• irradiation conditions with the substrates adsorbed onto Montmorillonite K-10 clay (Scheme 45) [122]. The formation of compounds 110 proceeded via: (a) N-acylation of aminosugar by the anthranilic acid derivative, and (b) N-acylation of the resulting amide at the aromatic amino group by benzoic acid (or 4

Olefin cross metathesis based de novo synthesis of a partially protected L-amicetose and a fully protected L-cinerulose derivative

• Bernd Schmidt and
• Sylvia Hauke

Beilstein J. Org. Chem. 2014, 10, 1023–1031, doi:10.3762/bjoc.10.102

• benzoylation in pyridine resulted exclusively in the formation of furan 10 (Table 2, entry 1). We reasoned that pyridine initiates an E/Z-isomerization of the enal through nucleophilic attack at the β-position, followed by lactol formation, benzoylation of the lactol and finally elimination of benzoic acid

• eventually obtained in high yields from benzoic acid using Steglich’s esterification [61] (Table 2, entry 3). With enal 9 in hands, selective hydrogenation of the C–C double bond had to be accomplished in the next step. Lipshutz’ modification [62] of Stryker’s reagent [63], which we had previously used

Staudinger ligation towards cyclodextrin dimers in aqueous/organic media. Synthesis, conformations and guest-encapsulation ability

• Malamatenia D. Manouilidou,
• Yannis G. Lazarou,
• Irene M. Mavridis and
• Konstantina Yannakopoulou

Beilstein J. Org. Chem. 2014, 10, 774–783, doi:10.3762/bjoc.10.73

• its X-ray structure solved in the case of reaction between benzyl azide and 2-(diphenylphosphanyl)benzoic acid methyl ester [7]. The advantages of the Staudinger ligation and its “traceless” variant [6][8] are the employment of the azido group, a moiety orthogonal to naturally existing functional

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

• that the lower electrophilicity of arylimines and the possible enamide conjugation could account for this. Furthermore, it was shown that the pKa of the carboxylic acid significantly influenced the reaction rates, in which TFA gave the best results (2 days vs. 5 days for benzoic acid). No

• orthogonally protected carbohydrate-derived azido-acetal and trimethylphosphine yielded the necessary cyclic imine, which then was exposed to benzoic acid and different isocyanides. The resulting Ugi-bisamides 163 were obtained in moderate to good yields (22–78%), in which the more sterically demanding

Preparation of new alkyne-modified ansamitocins by mutasynthesis

• Kirsten Harmrolfs,
• Lena Mancuso,
• Binia Drung,
• Florenz Sasse and
• Andreas Kirschning

Beilstein J. Org. Chem. 2014, 10, 535–543, doi:10.3762/bjoc.10.49

• polyketide synthase in A. pretiosum and thus no formation of new ansamitocin derivatives was encountered in these cases. In contrast, benzoic acid 11 provided Br-F-ansamitocin derivatives 21a–d after being fed to a growing culture of the mutant strain as judged by HRMS (Scheme 4). The retention times in LC

• )benzoic acid 12 to cultures of the AHBA(−)-mutant of A. pretiosum yielded six new alkynyl-modified ansamitocin derivatives 23a–f in yields in the lower mg/L range (Scheme 6). Among them, the major compound 23f was obtained in 0.34% yield based on compound 12, furnishing enough mutasynthetic material (15

• MS spectra. Derivatives 23a, 23b, 23d, 23e and 24a, 24e were detected only by HRMS–MS analysis of the crude extract. Mutasynthetic experiments with vinyl(amino)benzoic acid 15 supposedly provided ansamitocin derivative 25 as judged by HRMS–MS analysis of the crude extract (Scheme 7). However, yields

Continuous flow nitration in miniaturized devices

• Amol A. Kulkarni

Beilstein J. Org. Chem. 2014, 10, 405–424, doi:10.3762/bjoc.10.38

• , nitric acid and acetic anhydride, which led to a homogeneous system. However, an over-oxidation of 16 was encountered due to the presence of acetic anhydride, so that benzoic acid was formed. The poor solubility of benzoic acid in the aqueous phase led to an immediate clogging of the tubular reactor

• handling of the solubility of the undesired solid has to be considered as well. This issue was finally dealt with by dissolving the benzoic acid in a suitable solvent (n-hexane), which also reduced the reaction time to a few seconds. However, even though the conversion of benzaldehyde was complete, the

Additive-assisted regioselective 1,3-dipolar cycloaddition of azomethine ylides with benzylideneacetone

• Chuqin Peng,
• Jiwei Ren,
• Jun-An Xiao,
• Honggang Zhang,
• Hua Yang and
• Yiming Luo

Beilstein J. Org. Chem. 2014, 10, 352–360, doi:10.3762/bjoc.10.33

• formed as indicated by TLC, and cyclization was not observed with 2.0 equiv p-TSA and TFA (Table 2, entry 8 and entry 9). Both the benzoic acid and acetic acid slightly improved the formation of regioisomer 5a (Table 2, entry 10 and entry 11). Additionally, a cycloaddition product was not observed with

Substrate dependent reaction channels of the Wolff–Kishner reduction reaction: A theoretical study

• Shinichi Yamabe,
• Guixiang Zeng,
• Wei Guan and
• Shigeyoshi Sakaki

Beilstein J. Org. Chem. 2014, 10, 259–270, doi:10.3762/bjoc.10.21

• CT complex may be supported by two hydrogen-bond networks. The CT complex is probable even by protic solvents as shown in Scheme 5. The CT complex assisted by hydrogen bonds was also obtained in the benzoic acid–ethylamine system by our recent study [37]. In (iii) of Figure 1, a proton transfer TS1

Organobase-catalyzed three-component reactions for the synthesis of 4H-2-aminopyrans, condensed pyrans and polysubstituted benzenes

• Moustafa Sherief Moustafa,
• Saleh Mohammed Al-Mousawi,
• Maghraby Ali Selim,
• Ahmed Mohamed Mosallam and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2014, 10, 141–149, doi:10.3762/bjoc.10.11

• crystallographic methods (Figure 4). An attempt to prepare the bicyclic 2-amino-4H-pyran 24 by the reaction of dione 14 with ethyl propiolate (4a) in the presence of malononitrile and L-proline or DABCO was not successful. Instead, these substances reacted to the fused benzoic acid ester 26, which was

• produce zwitterion 35a. Reaction of 35a or its protonated form with malononitrile, which is likely generated by hydrolysis of 7a, then forms 36a that cyclizes and aromatizes by loss of HCN to yield 37a. This sequence is closely related to the one described above for the formation of benzoic acid

Bis(benzylamine) monomers: One-pot preparation and application in dendrimer scaffolds for removing pyrene from aqueous environments

• Olivia N. Monaco,
• Sarah C. Tomas,
• Meghan K. Kirrane and
• Amy M. Balija

Beilstein J. Org. Chem. 2013, 9, 2320–2327, doi:10.3762/bjoc.9.266

• solution. Results and Discussion Condensation of 3,5-diamino benzoic acid (1) with 2.5 equiv of benzaldehyde (2a) in methanol at room temperature resulted in the precipitation of bisimine monomer 3a, which was isolated cleanly by filtration after 20 minutes [11][12]. Electron-deficient, electron-rich, and

• temperatures hindered the ability to cleanly obtain bisimines 3. Alternatively, the condensation of 3,5-diamino benzoic acid with 2.1 equiv of benzaldehyde (2a) in methanol at room temperature followed by in-situ reduction with NaBH4 and acidification with 2 N HCl resulted in the precipitation of bisamine 4a

Synthesis of enantiomerically pure N-(2,3-dihydroxypropyl)arylamides via oxidative esterification

• Akula Raghunadh,
• Satish S More,
• T. Krishna Chaitanya,
• Yadla Sateesh Kumar,
• Suresh Babu Meruva,
• L. Vaikunta Rao and
• U. K. Syam Kumar

Beilstein J. Org. Chem. 2013, 9, 2129–2136, doi:10.3762/bjoc.9.250

• , reacts with dioxygen to form the peroxy-species, which afforded the corresponding hydroxypropyl benzoate. A similar kind of mechanism was also proposed by Ding et al. [40]. To study the mechanism, we conducted a reaction with benzoic acid as a substrate under optimized conditions with or without NHC

Post-Ugi gold-catalyzed diastereoselective domino cyclization for the synthesis of diversely substituted spiroindolines

• Amit Kumar,
• Dipak D. Vachhani,
• Sachin G. Modha,
• Sunil K. Sharma,
• Virinder S. Parmar and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2013, 9, 2097–2102, doi:10.3762/bjoc.9.246

• the synthesis of spiroindolines with propargylamines as an alkyne source (Scheme 1). Results and Discussion The use of benzoic acid as an acid component in the Ugi-4CR did not produce the Ugi-adduct in good yield even after a prolonged reaction time. Therefore, we switched to phenylacetic acid. The

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• benzyl alcohol oxidation [27], the esterification of benzoic acid in a microwave tubular flow reactor [28], a continuous flow recycle microwave reactor for homogeneous and heterogeneous processes [29], a mesoscale flow reactor utilizing Fe3O4 as a microwave absorbing packed reactor bed with internal

Damage of polyesters by the atmospheric free radical oxidant NO₃^•: a product study involving model systems

• Catrin Goeschen and
• Uta Wille

Beilstein J. Org. Chem. 2013, 9, 1907–1916, doi:10.3762/bjoc.9.225

• aromatic system. Conclusion We have shown for the first time that certain aromatic moieties in commercial polyesters (e.g. alkylated benzoic acid derivatives of type 3) are vulnerable to damage by the environmental free-radical oxidant NO3•. The reaction is most likely initiated by ET to give a highly

Bioinspired total synthesis of katsumadain A by organocatalytic enantioselective 1,4-conjugate addition

• Yongguang Wang,
• Ruiyang Bao,
• Shengdian Huang and
• Yefeng Tang

Beilstein J. Org. Chem. 2013, 9, 1601–1606, doi:10.3762/bjoc.9.182

• stirring a mixture of 3 and 7 in DCM at room temperature for 12 h in the presence of Hayashi catalyst B [28]. It was found that the desired product 5a was obtained, albeit in moderate yield and enantioselectivity (Table 1, entry 1). To our delight, the usage of benzoic acid (BA) as an additive could

Synthesis and spectroscopic properties of 4-amino-1,8-naphthalimide derivatives involving the carboxylic group: a new molecular probe for ZnO nanoparticles with unusual fluorescence features

• Laura Bekere,
• David Gachet,
• Vladimir Lokshin,
• Wladimir Marine and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2013, 9, 1311–1318, doi:10.3762/bjoc.9.147

• (3H)-yl)benzoic acid (4) was found to be a sensitive molecular probe for ZnO nanoparticles. We investigated in detail one- and two-photon absorption properties of this fluorophore. In nonpolar solvents, the acid 4 absorbs at about 400 nm and fluoresces at 500 nm with a fluorescence lifetime of about 7

• involve the benzoic acid moiety at the N-atom of the 1,8-naphthalimide. At first we used a general straightforward method involving the hydrolysis of the chloro substituted imide 1 and eventual substitution of the chlorine atom by piperidine. (Scheme 1, Pathway A). The pathway A has two major

• , 65.67; H, 3.31; N, 3.83; found: C, 65.30; H, 3.24; N, 3.79. 4-(6-Chloro-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)benzoic acid (2): Derivative 1 (1.0 mmol, 0.36 g) was suspended in water (5 mL) and a solution of sodium hydroxide (1.3 mmol, 0.05 g) in water (5 mL) was added at room temperature. The

NHC-catalysed highly selective aerobic oxidation of nonactivated aldehydes

• Lennart Möhlmann,
• Stefan Ludwig and
• Siegfried Blechert

Beilstein J. Org. Chem. 2013, 9, 602–607, doi:10.3762/bjoc.9.65

• described by Yoshida et al. [26]. With electron-deficient arylaldehydes the yields are good to moderate. However, benzaldehyde itself gave less than 10% product. Under our conditions using 2 mol % D and 2 equiv H2O we obtained benzoic acid with a yield of 97%. Encouraged by this result, we carried out

A new family of four-ring bent-core nematic liquid crystals with highly polar transverse and end groups

• Kalpana Upadhyaya,
• Venkatesh Gude,
• Golam Mohiuddin and
• Rao V. S. Nandiraju

Beilstein J. Org. Chem. 2013, 9, 26–35, doi:10.3762/bjoc.9.4

• molecules overlap. This contributes to the strong attractive interaction between them. The molecule consists of two linkages between the three aromatic fragments, giving an ortho-hydroxy benzylidene moiety, a benzoic acid ester moiety, and a biphenyl residue. The salicylidene linkage instead of the

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• (Scheme 22) [43]. Their strategy involved the reaction of salicylaldehyde (5) and unsaturated aldehyde 60 in the presence of catalytic amounts of TES-protected prolinol 64 and benzoic acid. High yields (87%) and excellent enantioselectivity (88%) of 2-phenylchromene 62 were achieved when the reaction was

• performed in 1,2-dichloroethane as the solvent. The presence of the benzoic acid additive is thought to be responsible for the increase in the enantioselectivity and higher yields of this reaction when compared to that of Govender and co-workers. It is also instructive to note that the catalyst loading for

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

• observed. The ball-milling approach was applied to the (S)-BINAM-L-prolinamide (II) catalysed direct aldol reaction between ketones and aldehydes under solvent-free conditions by Najera and co-workers (Scheme 3) [33][34]. Using 5–10 mol % of II and 10–20 mol % of benzoic acid as additive, the aldol

Acylsulfonamide safety-catch linker: promise and limitations for solid–phase oligosaccharide synthesis

• Jian Yin,
• Steffen Eller,
• Mayeul Collot and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 2067–2071, doi:10.3762/bjoc.8.232

• was created with TentaGel resin [15][16], which swells in water, because encouraging results have been achieved previously with this resin. 4-(Chloromethyl)benzoic acid (13) served as an additional spacer [25] between 10 and TentaGel amino resin to incorporate the Zemplén cleavage site. Treatment of

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• includes the selective reduction of nitro groups to amines in the presence of ketones (Scheme 11) [50][51], and the oxidation of benzaldehyde to benzoic acid, albeit with incredibly poor conversion [52]. The conversion of L-lysine (32) to L-pipecolinic acid (33, Scheme 12) has also been investigated by