β-Lactamase inhibition profile of new amidine-substituted diazabicyclooctanes

• Zafar Iqbal,
• Lijuan Zhai,
• Yuanyu Gao,
• Dong Tang,
• Xueqin Ma,
• Jinbo Ji,
• Jian Sun,
• Jingwen Ji,
• Yuanbai Liu,
• Rui Jiang,
• Yangxiu Mu,
• Lili He,
• Haikang Yang and
• Zhixiang Yang

Beilstein J. Org. Chem. 2021, 17, 711–718, doi:10.3762/bjoc.17.60

• -dimethylaminopyridine (DMAP) as the base. Then, the palladium-catalyzed hydrogenation of compounds B1–21 in THF or EtOAc led to the hydroxy derivatives C1–21. It has been observed that a catalytic amount of triethylamine (TEA) in EtOAc enhances the rate of the hydrogenolysis of benzyl ethers. Compounds C1–21 were then

Valorisation of plastic waste via metal-catalysed depolymerisation

• Francesca Liguori,
• Carmen Moreno-Marrodán and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• (a solvent is the reagent and solvolyses include hydrolysis, glycolysis, alcoholysis and aminolysis) and hydrogenolysis reactions (H2 as reagent). Hydrolysis (sometimes called hydrocracking) is in between thermochemical and chemolytic processing, basically consisting of depolymerisation by the

• conditions. For instance, for polyesters, alcoholysis may provide mixed monomers formally derived from transesterification reactions [89][90], while aminolysis provides amides and alcohols [91][92]. In the search of “greener” technologies for plastic recycling, catalytic hydrogenolysis processes have been

• ), bis(2-hydroxyethyl)terephthalate (BHET), terephthalamides (TPM [171]) and EG (Figure 3). Catalytic hydrogenolysis, hydrolysis, methanolysis and glycolysis reactions of (postconsumer) PET have been reviewed, each showing their own advantages and disadvantages [172][173]. For instance, glycolysis

Synthetic strategies of phosphonodepsipeptides

• Jiaxi Xu

Beilstein J. Org. Chem. 2021, 17, 461–484, doi:10.3762/bjoc.17.41

• 17 was synthesized via the coupling of methyl N-Cbz-1-aminoethylphosphonochloridate (13b) generated from phosphonic monomethyl ester 12b and methyl (S)-2-hydroxy-3-phenylpropanoate (18) followed by hydrogenolysis. It was further coupled to cyclen to afford various cyclen-containing

• methyl N-Cbz-protected 1-aminoethylphosphonochloridate 13b with methyl ᴅ-lactate (22a) and methyl mercaptoacetate (22b), respectively, followed by a basic hydrolysis and hydrogenolysis. The bioassay results indicated that the phosphonothiodepsidipeptide 20b did not inhibit VanX (Scheme 3) [21]. It was

• -aminoethylphosphonochloridate (13b) with different benzyl 1-hydroxyalkanoates 26 followed by hydrogenolysis and hydrolysis. The bioassay results indicated that six out of the seven synthetic phosphonodepsipeptides 25 inhibited VanX with IC50 values ranging from 0.48 to 8.21 mM (Scheme 4) [7]. Two optically active

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• hydrogenolysis of benzyl ethers (H2, Pd) [72], DIBAL-H reduction of esters to form alcohols [73], oxidative cleavage of vinyl groups to form carboxylic acids (KMnO4) [74], and the conversion of the acids into amines using the Curtius rearrangement (SOCl2, followed by Me3SiN3, thermolysis, and acid hydrolysis of

• -difluorocyclopropanes in the synthesis of fluoroalkenyl-substituted compounds (monofluoroalkenes) have been actively studied. Great opportunities exist for the use of transition metal catalysis. The catalytic hydrogenolysis of 1,1-difluoro-3-methyl-2-phenylcyclopropane (151) led to the regioselective C2–C3 distal bond

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• , it was transformed into (E)-vinylboronate (+)-145b in perfect stereoselectivity by using the recently developed boron-Wittig reaction with bis[(pinacolato)boryl]methane (144) [79]. By applying the Corey–Fuchs dibromoolefination and followed by Pd-catalyzed hydrogenolysis under Uenishi's conditions

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• subjected to simultaneous catalytic hydrogenation and hydrogenolysis of the protecting group Cbz to give (−)-adaline (1) in 90% yield. The asymmetric synthesis achieved by Liebeskind et al. presented a high enantiomeric excess and good yields. Also, the proposed route differed from the previously mentioned

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• formation of this side-product but did not lead to an overall increase in the yield of 11. Despite the modest optimised yield of the difluoroalkane 11, a sufficient quantity of this material was secured to continue with the synthesis. The hydrogenolysis of the benzyl ether of 11 provided the primary alcohol

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

• Tatsuya Kumon,
• Miroku Shimada,
• Jianyan Wu,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 2193–2200, doi:10.3762/bjoc.16.184

• -fluoroalkylated indenone 6 in 98% yield. Subsequently, a hydrogenolysis with 1 mol % of Pd/C under a hydrogen atmosphere in methanol at room temperature for 15 h produced the desired 2-fluoroalkylated indanone 7 as the trans-isomer in 69% yield [33][34][35]. The stereochemical assignment of 5aA and 7 was carried

Synthesis of monophosphorylated lipid A precursors using 2-naphthylmethyl ether as a protecting group

• Jundi Xue,
• Ziyi Han,
• Gen Li,
• Khalisha A. Emmanuel,
• Cynthia L. McManus,
• Qiang Sui,
• Dongmian Ge,
• Qi Gao and
• Li Cai

Beilstein J. Org. Chem. 2020, 16, 1955–1962, doi:10.3762/bjoc.16.162

• catalytic hydrogenolysis over Pd/C under 15 kg/cm2 of H2 to give the target lipid X monosaccharide 1 (as triethylammonium salt) in good yield. Having the glycosyl donor 20 and acceptor 18 at hand (Scheme 2), in order to prepare the disaccharide precursor, the glycosylation reaction was performed first

One-pot synthesis of isosorbide from cellulose or lignocellulosic biomass: a challenge?

• Isaline Bonnin,
• Raphaël Mereau,
• Thierry Tassaing and
• Karine De Oliveira Vigier

Beilstein J. Org. Chem. 2020, 16, 1713–1721, doi:10.3762/bjoc.16.143

• conversion of cellulose and even spruce in a one-step hydrogenolysis reactions to form C4 to C6 sugar alcohols [20]. For the C6 sugar alcohols including the isosorbide formation, the yield was below 6% whatever catalyst was used at 160 °C, under 50 bar of H2 in a 36 mL stainless steel autoclave equipped with

• experiments were made in a batch reactor containing 500 mg of α-cellulose, 100 mg of 5 wt % Ru/C catalyst and 10 mL of water with an acid concentration from 3.47 to 55.1 mmol·L−1 at 160 °C under 50 bar of H2 (25 °C). It was reported that the rate of cellulose hydrogenolysis reaction depends on the acid

• g of 4 wt % Ru/C, 3 g of Amberlyst 70, isosorbide yield of 56% at 180 °C under 50 bar of H2 after 16 h of reaction. A comparison between these results and sequential reactions leading in the first step (hydrogenolysis of cellulose) to 51% of sorbitol and in the second step (dehydration of sorbitol

Synthesis of 3-substituted isoxazolidin-4-ols using hydroboration–oxidation reactions of 4,5-unsubstituted 2,3-dihydroisoxazoles

• Lívia Dikošová,
• Júlia Laceková,
• Ondrej Záborský and
• Róbert Fischer

Beilstein J. Org. Chem. 2020, 16, 1313–1319, doi:10.3762/bjoc.16.112

• (Scheme 4). According to the literature, the N-debenzylation by a Pd-catalyzed hydrogenolysis in methanol with formic acid as the hydrogen source [37][38] should allow the access to N-deprotected isoxazolidines. Unfortunately, all attempts to remove the benzyl group directly from the model isoxazolidine

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• high diastereoisomeric purity (Scheme 36). The subsequent deprotection of 151 had to be achieved with BrO3−, because hydrogenolysis resulted in defluorination [74]. Alternatively, a series of substituted anti-β-fluorophenylalanine derivatives 154a–d was obtained from the corresponding enantiopure α

Efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates

• Marcin Kaźmierczak and
• Henryk Koroniak

Beilstein J. Org. Chem. 2020, 16, 756–762, doi:10.3762/bjoc.16.69

• into the salts 14 was applied. The salts 14 could be then crystallized and subjected to X-ray studies. A standard N−debenzylation protocol was employed to remove the benzyl protecting group. The hydrogenolysis reaction was catalyzed by palladium on carbon (Pd/C), and was carried out in trifluoroethanol

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

• Zhenghui Liu,
• Peng Wang,
• Zhenzhong Yan,
• Suqing Chen,
• Dongkun Yu,
• Xinhui Zhao and
• Tiancheng Mu

Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61

• reacts with PPh3 to form RhCl(PPh3)3, which is able to activate C–I bonds in aryl iodides realizing the insertion of CO and hydrogenolysis with H2. The final trapping of HI by the base Et3N regenerates the catalyst to complete the reaction cycle. As far as we know, this is the first time that

Convenient synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-antigen of Escherichia albertii O4

• Tapasi Manna,
• Arin Gucchait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2020, 16, 106–110, doi:10.3762/bjoc.16.12

• ) hydrogenolysis of benzyl ethers and benzylidene acetals over Pearlman’s catalyst [36] to furnish the desired pentasaccharide 1 in 49% overall yield (Scheme 4). The structure of compound 1 was unambiguously characterized by its NMR spectral analysis [signals at δ 5.37 (d, J = 2.0 Hz, H-1A), 5.29 (d, J = 3.5 Hz, H

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• lactone with the lithium salt of dimethyl methylphosphonate followed by an elimination step of the resulting hemiketal, leading to the corresponding exo- and endo-glycal derivatives. The ensuing selective monodemethylation and hydrogenolysis of the benzyl groups and reduction of the 4-azido group gave the

Automated glycan assembly of arabinomannan oligosaccharides from Mycobacterium tuberculosis

• Alonso Pardo-Vargas,
• Priya Bharate,
• Martina Delbianco and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2019, 15, 2936–2940, doi:10.3762/bjoc.15.288

• methanolysis, followed by Pd/C-catalyzed hydrogenolysis of the carboxybenzyl group and the benzyl ethers. Mannosides 4–6 were deprotected and purified using reversed-phase HPLC to obtain fully deprotected mannosides 10–12 (Figure 2). For the arabinomannosides 7–9, the acid-labile arabinose chain was cleaved

• during hydrogenation, giving a complex mixture of deletion sequences lacking one to six arabinose moieties. To overcome this challenge, hydrogenolysis with Pd(OH)2 was performed to access the fully deprotected arabinomannosides 13–15 (Figure 2). Conclusion A collection of AM oligosaccharides containing α

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• alkylation, reduction and catalytic hydrogenolysis, (+)-199 was converted to desired product (−)-200 with 80% ee (Scheme 62). An electrochemical method for the asymmetric oxidative dimerization of cinnamic acid derivatives was developed by Watanabe in 2016 [109]. The substrates for the electrochemical

Chemical synthesis of the pentasaccharide repeating unit of the O-specific polysaccharide from Escherichia coli O132 in the form of its 2-aminoethyl glycoside

• Debasish Pal and
• Balaram Mukhopadhyay

Beilstein J. Org. Chem. 2019, 15, 2563–2568, doi:10.3762/bjoc.15.249

• -acetylation using NaOMe in MeOH followed by hydrogenolysis in a ThalesNano continuous flow hydrogenation assembly using a 10% Pd-C cartridge [29]. After three cycles of hydrogenation, formation of the target pentasaccharide 1 was evident from the mass spectrum (Scheme 4). Conclusion In conclusion, the

A review of the total syntheses of triptolide

• Xiang Zhang,
• Zaozao Xiao and
• Hongtao Xu

Beilstein J. Org. Chem. 2019, 15, 1984–1995, doi:10.3762/bjoc.15.194

• corresponding carboxylic acid followed by hydrogenolysis with H2/Pd-C led in spontaneous lactonization to give the key butenolide 66. Oxidation of 66 with CrO3/AcOH–H2O, followed by saponification and reduction afforded known benzyl alcohol 46 (19% from 66). Then, phenol 46 was converted to the corresponding

Application of chiral 2-isoxazoline for the synthesis of syn-1,3-diol analogs

• Juanjuan Feng,
• Tianyu Li,
• Jiaxin Zhang and
• Peng Jiao

Beilstein J. Org. Chem. 2019, 15, 1840–1847, doi:10.3762/bjoc.15.179

• oxidation conditions. Based on this assumption, the corresponding silyl nitronate from 3-nitropropanal or its acetal were not tried for cycloaddition. We then set to liberate the β-hydroxy ketone synthon by ring opening of the isoxazoline 3 (Scheme 3). Raney-Ni-catalyzed hydrogenolysis in the presence of

• of the desired β-hydroxy ketone was observed. In our experience, the hydrogenolysis of a 2-isoxazoline having a 5-ester group was troublesome. Thus, the 5-ester group was reduced with NaBH4 to give 5. The hydroxy group was subsequently protected with benzoyl (Scheme 3), which also worked as a

• exemplified in Scheme 2. These results prompted us to try the oxidation in a later stage. When 6 was subjected to Raney-Ni-catalyzed hydrogenolysis, the desired β-hydroxy ketone 7 was obtained in 85% yield (Scheme 3). Under the weakly acidic conditions, the THP group survived. Next, a Narasaka–Prasad

Design, synthesis and biological evaluation of immunostimulating mannosylated desmuramyl peptides

• Rosana Ribić,
• Ranko Stojković,
• Lidija Milković,
• Mariastefania Antica,
• Marko Cigler and
• Srđanka Tomić

Beilstein J. Org. Chem. 2019, 15, 1805–1814, doi:10.3762/bjoc.15.174

• condensation reactions with hydroxyisobutyryl and glycolyl mannosides. The synthesis of desmuramyl peptide 7 with an adamantane moiety bound at C-terminus is presented in Scheme 2. After hydrogenolysis of the starting dipeptide, condensation of free carboxyl group with adamant-1-ylamine hydrochloride was

N-(1-Phenylethyl)aziridine-2-carboxylate esters in the synthesis of biologically relevant compounds

• Iwona E. Głowacka,
• Aleksandra Trocha,
• Andrzej E. Wróblewski and
• Dorota G. Piotrowska

Beilstein J. Org. Chem. 2019, 15, 1722–1757, doi:10.3762/bjoc.15.168

• compounds were obtained in a 84:16 ratio. The major ether (2R,1'R)-26, which emerged from the displacement of the tosyloxy group (path a), was accompanied by (2S,1'R)-26 which came from the aziridine ring opening at C3 (path b). After chromatographic purification and hydrogenolysis enantiomerically pure (R

• was followed by the aziridinium ion opening with cyanide to access compound 64 which was first transformed into diester and later after hydrogenolysis into the γ-lactam (S)-65 [62]. The methoxycarbonyl to acetyl group conversion was accomplished via Weinreb amide to give the pyrrolidin-2-one (S)-66

• readily accomplished [78] from the aziridine alcohol (2R,1'R,1''S)-28 available by addition of phenyllithium to the aldehyde (2R,1'S)-6 [30]. Opening of the aziridine ring in (2R,1'R,1''S)-28 with acetic acid yielded the acetate (1R,2R,1'S)-106 while catalytic hydrogenolysis led to the formation of (1R,2R

An azobenzene container showing a definite folding – synthesis and structural investigation

• Abdulselam Adam,
• Saber Mehrparvar and
• Gebhard Haberhauer

Beilstein J. Org. Chem. 2019, 15, 1534–1544, doi:10.3762/bjoc.15.156

• protective group, the resulting amino acid was cyclodimerized to the benzyl-protected macrocycle. The yield for the cyclization amounts to about 50%. The last step was the removal of the benzyl group by hydrogenolysis to yield the desired macrocycle 3a. The cyclopeptide 2a [52] is commercially available

Anomeric sugar boronic acid analogues as potential agents for boron neutron capture therapy

• Daniela Imperio,
• Erika Del Grosso,
• Silvia Fallarini,
• Grazia Lombardi and
• Luigi Panza

Beilstein J. Org. Chem. 2019, 15, 1355–1359, doi:10.3762/bjoc.15.135

• pseudoaxial substituents. The alternative, a more stable transition state formed from the re-face attack would bear to the actually obtained 3S configurated boronic acid analogue 7. The final deprotection of compound 7 by conventional catalytic hydrogenolysis gave the final compound 8 in almost quantitative

• [19], again with 5 equiv of reagent, afforded the cyclic boronic acid 10 in a fair yield. Benzylidene group hydrogenolysis gave the deprotected pure cyclic boronic acid 11 in quantitative yield and compound 11 proved to be stable for months. In this case the elimination reaction was not observed as