Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• -trimethyltriphenylene (6) in 46% yield. Later on, they first directly tried to convert compound 6 into the expected sumanene (2) by using a cyclodehydrogenation reaction in the presence of Pd/C at 400 °C, surprisingly they obtained only mono-bridged compound 7 in around 70% yield along with some of an unidentified

• reaction followed by the reduction of the nitro functionality into the amine group and subsequently performing a Sandmeyer reaction as shown in Scheme 20 [14]. Additionally, they have reported the hydrogenation of sumanene to generate compound 89 having one benzene ring intact in the framework using Pd/C

• -selective cation–π interaction (Scheme 27) [60]. In this study, they used already discussed formylsumanene 66 and aminosumanene 114 prepared from nitrosumanene through the reduction of 80 with Pd/C/H2. As can be seen from Scheme 27, these attractive building blocks 66 and 114 were then converted into the

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

Convenient access to pyrrolidin-3-ylphosphonic acids and tetrahydro-2H-pyran-3-ylphosphonates with multiple contiguous stereocenters from nonracemic adducts of a Ni(II)-catalyzed Michael reaction

• Alexander N. Reznikov,
• Dmitry S. Nikerov,
• Anastasiya E. Sibiryakova,
• Victor B. Rybakov,
• Evgeniy V. Golovin and
• Yuri N. Klimochkin

Beilstein J. Org. Chem. 2020, 16, 2073–2079, doi:10.3762/bjoc.16.174

• . Hydrogenation in the presence of Raney nickel or Pd/C in various solvents leads to a mixture of products, among which 8 and 9 are identified (Scheme 1). A satisfactory yield of the desired product 7 (78% by 31P NMR of reaction mixture) was achieved when the hydrogenation was carried out in acetic acid in the

• presence of Pd/C. However, phosphonate 7 was unstable: already during its isolation, it was partially transformed into compounds 8 and 9. It can be assumed that N-alkylation by the phosphoryl group occurs [47][48][49]. To avoid this undesirable process, the product 7 was formylated before its isolation

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

• 7, EDC·HCl, DMAP, CH2Cl2, rt, 67.5% (2 steps); (c) HF/Py, THF, −40 °C to rt, 78%; (d) tetrabenzyl pyrophosphate, LHMDS, THF, −78 °C, 91%; (e) H2 (15 kg/cm2), Pd/C, THF/H2O, 38 °C, 86%. Synthesis of the disaccharide lipid A precursor 2. Conditions: (a) TfOH, 4 Å MS, dry CH2Cl2, 94%; (b) Zn, AcOH

Synthesis, docking study and biological evaluation of ᴅ-fructofuranosyl and ᴅ-tagatofuranosyl sulfones as potential inhibitors of the mycobacterial galactan synthesis targeting the galactofuranosyltransferase GlfT2

• Marek Baráth,
• Jana Jakubčinová,
• Zuzana Konyariková,
• Stanislav Kozmon,
• Katarína Mikušová and
• Maroš Bella

Beilstein J. Org. Chem. 2020, 16, 1853–1862, doi:10.3762/bjoc.16.152

• by GlfT2. Reagents and conditions: a) 1. (BnO)2P-NMe2, 1H-tetrazole, 0 °C→rt, 1 h, 2. m-CPBA, 0 °C→rt, 1.5‒2 h; b) H2, 10% Pd/C, MeOH, rt, 3‒4 h. Reagents and conditions: a) PivCl, pyridine, CH2Cl2, rt, overnight; b) BnBr, NaOH, TBAB, THF, reflux, 3 h. Reagents and conditions: a) EtSH, BF3∙OEt2

• , CH2Cl2, 0 °C, 2 h; b) 1. (BnO)2P-NMe2, 1H-tetrazole, 0 °C→rt, 1 h, 2. m-CPBA, 0 °C→rt, 1.5‒2 h; c) MeONa, MeOH, rt, 1.5 h; d) H2, 10% Pd/C, MeOH, rt, 3‒4 h; e) 3 M HCl, THF, 40 °C, 8 h. Reagents and conditions: a) PhSH, or iPrSH, BF3·OEt2, CH2Cl2, −5 °C, 1 h; b) BF3·OEt2, Ac2O, 0 °C, 1.5 h; c) PhSH, BF3

• ·OEt2, CHCl3, −20 °C, 1.5 h. Reagents and conditions: a) 1. (BnO)2P-NMe2, 1H-tetrazole, 0 °C→rt, 1 h, 2. m-CPBA, 0 °C→rt, 1.5‒2 h; b) H2, 10% Pd/C, MeOH, rt, 3‒4 h; c) 3 M HCl, THF, 40 °C, 8 h. Observed docking score and predicted Ki values of the docked compounds 1‒3. Evaluation of the effects of

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

• Teflon inserts for a reaction time between 1 h to 5 h. Another study was performed using sulfuric or hydrochloric acid in the presence of Pt/C, Pd/C or Ru/C catalysts [21]. In the presence of Pt/C and Pd/C associated to HCl or H2SO4 the isosorbide yield was very low (below 4%) for a total conversion of

• yield (50% under optimized conditions, 220 °C under 40 bar of H2 for 2 h and 0.5 M H2SO4 (aq) 30 mL, 40 mg of Ru/C (5 wt % of Ru) in a glass insert in an autoclave) than Pt/C, Pd/C and Rh/C catalysts for the one-pot one step conversion of BP to isosorbide. The nature of the acids to catalyze the

Synthesis of Streptococcus pneumoniae serotype 9V oligosaccharide antigens

• Sharavathi G. Parameswarappa,
• Claney L. Pereira and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2020, 16, 1693–1699, doi:10.3762/bjoc.16.140

• removal of all methyl and benzoate esters under basic conditions to obtain the partially protected pentasaccharide 32 that was hydrogenated using Pd/C and hydrogen to afford pentasaccharide 4 without the acetate group at the C-6 position of the mannosamine. Pentasaccharide 5, containing a C-6 O-acetate on

• mannosamine was obtained from 33, that in turn was a product of the benzylation of 32. Cleavage of the benzylidene group in 33 yielded 34 that was selectively acetylated at the primary alcohol at low temperature to obtain 35 [30]. The subsequent removal of the benzyl groups using hydrogenation with Pd/C in an

In silico rationalisation of selectivity and reactivity in Pd-catalysed C–H activation reactions

• Liwei Cao,
• Mikhail Kabeshov,
• Steven V. Ley and
• Alexei A. Lapkin

Beilstein J. Org. Chem. 2020, 16, 1465–1475, doi:10.3762/bjoc.16.122

• initial guess due to particularly bad initial geometry – discard the conformer/intermediate, (iv) decomposed intermediate (no Pd–C bond determined by interatomic distance analysis) – discard intermediate. Literature validation In order to test the developed algorithm, a representative literature data

• manually examined to ensure they represent the intermediates according to the particular mechanism. In particular, the bond length between the palladium atom and the corresponding carbon atom was given a maximum value of 2.4 Å to filter out inappropriate intermediates where there is no stable Pd–C bond [40

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

• Carlos H. Escalante,
• Eder I. Martínez-Mora,
• Carlos Espinoza-Hicks,
• Alejandro A. Camacho-Dávila,
• Fernando R. Ramos-Morales,
• Francisco Delgado and
• Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

• using manganese oxide or DDQ as the oxidizing reagents, or even including Pd/C at high temperatures (250 °C) [45], failed to obtain the series of indoles 23. It is likely that the electron withdrawing effect of the formyl group at the C-7 position counterbalance the delocalization direction of the

Synthesis of esters of diaminotruxillic bis-amino acids by Pd-mediated photocycloaddition of analogs of the Kaede protein chromophore

• Esteban P. Urriolabeitia,
• Pablo Sánchez,
• Alexandra Pop,
• Cristian Silvestru,
• Eduardo Laga,
• Ana I. Jiménez and
• Carlos Cativiela

Beilstein J. Org. Chem. 2020, 16, 1111–1123, doi:10.3762/bjoc.16.98

• Figure 5, provides additional information. Complex 4a has a dinuclear structure in which each Pd atom is surrounded by one C,N-ortho-metallated oxazolone and two oxygen atoms of the trifluoroacetate ligands, which act as bridging ligands between the two Pd(C^N) fragments. In turn, the two Pd(C^N

• necessary in order to obtain a clean release of the truxillic esters. In addition to the methoxycarbonylation of the Pd–C, the reaction also involves ring opening of the oxazolone moiety to afford the corresponding ester and amido groups. This ring opening was also observed in the case of the hydrogenation

• -diaminotruxillic bis-amino acids. The reaction of the cyclobutanes 4 with CO (1 atm) in MeOH/NCMe results in the ring opening of the oxazolone group, methoxycarbonylation of the Pd–C bonds, reductive elimination, and finally release of the 1,3-diaminotruxillic bis-amino esters 5 as single isomers (ε-isomer). The

Palladium-catalyzed regio- and stereoselective synthesis of aryl and 3-indolyl-substituted 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones

• Valeria Nori,
• Antonio Arcadi,
• Armando Carlone,
• Fabio Marinelli and
• Marco Chiarini

Beilstein J. Org. Chem. 2020, 16, 1084–1091, doi:10.3762/bjoc.16.95

• catalytic system showed that the ligand-free PdCl2 was the most effective catalyst (Table 1, entry 14). Other catalysts such as Pd(PPh3)4, Pd/C or Pd(OAc)2 provided inferior results (Table 1, entries 11–13). We then examined the reaction of 2a with 1.5 equiv of a variety of arylboronic acids. Using the

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

• acetate 60:40, v/v). The NMR spectroscopic data for fluorides 11 were in good agreement with our previous research [31]. Procedure for the synthesis of amines 13 The amines 13 were prepared in a similar manner as described in [35]. Fluoride 11 (1 equiv) was dissolved in 5 mL of TFE and then 10% Pd/C (20

Starazo triple switches – synthesis of unsymmetrical 1,3,5-tris(arylazo)benzenes

• Andreas H. Heindl and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2020, 16, 22–31, doi:10.3762/bjoc.16.4

• (E)-N-(3-nitro-5-(phenyldiazenyl)phenyl)acetamide (8), the reduction of the nitro group was attempted. However, the literature-known procedure of using sodium hydrosulfide did not yield the desired (E)-N-(3-amino-5-(phenyldiazenyl)phenyl)acetamide (9). Alternative reduction attempts, such as using Pd

• /C-catalyzed reduction by H2 in different solvents, SnCl2, or iron under acidic conditions were not successful either. In all cases, the reactions produced complicated mixtures, and the target compound could neither be identified nor isolated. At this stage, the second strategy via Pd-catalyzed

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

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

• David C. B. Siebert,
• Roman Sommer,
• Domen Pogorevc,
• Michael Hoffmann,
• Silke C. Wenzel,
• Rolf Müller and
• Alexander Titz

Beilstein J. Org. Chem. 2019, 15, 2922–2929, doi:10.3762/bjoc.15.286

• , THF, −20 °C (for 20a, 20b, 30a); (c) PyBOP, DIPEA, CH2Cl2, 0 °C (for 20c, 20d, 30b); (d) 4 M HCl/dioxane, rt; (e) NaOH, dioxane, 0 °C; (f) KOH, H2O, 0 °C to rt; (g) (for 26a) HSCH2CH2NHAc (HSNAc), IBCF, NMM, THF, −20 °C; (for 26b–d, 35a,b) HSNAc, TFFH, DIPEA, CH2Cl2, 0 °C; (h) Pd/C, H2, MeOH, rt; (i

• ) EDC, CuCl, CH2Cl2, rt; (j) 0.5 M LiOH, THF/MeOH/H2O (4:1:2), 0 °C to rt. Improved synthesis of the tripeptide thioester 14. Reagents and conditions: (a) SOCl2, EtOH, 78 °C; (b) IBCF, NMM, THF, −20 °C; (c) Pd/C, H2, MeOH, rt; (d) EDC, CuCl, CH2Cl2, rt; (e) 0.5 M LiOH, THF/H2O (4:1:2), 0 °C to rt; (f

Photoreversible stretching of a BAPTA chelator marshalling Ca²⁺-binding in aqueous media

• Aurélien Ducrot,
• Arnaud Tron,
• Robin Bofinger,
• Ingrid Sanz Beguer,
• Jean-Luc Pozzo and
• Nathan D. McClenaghan

Beilstein J. Org. Chem. 2019, 15, 2801–2811, doi:10.3762/bjoc.15.273

• (5-hydroxy-2,1- phenylene)nitrilo]tetraacetate (1c). A solution of 1b (4.13 g, 5.16 mmol) in methanol (150 mL) and 10% Pd/C (0.5 g) was stirred vigorously under a H2 atmosphere for 24 h at room temperature. The reaction mixture was subsequently filtered over celite and the celite pad was washed with

• mmol), 10% Pd/C (0.02 g) and a few drops of triethylamine in 100 mL DCM/EtOH 1:1 (v/v) was stirred vigorously under a hydrogen atmosphere for 48 h. The reaction mixture was filtered over celite and the celite pad washed with hot EtOAc. Column chromatography (SiO2, EtOAc) yielded the title compound

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

Sugar-derived oxazolone pseudotetrapeptide as γ-turn inducer and anion-selective transporter

• Sachin S. Burade,
• Sushil V. Pawar,
• Tanmoy Saha,
• Navanath Kumbhar,
• Amol S. Kotmale,
• Manzoor Ahmad,
• Pinaki Talukdar and
• Dilip D. Dhavale

Beilstein J. Org. Chem. 2019, 15, 2419–2427, doi:10.3762/bjoc.15.234

• converted to C-3-tetrasubstituted furanoid sugar azido ester 3 as per our reported protocol [12]. Hydrolysis of the ester functionality in 3 with LiOH at room temperature afforded azido acid 4a in 92% yield, while hydrogenation of 3 using 10% Pd/C in MeOH at room temperature for 3 h afforded the amino ester

• 4b in 86% yield (Scheme 1). The coupling of 4a and 4b using 2-chloro-1-N-methylpyridinium iodide (CMPI), as a coupling reagent, in the presence of Et3N in dichloromethane at 40 °C for 12 h gave azido ester dipeptide 5 in 75% yield. Hydrogenation of 5 using 10% Pd/C in methanol gave amino ester

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• /C (0.0145 g) was refluxed in dry ethanol (10 mL) for 1 h. After dropwise addition of hydrazine monohydrate (0.30 mL), the reaction mixture was refluxed overnight. After filtration of Pd/C and concentrating the filtrate to dryness, the resulting white solid (0.320 g) was identified as 4-amino-4’,4

• mmol) and Pd/C (0.0145 g) in dry ethanol (10 mL) was refluxed for 1 h. After dropwise addition of hydrazine monohydrate (0.30 mL), the reaction mixture was refluxed overnight. After filtration and concentrating the filtrate to dryness, the resulting white solid (0.320 g) was identified as 4-amino-4’,4

• JNM-ECP400 spectrometer with tetramethylsilane (TMS) as internal standard (0 ppm). EIMS measurements were performed using a JEOL JMS-700 MStation spectrometer. Synthesis and characterization of compounds Synthesis of 1a The mixture of 4,4’-dimethoxy-4’’-nitrotriphenylamine (0.351 g, 1.00 mmol) and Pd

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

• was isomerized in the presence of base and dehydrated to give diene 45. Reduction of 45 with 10% Pd/C afforded 8 in good yield (60%) after recrystallization. Benzylic oxidation of 8 (CrO3/HOAc, 45%), followed by C-14 ether cleavage (BBr3) and subsequent sodium borohydride reduction afforded 46 with

• mixture of 51 and 52, subsequent Pd/C-catalyzed hydrogenation and tetrabutylammonium fluoride (TBAF)-mediated desilylation yielding the desired tricyclic 54 (83% yield, 98% ee). Overall, the known intermediate 7-oxotriptophenlide 59 was obtained in an efficient, elegant and scalable way in 10 steps with

• 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

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

• %. Synthesis of C-modified desmuramyl peptides. Reagents and conditions: a) H2, 10% Pd/C, MeOH, 38 psi, rt, 24 h, 96%; b) adamant-1-ylamine hydrochloride, EDC·HCl, HOBt·H2O, Et3N, DCM/dioxane 1:1, 0 °C → rt, 48 h, 60%; c) TFA/DCM 1:2, rt, 1 h, quantitative. Synthesis of the mannose precursor. Reagents and

• % Pd/C, 48 h, rt, 83–92%. Synthesis of mannosylated peptides with glycolyl linker. Reagents and conditions: a) EDC·HCl, HOBt·H2O, Et3N, DCM/DMF 1:1, 0 °C → rt, 72 h, 26–67%; b) NaOMe/MeOH, rt, 1 h, 59–89%. Supporting Information Supporting Information File 520: Experimental and characterization data

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

Design and synthesis of multivalent α-1,2-trimannose-linked bioerodible microparticles for applications in immune response studies of Leishmania major infection

• Chelsea L. Rintelmann,
• Tara Grinnage-Pulley,
• Kathleen Ross,
• Daniel E. K. Kabotso,
• Angela Toepp,
• Anne Cowell,
• Christine Petersen,
• Balaji Narasimhan and
• Nicola Pohl

Beilstein J. Org. Chem. 2019, 15, 623–632, doi:10.3762/bjoc.15.58

• , hydrogenolysis of the benzyl ethers under continuous flow (0.3–1 mL/min) and H2 pressure (30–60 bar) using an H-cube apparatus was found to be effective at removing the benzyl ethers, but arduously slow (>48 h) from the limited surface-mediated interactions with the Pd/C cartridge. By comparison, batch

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• the amine using LiAlH4 with concomitant debenzoylation, followed by the acylation of the amine with lauric acid to afford 9a, and finally, ii) reductive cleavage by hydrogenolysis using Pd–C/H2 leading to debenzylation (Scheme 3). However, during hydrogenolysis, the elimination of the -OBn group led

• from 9. Conditions: (i) (a) LiAlH4 (1 M in THF)/THF/25 °C/3 h, (b) DCC/DMAP/lauric acid, CH2Cl2/25 °C/18 h; (ii) (a) H2/10% Pd–C/EtOH/25 °C or (b) DDQ/CH2Cl2–H2O 4:1/3 h. Actual synthesis of 2 from 9. Conditions: (i) DDQ/CH2Cl2–H2O 4:1/3 h; (ii) a) LiAlH4/THF/25 °C/3 h, b) DCC/DMAP/lauric acid, CH2Cl2

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• achieved in the presence of Pd/C as a catalyst. Concomitant hydrogenolysis of two carbon–chlorine bonds also took place under these conditions and a 71:29 diastereomeric mixture of the monochloracetamides 19f/19’f was obtained (41%). The rather small difference of steric hindrance between the methyl and

• -acylamino)cyclopropanes] possessing a single substituent at C2, it is possible to rely either on the steric hindrance or on the coordinating ability of the amide group. Thus, the hydrogenation of trifluoroacetamide 51 catalyzed by Pd/C afforded N-trifluoroacetylaminocyclopropane 55 as the major diastereomer

• by Rh/C occurred on the less hindered face of the alkene and gave rise to cyclopropyl α-alkoxy ester 72 as a single detectable diastereomer. When Pd/C was used as the catalyst, cleavage of the PMB group took place concomitantly and the α-hydroxy ester 73 arising from addition of hydrogen on the less