On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

• gemcitabine causes cell death (masked termination) [83]. Regarding the possible functional sites in gemcitabine that can be used for the construction of PDCs are its primary and secondary alcohols as also the amine (Figure 4). Paclitaxel (PTX): Paclitaxel (PTX) is a member of the taxane family and one of the

Acid-catalyzed ring-opening reactions of a cyclopropanated 3-aza-2-oxabicyclo[2.2.1]hept-5-ene with alcohols

• Katrina Tait,
• Alysia Horvath,
• Nicolas Blanchard and
• William Tam

Beilstein J. Org. Chem. 2017, 13, 2888–2894, doi:10.3762/bjoc.13.281

• 38% yield (Table 3, entry 7). The use of secondary alcohols generally resulted in a decrease of yield of the ring-opened product (Table 3, entries 8–11). Isopropanol achieved a moderate yield of 51% (Table 3, entry 8) while using 2-butanol decreased the yield to 28% of a 1:1 diastereomeric ratio of

Electron-deficient pyridinium salts/thiourea cooperative catalyzed O-glycosylation via activation of O-glycosyl trichloroacetimidate donors

• Mukta Shaw,
• Yogesh Kumar,
• Rima Thakur and
• Amit Kumar

Beilstein J. Org. Chem. 2017, 13, 2385–2395, doi:10.3762/bjoc.13.236

• ), benzyl alcohol (2c), 4-methoxy benzyl alcohol (2d), and secondary alcohols, e.g., cyclohexanol (2e), cyclopentanol (2f) produced their corresponding glucosides 5b–f in 78–88% yields and with moderate α-selectivity (Table 2, entries 1–5). It is important to note that, when a halogenated primary alcohol

Mechanically induced oxidation of alcohols to aldehydes and ketones in ambient air: Revisiting TEMPO-assisted oxidations

• Andrea Porcheddu,
• Evelina Colacino,
• Giancarlo Cravotto,
• Francesco Delogu and
• Lidia De Luca

Beilstein J. Org. Chem. 2017, 13, 2049–2055, doi:10.3762/bjoc.13.202

• primary and secondary alcohols to the corresponding aldehydes and ketones by mechanical processing under air. Ball milling was shown to promote the quantitative conversion of a broad set of alcohols into carbonyl compounds with no trace of an over-oxidation to carboxylic acids. The mechanochemical

• (2n) in a modest yield (39%) after 4 cycles (15 min per cycle). Unfortunately, prolonged milling times led to the decomposition of the final aldehyde. These promising results prompted us to undertake additional studies on secondary alcohols. The optimised ball milling protocol was applied to alcohols

• oxidation of 4-nitrobenzylic alcohol under mechanical activation conditions [65]. Scope of primary alcohols in oxidation under ambient air. Scope of secondary alcohols in oxidation under ambient air. Supporting Information Supporting Information File 278: Experimental part and NMR spectra

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• in good yields within 30 min of reaction time (Scheme 19) [87]. Various aromatic and aliphatic nitriles including acetonitrile, alcohols like tert-butanol and other secondary alcohols were used for this reaction. In case of solid nitriles 1.0 equiv of nitromethane was added during the grinding

Selective enzymatic esterification of lignin model compounds in the ball mill

• Ulla Weißbach,
• Saumya Dabral,
• Laure Konnert,
• Carsten Bolm and
• José G. Hernández

Beilstein J. Org. Chem. 2017, 13, 1788–1795, doi:10.3762/bjoc.13.173

• diameter) [9], demonstrated to efficiently mediate the enzymatic kinetic resolution of secondary alcohols under solvent-free conditions in both mixer and planetary ball mills (Scheme 1b) [10]. Interestingly, this latter lipase (a commercial preparation known as Novozyme 345, hereinafter referred as CALB

Mechanochemical enzymatic resolution of N-benzylated-β³-amino esters

• Mario Pérez-Venegas,
• Gloria Reyes-Rangel,
• Adrián Neri,
• Jaime Escalante and
• Eusebio Juaristi

Beilstein J. Org. Chem. 2017, 13, 1728–1734, doi:10.3762/bjoc.13.167

• applications on a large scale [45][46]. Very recently, Hernández, Frings, and Bolm developed a method to carry out the kinetic resolution of secondary alcohols through selective acylation using Candida antarctica lipase B, under solvent-free ball-milling conditions [47][48]. Inspired by this ground-breaking

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Effect of uridine protecting groups on the diastereoselectivity of uridine-derived aldehyde 5’-alkynylation

• Raja Ben Othman,
• Mickaël J. Fer,
• Laurent Le Corre,
• Sandrine Calvet-Vitale and
• Christine Gravier-Pelletier

Beilstein J. Org. Chem. 2017, 13, 1533–1541, doi:10.3762/bjoc.13.153

• first prepared primary alcohols 1–5 from uridine and differing by the nature of R1 protecting groups. The secondary alcohols at C-2’ and C-3’ were protected either as a cyclic ketal (isopropylidene (1a) [12], isopentylidene (2a), cyclohexylidene (3a)) or as acyclic silyl ethers (4a [15], R1 = TBDMS and

• approach of the nucleophile on the Re face: the bulkier the silyl group, the stronger the effect. Conclusion In summary, we report a study on the diastereoselective 5’-alkynylation of uridine aldehydes displaying various protecting groups on the secondary alcohols at C-2’ and C-3’ and at the N-3 position

Continuous N-alkylation reactions of amino alcohols using γ-Al₂O₃ and supercritical CO₂: unexpected formation of cyclic ureas and urethanes by reaction with CO₂

• Emilia S. Streng,
• Darren S. Lee,
• Michael W. George and
• Martyn Poliakoff

Beilstein J. Org. Chem. 2017, 13, 329–337, doi:10.3762/bjoc.13.36

• higher temperatures in both the presence and absence of scCO2. Increasing the primary alcohol length led to slightly lower yields of the target products whereas secondary alcohols did not react with the amines at all. Varying the chain length of the amino alcohol produced the corresponding N-alkylated

First DMAP-mediated direct conversion of Morita–Baylis–Hillman alcohols into γ-ketoallylphosphonates: Synthesis of γ-aminoallylphosphonates

• Marwa Ayadi,
• Haitham Elleuch,
• Emmanuel Vrancken and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2906–2915, doi:10.3762/bjoc.12.290

• phosphites gave the corresponding phosphonates 4b and 4c in 60–62% yields. The reaction of secondary alcohols 3b and 3c with trialkyl phosphites was also surveyed. Under the previous reaction conditions (solvent-free, 80 °C, without any additive) an SN2’-type reaction followed by an Arbuzov rearrangement

Orthogonal protection of saccharide polyols through solvent-free one-pot sequences based on regioselective silylations

• Serena Traboni,
• Emiliano Bedini and
• Alfonso Iadonisi

Beilstein J. Org. Chem. 2016, 12, 2748–2756, doi:10.3762/bjoc.12.271

• literature, and can even be further accelerated with a catalytic amount of tetrabutylammonium bromide (TBAB). The strategy proved also useful for either the selective TBDMS protection of secondary alcohols or the fast per-O-trimethylsilylation of saccharide polyols. In the second part of the paper the scope

• silylations with a minimal excess of pyridine, some effort was devoted to ascertain the feasible exploitation of a similar strategy to either regioselective di-O-silylations or the protection of secondary alcohols in absence of primary ones (Table 3). As a matter of fact, upon doubling the stoichiometric

• same time. Not unexpectedly, secondary alcohols exhibited a recalcitrant reactivity towards TBDPSCl under these solvent-free conditions, and the di-O-silylation process resulted in limited synthetic usefulness (data not shown). The scope of the solvent-free conditions was further examined in the

Identification, synthesis and mass spectrometry of a macrolide from the African reed frog Hyperolius cinnamomeoventris

• Markus Menke,
• Pardha Saradhi Peram,
• Iris Starnberger,
• Walter Hödl,
• Gregory F.M. Jongsma,
• David C. Blackburn,
• Mark-Oliver Rödel,
• Miguel Vences and
• Stefan Schulz

Beilstein J. Org. Chem. 2016, 12, 2731–2738, doi:10.3762/bjoc.12.269

• from Madagascar also use chemical cues. Macrocyclic lactones such as phoracantholide I (3), phoracantholide J (4) or gephyromantolide A (5), are released by males from femoral glands to serve as signals, often accompanied by secondary alcohols (Figure 1) [2][3][4]. Another frog family most likely using

Isosorbide and dimethyl carbonate: a green match

• Fabio Aricò and
• Pietro Tundo

Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218

• mentioned that generally methylation of secondary alcohols via DMC chemistry requires high temperatures (>150 °C) and was never obtained in high yield due to the formation of elimination products [88]. However, isosorbide, which incorporates in its backbone secondary hydroxy groups, was quantitatively

• molecule and at the same time the basic sites activate the substrate. Interestingly, isosorbide peculiar backbone seems to play a very important role in the methylation reaction via DMC chemistry. In fact when the methylation via DMC reaction was performed on other secondary alcohols in the best found

• co-polycarbonate via melt polycondensation. Synthesis of DMI via DMC chemistry. Comparison of the reactivity of isosorbide with other secondary alcohols in methylation reaction. Reaction conditions: Isosorbide DMC 1:50 equiv; reaction time 20 h; 90 °C. Top chemical opportunities from biorefinery

Silica-supported sulfonic acids as recyclable catalyst for esterification of levulinic acid with stoichiometric amounts of alcohols

• Raimondo Maggi,
• N. Raveendran Shiju,
• Veronica Santacroce,
• Giovanni Maestri,
• Franca Bigi and
• Gadi Rothenberg

Beilstein J. Org. Chem. 2016, 12, 2173–2180, doi:10.3762/bjoc.12.207

• h) and provides good to excellent yields with various primary and secondary alcohols. The selectivity towards desired products remained complete in all cases. The coproduct of the reaction, namely water, did not hamper the efficiency of this solvent-free process. The selected catalyst is cheap, can

• in our hands, we checked the scope of this catalytic methodology (Table 5). As expected, the best performances were obtained with primary alcohols (Table 5, entries 1 and 2), which afforded the desired ester in 93 and 79% yield, respectively. Gratifyingly, the method could be extended to secondary

• alcohols as isopropanol and L-menthol. Despite their increased steric hindrance, very good results were obtained with a selectivity towards 3 >99% (Table 5; entries 3 and 4, 59 and 76% yield). In particular, it is important to underline that a single diastereomer of product 3d was formed (Table 4, entry 4

The direct oxidative diene cyclization and related reactions in natural product synthesis

• Juliane Adrian,
• Leona J. Gross and
• Christian B. W. Stark

Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200

• contrast to other representatives of this subgroup of acetogenins they are lacking one of the secondary alcohols usually framing the bis-THF core (Scheme 14). They were isolated from the leaves of Rollinia mucosa [108] and shown to exhibit cytotoxicity against six human tumor cell lines. Rollidecin C (69

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

• transformation into geminal dihydroperoxide 190 was observed (Table 13). The formation of geminal dihydroperoxides 195 was also observed in the acid-catalyzed reaction of bicyclic secondary alcohols 192 with hydrogen peroxide. This reaction starts with the formation of bicyclic hydroperoxides 193 followed by the

Unconventional application of the Mitsunobu reaction: Selective flavonolignan dehydration yielding hydnocarpins

• Guozheng Huang,
• Simon Schramm,
• Jörg Heilmann,
• David Biedermann,
• Vladimír Křen and
• Michael Decker

Beilstein J. Org. Chem. 2016, 12, 662–669, doi:10.3762/bjoc.12.66

• Mitsunobu reaction represents a powerful method to convert primary and secondary alcohols into ester but also into various derivatives. The mechanism is well described and includes the formation of the triphenylphosphine–DIAD adduct, which then activates the alcohol making it a good leaving group

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

• binding constant values and the hydrophobicity of the pesticides, suggesting that steric effects are probably predominantly involved in complex formation. The inclusion of the apolar heterocyclic ring into the CD cavity is the most likely situation to occur. γ-CD has the largest secondary alcohols rim

Base metal-catalyzed benzylic oxidation of (aryl)(heteroaryl)methanes with molecular oxygen

• Hans Sterckx,
• Johan De Houwer,
• Carl Mensch,
• Wouter Herrebout,
• Kourosch Abbaspour Tehrani and
• Bert U. W. Maes

Beilstein J. Org. Chem. 2016, 12, 144–153, doi:10.3762/bjoc.12.16

• photoinduced oxidation of secondary alcohols [27]. Very recently the group of Zhuo and Lei disclosed an alteration to our reaction conditions to further extend the substrate scope [28]. Ethyl chloroacetate was used as the promotor instead of acetic acid, allowing the authors to additionally oxidize less

Cross metathesis of unsaturated epoxides for the synthesis of polyfunctional building blocks

• Meriem K. Abderrezak,
• Kristýna Šichová,
• Nancy Dominguez-Boblett,
• Antoine Dupé,
• Zahia Kabouche,
• Christian Bruneau and
• Cédric Fischmeister

Beilstein J. Org. Chem. 2015, 11, 1876–1880, doi:10.3762/bjoc.11.201

• conditions may result in the carbon–carbon double bond hydrogenation accompanied by ring opening of the epoxide leading to a mixture of primary and secondary alcohols [39]. A second and more straightforward method consists in the tandem metathesis/hydrogenation reaction where the residual ruthenium species

Preparation of conjugated dienoates with Bestmann ylide: Towards the synthesis of zampanolide and dactylolide using a facile linchpin approach

• Jingjing Wang,
• Samuel Z. Y. Ting and
• Joanne E. Harvey

Beilstein J. Org. Chem. 2015, 11, 1815–1822, doi:10.3762/bjoc.11.197

• aldehyde. Primary and secondary alcohols, including allylic alcohols, are suitable substrates; the newly formed alkene has an E-geometry. Strategically, this represents a highly efficient route to unsaturated polyketide derivatives. A linchpin approach to the synthesis of a major fragment of the natural

• -alkenes were ever observed with secondary alcohols. As the minor isomers were not able to be isolated, their identities are unconfirmed. After these promising results, the homopropargylic secondary alcohol 7a [42], representing the C16–C20 fragment of zampanolide, was subjected to Bestmann ylide linchpin

Photovoltaic-driven organic electrosynthesis and efforts toward more sustainable oxidation reactions

• Bichlien H. Nguyen,
• Robert J. Perkins,
• Jake A. Smith and
• Kevin D. Moeller

Beilstein J. Org. Chem. 2015, 11, 280–287, doi:10.3762/bjoc.11.32

• oxidize the primary alcohol of a glucose derivative in the presence of the unprotected secondary alcohols. Once again, this is an example of selectivity that cannot be accomplished with a direct electrochemical oxidation, which would select the oxidation based exclusively on potential. Again, the yield

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

• was used [181]. The reaction time is 18 h at 90 °C, the yields of α-ketoesters vary from 42 to 88%. The unusual C–O cross-coupling of primary alcohols 184 with secondary alcohols 185 in the absence of oxidants was performed in the presence of ruthenium complex 186 as the catalyst; the reaction

• afforded molecular hydrogen and unsymmetrical ester 187 (Scheme 39) [182]. Cross-coupling products 187 were obtained in high yields; the expected homocoupling of primary alcohols giving symmetrical esters and the dehydrogenation of secondary alcohols yielding ketones were avoided. 3 Ketones and 1,3

Visible-light-induced bromoetherification of alkenols for the synthesis of β-bromotetrahydrofurans and -tetrahydropyrans

• Run Lin,
• Hongnan Sun,
• Chao Yang,
• Youdong Yang,
• Xinxin Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2015, 11, 31–36, doi:10.3762/bjoc.11.5

• submitted to the optimized reaction conditions. As can be seen in Table 3, various styrenes were reacted efficiently to form the substituted tetrahydropyrans in high yield via 6-endo bromoetherification (Table 3, entries 1 and 2). Furthermore, not only primary alcohols but also secondary alcohols were