Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• influence of Zhan-1B catalyst 4 to deliver the cyclized product 131 (91%). Later, TFA-mediated deprotection of cyclized product 131 gave amine 132 (97%). Treatment of chloro derivative 132 with boronate ester 133 provided the SM coupling precursor 134 (77%). Later, an intramolecular SM coupling of Bpin

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• coupling to 16 and deprotection to 17 worked satisfyingly. As in the case of a benzene partial structure (8), it was a diol that was formed from 17 under McMurry conditions (20 equiv TiCl4, 40 equiv Zn, THF, rt). No alkene was detected. McMurry-type pinacol cyclizations have shown varying degrees of

• spectrum at 2.61 ppm. This indicates that the alkynyl side chain had been introduced from the same side as the ethoxycarbonyl group. By conversion of the ester to an aldehyde group and deprotection we obtained the subject of study, the putative cyclization precursor 25 (71%). In an orienting reaction

Nucleoside macrocycles formed by intramolecular click reaction: efficient cyclization of pyrimidine nucleosides decorated with 5'-azido residues and 5-octadiynyl side chains

• Jiang Liu,
• Peter Leonard,
• Sebastian L. Müller,
• Constantin Daniliuc and
• Frank Seela

Beilstein J. Org. Chem. 2018, 14, 2404–2410, doi:10.3762/bjoc.14.217

• and deprotection steps are necessary to control the cyclization process. Preorganization of the molecules can help to make cyclization more efficient. Azide–alkyne "click" chemistry has been executed to generate cyclic peptides [11][12][13], cyclic oligonucleotides [14][15][16][17] and other

Semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues

• Kai Zhang,
• Jiarong Li,
• Honglin Liu,
• Haiyou Wang and
• Lamusi A

Beilstein J. Org. Chem. 2018, 14, 2321–2330, doi:10.3762/bjoc.14.207

• spinetoram J. Compared with the previous semi-synthesis, selective protection and deprotection of the C9–OH and the C17–OH were simplified in this self-protection strategy, resulting in less synthetic steps and costs. During the selective hydrolysis of 3-O-ethyl-2,4-di-O-methylrhamnose at the C17 position

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

• Pamarthi Gangadhar,
• Sayini Ramakrishna,
• Ponneri Venkateswarlu and
• Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

• , respectively, followed by the desilylation (TBDPS removal) to yield the title products. The intermediate aldehyde 14 can be synthesized from ketone 17 in a four-step sequence by a stereoselective keto reduction, TBDPS protection, TBS deprotection and an oxidation reaction. The ketone 17 can be easily

• deprotection to give the primary alcohol which was subjected to oxidation to yield aldehyde 14a (Scheme 6). The latter was then subjected to a Wittig reaction with 15 followed by silyl deprotection as performed for 14 to furnish 9a (see Supporting Information File 1 for experimental details). The sign of the

Synthesis of a water-soluble 2,2′-biphen[4]arene and its efficient complexation and sensitive fluorescence enhancement towards palmatine and berberine

• Xiayang Huang,
• Xinghua Zhang,
• Tianxin Qian,
• Junwei Ma,
• Lei Cui and
• Chunju Li

Beilstein J. Org. Chem. 2018, 14, 2236–2241, doi:10.3762/bjoc.14.198

• reaction sites was quantitatively prepared by the deprotection of 2,2’-OEtBP4 using excess BBr3. The nucleophilic substitution reaction of 2,2’-OHBP4 and ethyl bromoacetate, K2CO3 as the base, afforded 2,2’-COOEtBP4 in 88% yield. The hydrolysis of 2,2’-COOEtBP4 in NaOH solution and then acidification with

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• equivalents of a strong base such as CsOH yields quantitatively the corresponding cesium thiolates B and D which are quite stable under standard Schlenk conditions. Addition of an alkyl halide can attach a broad range of different substituents. The cyanoethyl group allows a sequential deprotection and

• breakthroughs for the construction of TTF-based supramolecular architectures: (b) Stepwise deprotection/alkylation, (c) phosphite-mediated heterocoupling, and (d) pyrrolo-annulated TTF derivatives I and J. (a) Host–guest equilibrium between π-electron-poor cyclophane 3 and different TTFs with their

Studies towards the synthesis of hyperireflexolide A

• G. Hari Mangeswara Rao

Beilstein J. Org. Chem. 2018, 14, 2106–2111, doi:10.3762/bjoc.14.185

• with 2-bromopropene followed by lactonization. Enone 3 could be synthesized from 4 by installation of the methyl group at C-10 followed by cross metathesis reaction. Compound 4 could be obtained from the γ-lactone-fused cyclopentane 5 by deprotection of C-9 followed by allylation at C-8. Previously, we

Chiral bisoxazoline ligands designed to stabilize bimetallic complexes

• Deepankar Das,
• Rudrajit Mal,
• Nisha Mittal,
• Zhengbo Zhu,
• Thomas J. Emge and
• Daniel Seidel

Beilstein J. Org. Chem. 2018, 14, 2002–2011, doi:10.3762/bjoc.14.175

• provided oxazoline 28. Following deprotection, the resulting amine 29 was allowed to react with half an equivalent of the pyrazole diacyl chloride 23 to yield the pyrazole-bridged bisoxazoline ligand 30-H3. Initial experiments have shown that the trianionic ligand 30-H3 readily forms complexes with various

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• groups in the 1H NMR spectra fully corresponded to the proposed structures of 9 and 11 (Supporting Information File 1, Figures S9, S10, S13, and S14). The polyamines 10a,b and 12a,b were obtained in high yields after BOC deprotection with HCl in dioxane as water-soluble di- and tetrahydrochlorides

Cationic cobalt-catalyzed [1,3]-rearrangement of N-alkoxycarbonyloxyanilines

• Itaru Nakamura,
• Mao Owada,
• Takeru Jo and
• Masahiro Terada

Beilstein J. Org. Chem. 2018, 14, 1972–1979, doi:10.3762/bjoc.14.172

• ][21][22][23][24]. In addition, the reaction of 1h-18O (23% 18O) in the absence of the cationic cobalt catalyst at 140 °C followed by hydrogenative deprotection afforded 4h, of which the oxygen-18 content was less than 2% (Scheme 3c). Therefore, we concluded that the cationic cobalt catalyst not only

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• with 4-[N-(tert-butyloxycarbonyl)]amino-1-butanal [37] followed by Boc deprotection with TFA. 4 was prepared by a substitution reaction from the parent meso-pentafluorobenzyl-BODIPY BDP-F5 with aminomethylcyclohexane (route C), following an established synthetic approach [38]. For the preparation of

Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester

• Takao Shoji,
• Hiroki Fukutomi,
• Yohei Okada and
• Kazuhiro Chiba

Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169

• , chemical syntheses can technically be divided into two parts; deprotection and coupling reactions, enabling simple repeated procedures for their production, and bioactivities can potentially be tuned by alteration of their sequences. Nowadays, not only canonical amino acids and/or nucleosides but also

• bioconjugation product 4 and basic deprotection gave the native form 5 with a naturally occurring linkage in 70% yield over 5 steps. The impurities can reasonably be assigned as the hydrolized and/or oxidized products of the 5’-activated supported trinucleotide 2 [75]. In order to investigate the generality of

• specific sequences can cause aggregation and thus severely inhibit further reactions; however, our support could possibly address such technical problems. Gratifyingly, although further optimization of the reaction conditions is needed for the deprotection reactions (see Schemes S5 and S6 in Supporting

Assessing the possibilities of designing a unified multistep continuous flow synthesis platform

• Mrityunjay K. Sharma,
• Roopashri B. Acharya,
• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2018, 14, 1917–1936, doi:10.3762/bjoc.14.166

• ) condensation b) aromatic nucleophilic substitution reaction, c) deprotection and d) formation of lactate salt. Details of the same are given below: Condensation: Condensation takes place in a first reactor TR1 between the nitrile and hydrazine at high temperature and under pressure. Here, the nitrile was

• . Here the reactor was maintained at a temperature of 70–100 °C for 1–3 hours. The product was crystallized in CT1 with the anti-solvent methanol pumped through P4 into the crystallization tank. The crystallized product was filtered and separated in S2. Deprotection: The second-stage product from the

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

• Bimal Koirala,
• Robert A. Hillman,
• Erin K. Tiwold,
• Michael A. Bertucci and
• Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

• of 0.2 M. Reactions were run at 50 W at a temperature of 75 °C for 8 minutes, followed by 2 × 3 min deprotection with 20% piperidine in DMF. Peptide purification. Crude peptides were purified with RP-HPLC. The crude peptide was dissolved in ACN/H2O (1:4) and purified in 2.0–2.4 mL portions on either

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• in the IR spectrum of 4. Phenanthroline derivative 5 was synthesized from 5-glycinamido-1,10-phenanthroline in a two-step sequence consisting of a peptide-type coupling reaction with a Boc-protected glycine N-hydrosuccinimide ester followed by the deprotection of the amino group (see Supporting

An amine protecting group deprotectable under nearly neutral oxidative conditions

• Shahien Shahsavari,
• Chase McNamara,
• Mark Sylvester,
• Emily Bromley,
• Savannah Joslin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2018, 14, 1750–1757, doi:10.3762/bjoc.14.149

• . Deprotection was performed by oxidation followed by treating with a weak base. The yields were good to excellent. The new amino protecting group offers a different dimension of orthogonality in reference to the commonly used amino protecting groups in terms of deprotection conditions. It is expected to allow a

• carbamate and 6-nitroveratryl carbamate) [9][10] and fluoride (e.g., trimethylsilylethyloxycarbonyl (Teoc) group) [11][12]. The 1,3-dithian-2-ylmethoxycarbonyl (Dmoc) group first reported by Kunz and co-workers provides a different dimension of orthogonality of amine protection in terms of deprotection

• Dmoc group for amine protection in automated solid-phase oligodeoxynucleotide (ODN) synthesis [18]. For deprotection, we found that sodium periodate could effectively oxidize multiple Dmoc functions in the ODNs to achieve complete deprotection. Under these oxidative conditions, oxidation of the ODN was

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• block A [1,3,5-tris(piperazinomethyl)benzene] consisted of the amination of 1,3,5-tris(bromomethyl)benzene with commercially available N-Boc-piperazine followed by deprotection, and was achieved according to the literature [39] (97% overall yield in our hands). Similarly, 2,4,6-tris[(4-hydroxy

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• the N-Boc protected β-hydroxy sulfide 130 as a key intermediate. Deprotection of the Boc followed by the imidation of the free amine with protected dipeptides that mimic Leu-Val produced the inhibitors of human renin 131 as depicted in Scheme 44. Yoshioka and co-workers reported two synthetic routes

Heterogeneous acidic catalysts for the tetrahydropyranylation of alcohols and phenols in green ethereal solvents

• Ugo Azzena,
• Massimo Carraro,
• Gloria Modugno,
• Luisa Pisano and
• Luigi Urtis

Beilstein J. Org. Chem. 2018, 14, 1655–1659, doi:10.3762/bjoc.14.141

• to acid-catalyzed deprotection with H2SO4@SiO2 (25 wt % [33] as depicted in Scheme 3). Alcohol 1i, was recovered as a single stereoisomer, identical to the commercially available starting material, as determined by 1H and 13C NMR analysis of the crude reaction mixture (see Supporting Information File

• starting materials, was detected. aNo reaction in the presence of comparable amounts of NH4Br or SiO2. b1e is almost insoluble in CPME. c1:1 mixture of diastereoisomers. Deprotection of THP ether 3i. One-pot synthesis of 3-[4-(tetrahydro-2H-pyran-2-yl)oxymethylphenyl]-3-pentanol (4fa). One-pot synthesis of

Glycosylation reactions mediated by hypervalent iodine: application to the synthesis of nucleosides and carbohydrates

• Yuichi Yoshimura,
• Hideaki Wakamatsu,
• Yoshihiro Natori,
• Yukako Saito and
• Noriaki Minakawa

Beilstein J. Org. Chem. 2018, 14, 1595–1618, doi:10.3762/bjoc.14.137

• by manipulations of 5. After acetal hydrolysis and the subsequent hydride reduction, 4-thioarabinose derivative 9 was obtained in good yield. Introduction of a TBDPS group at the primary hydroxy group of 9, oxidation and Wittig reaction, followed by deprotection of the benzyl group, gave allyl

• give the desired 4’-selenouridine and 4’-selenocytidine derivatives in moderate yields. Deprotection of the nucleoside derivatives afforded 4’-selenouridine and 4’-selenocytidine, respectively [48] (Scheme 9). In the year in which the first synthesis of 4’-selenonucleoside was reported, Jayakanthan et

Phosphoramidite building blocks with protected nitroxides for the synthesis of spin-labeled DNA and RNA

• Timo Weinrich,
• Eva A. Jaumann,
• Ute M. Scheffer,
• Thomas F. Prisner and
• Michael W. Göbel

Beilstein J. Org. Chem. 2018, 14, 1563–1569, doi:10.3762/bjoc.14.133

• deprotection and enzymatic ligation. Amidite 6 has been applied to synthesize a full-length TAR RNA labeled with two nitroxide precursors. In the last step, the 2-nitrobenzyloxymethyl groups were removed by irradiation at 365 nm. After elimination of formic aldehyde induced by gentle heating, the resulting

• phosphoramidite building blocks 5, 7, and 8 have been used to prepare a series of self-complementary DNA (22a–25a) and RNA oligonucleotides (26a, 27a), each containing one protected TEMPO label (Figure 2). Chain assembly and deprotection proceeded uneventfully (Supporting Information File 1, Figures S1–S3). All

• oligonucleotides were purified by anion exchange and reversed-phase HPLC and characterized by mass spectrometry (Supporting Information File 1, Figures S4–S9). Upon photochemical deprotection (365 nm), the primary products are the hemiacetals 22b–27b (Supporting Information File 1, Figure S10). They still prevent

Metal-free formal synthesis of phenoxazine

• Gabriella Kervefors,
• Antonia Becker,
• Chandan Dey and
• Berit Olofsson

Beilstein J. Org. Chem. 2018, 14, 1491–1497, doi:10.3762/bjoc.14.126

• cyclization step. Attempts to perform the cyclization with t-BuOK and DMEDA only resulted in byproduct formation. The deprotection of 2 is reported to proceed in high yield [18], and the synthesis of 2 hence constitutes a metal-free formal synthesis of phenoxazine (1). The complete route is depicted in Scheme

•  7 and delivered N-acetylphenoxazine (2) in 72% overall yield over 3 steps. Combined with the literature yield for the deprotection, this would provide the target 1 in 65% overall yield based on recovered 3. The required starting materials in this route can easily be further substituted; hence we

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• sequence including protection/deprotection steps for the benzyl groups. The catalytic efficiency of calix[4]arene-based phase-transfer catalyst 7 was evaluated in the benchmark reaction (Scheme 3) and compared with that of the chiral quaternary ammonium salt 8. The results obtained when 7 used as

• enantiomerically pure (S)-(2-diphenylthiophosphinoferrocenyl)methanol. Deprotection of the thiophosphine unit(s) by tris(dimethylamino)phosphine gave chiral calixarene phosphines 27–29 bearing ferrocenyl substituents on the lower rim in high yields. Calixarene-derived mono(ferrocenylphosphine) ligands 27 and 28

• . reported the synthesis of a series of prolinamide and hydroxyprolinamide organocatalysts based on the calix[4]arene scaffold (Figure 8) [59]. Treatment of Boc-protected-L-proline or hydroxyproline with various aminocalix[4]arenes under one of the appropriate coupling conditions and subsequent deprotection

Acyl-group specificity of AHL synthases involved in quorum-sensing in Roseobacter group bacteria

• Lisa Ziesche,
• Jan Rinkel,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2018, 14, 1309–1316, doi:10.3762/bjoc.14.112

• with cysteamine into the protected thiol 8 [39]. Steglich esterification [40] with different free acids led to nine saturated PCEs 10a–i, four monounsaturated acids (11a–d), 3-OH-C10:0-HSL PCE (12), and 2E,11Z-C18:2-PCE (13) after deprotection with acetic acid [41]. Although compounds 10–13 can be