Development of variously functionalized nitrile oxides

• Haruyasu Asahara,
• Keita Arikiyo and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2015, 11, 1241–1245, doi:10.3762/bjoc.11.138

• anion for the hydrolysis was not required, and carboxylic acid 5a was obtained in 81% yield by the addition of only water (Table 3, entry 1). This protocol was applicable to a relatively bulky alcohol to afford isopropyl ester 5k in moderate yield (Table 3, entry 2). Similarly, primary and secondary

New palladium–oxazoline complexes: Synthesis and evaluation of the optical properties and the catalytic power during the oxidation of textile dyes

• Rym Hassani,
• Mahjoub Jabli,
• Yakdhane Kacem,
• Jérôme Marrot,
• Damien Prim and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2015, 11, 1175–1186, doi:10.3762/bjoc.11.132

• reaction mixture at room temperature [29]. In the light of these results, we also attempted to carry out this process under milder conditions. When (S)-4-isopropyl-2-(naphthalen-1-yl)oxazoline (2) was added to an acetic acid solution of Pd(OAc)2, a yellowish precipitate was obtained and identified as (S,S

• (Pd–N16 distance (1.963 A°), Pd–N1 distance (2.031 A°)) are almost the same (Pd–Cl1 distance (2.281 A°), the Pd–Cl2 distance (2.259 A°)). On the other hand, the addition of (S)-4-isopropyl-2-(naphthalen-1-yl)oxazoline (2) and 3-[(4S)-4,5-dihydro-4-isopropyl-1,3-oxazol-2-yl]propanenitrile (11) to a

• amino acids). (S)-4-Isopropyl-2-(naphthalen-1-yl)oxazoline (2) was isolated in a moderate yield from the condensation of the L-valinol with naphthonitrile under microwave irradiation, while the second ligand 1,2-bis[(S)-4-phenyloxazoline]benzene (7) was synthesized from L-(α)-(+)-phenylglycinol under

Cathodic hydrodimerization of nitroolefins

• Michael Weßling and
• Hans J. Schäfer

Beilstein J. Org. Chem. 2015, 11, 1163–1174, doi:10.3762/bjoc.11.131

• new reaction proceeds through a radical anion of the nitroalkene generated in a catalytic redox process. For ß-isopropyl-nitroethylene the radical anion has been identified by ESR [20]. Results and Discussion Investigation of the cathodic hydrodimerization of nitroalkene 1 to hydrodimer 2 The cathodic

Thiazole formation through a modified Gewald reaction

• Carl J. Mallia,
• Lukas Englert,
• Gary C. Walter and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2015, 11, 875–883, doi:10.3762/bjoc.11.98

• yields (hydrolysis occurs from generated water) than the corresponding ethyl analogues (entries 1, 2 and 9, 10, Table 4). The isopropyl ester leads to a lower conversion and isolated yield presumably as a consequence of steric interactions (entry 3, Table 4). Changing the electronic character of the

• 13 and 14, Table 4) but an isopropyl group such as in molecule 47 (Figure 2), reproducibly gave no product, indicating the steric limits of the reaction. Although the reaction appears general, certain substrates tested did not generate any product when employing the standard reaction conditions

3α,5α-Cyclocholestan-6β-yl ethers as donors of the cholesterol moiety for the electrochemical synthesis of cholesterol glycoconjugates

• Aneta M. Tomkiel,
• Adam Biedrzycki,
• Jolanta Płoszyńska,
• Dorota Naróg,
• Andrzej Sobkowiak and
• Jacek W. Morzycki

Beilstein J. Org. Chem. 2015, 11, 162–168, doi:10.3762/bjoc.11.16

• amounts of diene 13 and cholesteryl chloride (14) were also formed. In the reactions of i-cholesterol alkyl ethers (methyl 6b, ethyl, 6c, isopropyl 6d, and benzyl 6e), cholesterol glycoconjugate 11 was also formed in 40%, 51%, 41%, and 50% yield, respectively. Glycoconjugate 11 was accompanied by

• -cyclocholestan-6β-yl isopropyl ether (6d). See the Supporting Information File 1 for full experimental data. Cyclic voltammograms registered in 0.2 M tetrabutylammonium tetrafluoroborate (TBABF4) in dichloromethane on a platinum electrode (area, 0.008 cm2) of (a) the supporting electrolyte (black), (b) 1,2:3,4

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

• synthesized also from aromatic aldehydes, α,β-unsaturated aldehydes, or allylic alcohols in the presence of the DDQ (2,3-dichloro-5,6-dicyanobenzoquinone)/amberlyst-15 system in a methanol/toluene mixture under microwave irradiation [171]. Methyl, ethyl, and isopropyl benzoates were prepared from benzaldehyde

A study on the inhibitory mechanism for cholesterol absorption by α-cyclodextrin administration

• Takahiro Furune,
• Naoko Ikuta,
• Yoshiyuki Ishida,
• Hinako Okamoto,
• Daisuke Nakata,
• Keiji Terao and
• Norihiro Sakamoto

Beilstein J. Org. Chem. 2014, 10, 2827–2835, doi:10.3762/bjoc.10.300

• C18 (4.6 mm × 150 mm, Nihon Waters, Tokyo, Japan). The column temperature was 40 °C. The mobile phase was a mixture of acetonitrile and isopropyl alcohol (8:2, v/v). The flow rate was 0.6 mL/min. UV detection was carried out at 208 nm. A limit of detection of 0.15 μg mL−1 was obtained at a signal-to

Stereoselective synthesis of perillaldehyde-based chiral β-amino acid derivatives through conjugate addition of lithium amides

• Zsolt Szakonyi,
• Reijo Sillanpää and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2014, 10, 2738–2742, doi:10.3762/bjoc.10.289

• synthesis of β-peptides and 1,3-heterocycles in three steps. The steric effects of the isopropyl group at position 4 and of the α-methyl substituent of (R)-N-benzyl-N-α-methylbenzylamine on the reactivity were also studied and, upon application of a chiral amine, excellent stereoselectivity of the conjugate

• -based chiral β-amino acid derivatives derived from commercially available (−)-perillaldehyde (1). These 4-isopropyl-substituted analogues of ACHC (2-aminocyclohexanecarboxylic acid) might serve as promising building blocks for the synthesis of chiral 1,3-heterocycles and foldamers [7][11][23][35

• subsequently converted to the tert-butyl ester (3) [37]. In order to study the steric effect of the more bulky isopropyl group on the Michael addition, (4S)-tert-butyl phellandrate (6) was prepared via (4S)-phellandral (4) and (4S)-phellandric acid (5) (Scheme 1) [38][39][40]. The asymmetric Michael addition

Autonomous assembly of synthetic oligonucleotides built from an expanded DNA alphabet. Total synthesis of a gene encoding kanamycin resistance

• Kristen K. Merritt,
• Kevin M. Bradley,
• Daniel Hutter,
• Mariko F. Matsuura,
• Diane J. Rowold and
• Steven A. Benner

Beilstein J. Org. Chem. 2014, 10, 2348–2360, doi:10.3762/bjoc.10.245

• inserted gene encoding kanamycin resistance (or, for that matter, any insert at all). To assess whether the assembly had produced a gene able to confer kanamycin resistance, these cells were subcultured in shaken growth medium containing kanamycin and isopropyl β-D-1-thiogalactopyranoside (IPTG). Continued

• incubated with shaking at 37 °C until OD reached 1.4. Volumes (25 and 50 µL) of this culture were then plated (with appropriate serial dilutions) on agar containing ampicillin alone (to count cells that had been transformed regardless of the success of the OligArch assembly), kanamycin and isopropyl β-D

(CF₃CO)₂O/CF₃SO₃H-mediated synthesis of 1,3-diketones from carboxylic acids and aromatic ketones

• JungKeun Kim,
• Elvira Shokova,
• Victor Tafeenko and
• Vladimir Kovalev

Beilstein J. Org. Chem. 2014, 10, 2270–2278, doi:10.3762/bjoc.10.236

• (indanones, tetralone, acetophenones, 2-acetylthiophene and methyl benzyl ketone) with alkanoic acids RCOOH 1d–h (where R = 1-adamantylmethyl, neopentyl, isopropyl, methyl, phenyl) gave the corresponding β-diketones 3c–t in 37–86% yields (Table 2). In most cases reactions were carried out at the molar ratios

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• structure. The excellent regioselectivities and enantioselectivities resulted from the existence of the two isopropyl substituents in the chiral phosphine A2, which effectively controlled the approach of the acrylate toward the plausible phosphine/allenoate zwitterionic intermediate. Although the yields

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• stereochemistry of the AT reaction was reported by Reiff and Aaron [29]. They used enantiopure O-isopropyl methylphosphonite 7-1 (Scheme 7-i) as a substrate. This substrate was purified by distillation with no racemization. However, rapid racemization was observed when 7-1 was treated with sodium methoxide in

Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• derivative with limited stability, which was immediately converted into alcohol 4 by diastereoselective Felkin–Anh type Grignard addition with isopropyl magnesium chloride (50% yield over 2 steps from 3, dr > 95:5). However, we could not confirm that the use of diethyl ether as co-solvent in the Grignard

• acyclic D-serinal derivatives for the addition of nucleophiles to amino acid-derived aldehydes [33][34]. However, Zhu and co-workers have pointed out that Garner’s aldehyde surprisingly furnishes the syn diastereomer as the major product from its reaction with isopropyl magnesium chloride [32], thus

Synthesis of zearalenone-16-β,D-glucoside and zearalenone-16-sulfate: A tale of protecting resorcylic acid lactones for regiocontrolled conjugation

• Hannes Mikula,
• Julia Weber,
• Dennis Svatunek,
• Philipp Skrinjar,
• Gerhard Adam,
• Rudolf Krska,
• Christian Hametner and
• Johannes Fröhlich

Beilstein J. Org. Chem. 2014, 10, 1129–1134, doi:10.3762/bjoc.10.112

• protection of the more nucleophilic 4’-phenol and subsequent glucosylation or sulfation should lead to the desired products. For the development of a reliable protective group strategy and subsequent reaction optimization, 2,4-dihydroxybenzoic acid isopropyl ester (9) [29] was used as a RAL mimic. For

Consecutive isocyanide-based multicomponent reactions: synthesis of cyclic pentadepsipeptoids

• Angélica de Fátima S. Barreto,
• Otilie E. Vercillo,
• Ludger A. Wessjohann and
• Carlos Kleber Z. Andrade

Beilstein J. Org. Chem. 2014, 10, 1017–1022, doi:10.3762/bjoc.10.101

• its structure five side chains attached to the α carbon atoms: one isopropyl, one benzyl and three isobutyl groups. To generate the pentapeptoid analogues of San A, the side chain groups isobutyl, isopropyl and benzyl linked to the α carbon atom present in the peptide were moved to the nitrogen atoms

• . It was decided to keep at least one benzyl group in the structure of the peptoids and vary the isopropyl and isobutyl groups, thus maintaining a greater similarity with the structure of the San A depsipeptide. The retrosynthetic analysis of the depsipeptoids (Scheme 1) shows that the proposed

• added under pseudo-high dilution conditions (addition rate: 0.6 mL/h; addition time: 83 h; concentration: 0.80 mmol/L) to a suspension of paraformaldehyde 4, triethylamine, sodium sulfate and isopropyl/isobutyl/tert-butyl isocyanide 12a–c in methanol to yield the target cyclic pentadepsipeptoids 2a–f

Visible light mediated intermolecular [3 + 2] annulation of cyclopropylanilines with alkynes

• Theresa H. Nguyen,
• Soumitra Maity and
• Nan Zheng

Beilstein J. Org. Chem. 2014, 10, 975–980, doi:10.3762/bjoc.10.96

• . Hindered cyclopropylanilines, such as those possessing an ortho-isopropyl group, were satisfactorily converted to the annulation products (6 and 12). With respect to the other annulation partner, terminal alkynes substituted with an electron-withdrawing group were typically required for the annulation

A convenient enantioselective decarboxylative aldol reaction to access chiral α-hydroxy esters using β-keto acids

• Zhiqiang Duan,
• Jianlin Han,
• Ping Qian,
• Zirui Zhang,
• Yi Wang and
• Yi Pan

Beilstein J. Org. Chem. 2014, 10, 969–974, doi:10.3762/bjoc.10.95

• did not improve in the cases of methyl, isopropyl or benzyl esters (Table 2, entries 2–4). The mechanism of the reaction was proposed based on the kinetic studies of the malonic acid half thioester system by Shair [33]. Essentially β-keto acids can undergo decarboxylation or deprotonation to generate

A novel family of (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids – analogues of α-amino acids

• Natalia V. Pavlenko,
• Tatiana I. Oos,
• Yurii L. Yagupolskii,
• Igor I. Gerus,
• Uwe Doeller and
• Lothar Willms

Beilstein J. Org. Chem. 2014, 10, 722–731, doi:10.3762/bjoc.10.66

• recrystallized from water to give 19b (0.6 g, 97%). The overall yield of 19b is 0.92 g (87%). See Supporting Information for details of the syntheses, characteristics and NMR spectra of all new compounds. Synthesis of (trifluoromethyl)phosphinic acid (1) and ethyl and isopropyl esters 2–4. Reagents and

Tuning the interactions between electron spins in fullerene-based triad systems

• Maria A. Lebedeva,
• Thomas W. Chamberlain,
• E. Stephen Davies,
• Bradley E. Thomas,
• Martin Schröder and
• Andrei N. Khlobystov

Beilstein J. Org. Chem. 2014, 10, 332–343, doi:10.3762/bjoc.10.31

• for 2 h. On removal of solvent, the resulting residue was dissolved in CS2 (40 mL) by sonication, and any undissolved material removed by filtration. The filtrate was concentrated and purified by column chromatography (silica gel, o-dichlorobenzene/isopropyl alcohol 99.5:0.5) to give the product which

• then removed. The resulting residue dissolved in CS2 (40 mL) by sonication, and the undissolved material removed by filtration. The filtrate was concentrated and purified by column chromatography (silica gel, o-dichlorobenzene/isopropyl alcohol 99.5:0.5) to give the product which was washed with MeOH

Total synthesis and cytotoxicity of the marine natural product malevamide D and a photoreactive analog

• Werner Telle,
• Gerhard Kelter,
• Heinz-Herbert Fiebig,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2014, 10, 316–322, doi:10.3762/bjoc.10.29

• an identical ester section composed of dolaproine and (2S)-3-phenylpropan-1,2-diol. On the N-terminal side, the isopropyl and two sec-butyl side chains of isodolastatin H (2) are replaced by one sec-butyl and two isopropyl side chains, respectively, in the case of malevamide D (1). The total

Decandrinin, an unprecedented C₉-spiro-fused 7,8-seco-ent-abietane from the Godavari mangrove Ceriops decandra

• Hui Wang,
• Min-Yi Li,
• Félix Zongwe Katele,
• Tirumani Satyanandamurty,
• Jun Wu and
• Gerhard Bringmann

Beilstein J. Org. Chem. 2014, 10, 276–281, doi:10.3762/bjoc.10.23

• , 195.9), and a lactone carbonyl group (δC 170.9). The NMR spectroscopic data indicated that 1 was a rearranged abietane. The existence of an isopropyl group was suggested by 1H,1H-COSY correlations between H-15 and protons of two methyl groups [δH 1.11 (d, J = 6.9 Hz, 3H), 1.11 (d, J = 6.9 Hz, 3H)]. From

• 1H,1H-COSY correlations, three further proton–proton spin systems, viz. H2-1–H2-2, H2-11–H2-12, and H-5–H2-6, were deduced (Figure 2). HMBC correlations between H3-16/C-13, H3-17/C-13, and H-14/C-15 placed the above isopropyl group at C-13, while those from H-14 to C-9 and C-12 indicated the presence

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

• hydrazine (Me2C=N–NH2) was obtained. The channel involves two likely proton-transfer routes. However, it was found that the base-free reaction was unlikely at the N2 extrusion step from the isopropyl diimine intermediate (Me2C(H)–N=N–H). Two base-catalyzed reactions were investigated by models of the ketone

• , H2N–NH2 and OH−(H2O)7. Here, ketones are acetone and acetophenone. While routes of the ketone → hydrazone → diimine are similar, those from the diimines are different. From the isopropyl diimine, the N2 extrusion and the C–H bond formation takes place concomitantly. The concomitance leads to the

• diimine, many TS searches of diimine + (H2O)9 → C3H7– + N2 + H3O+(H2O)8 were attempted but failed. Instead, TS5 with concomitant proton transfers involving four water molecules was obtained in (xi). TS5 leads to the propane product without intervention of the isopropyl anion C3H7−. The product is shown in

Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

• Julian Fischer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2803–2811, doi:10.3762/bjoc.9.315

• randomly methylated β-cyclodextrin (RAMEB-CD) were added (9β). After that, the cloud point shifted significantly up to 36 °C, which is remarkable since PNIPAM does not interact with β-CD [14]. Explanation for this can be steric effects, since the isopropyl group in our system 9 is placed not so close at

• could be observed (Supporting Information File 1). To confirm the interaction of the isopropyl, respectively lactam moiety with RAMEB-CD we performed 2D ROESY NMR spectroscopy in D2O. The protons of the isopropyl group of 5 can be assigned to the proton resonances at 1.1 ppm. As illustrated in Figure 3a

• after addition of RAMEB-CD 10β. 2D NMR ROESY (300 MHz, D2O) spectrum of the complex of 5 with RAMEB-CD (a), displaying the correlation of the isopropyl moiety with RAMEB-CD and of 7 with RAMEB-CD (b), illustrating the interaction of the lower lactam ring with RAMEB-CD. Oscillatory rheological

Multigramme synthesis and asymmetric dihydroxylation of a 4-fluorobut-2E-enoate

• James A. B. Laurenson,
• John A. Parkinson,
• Jonathan M. Percy,
• Giuseppe Rinaudo and
• Ricard Roig

Beilstein J. Org. Chem. 2013, 9, 2660–2668, doi:10.3762/bjoc.9.301

• the highest enantiomeric purity possible to be competitive with syntheses from enantiomerically pure natural products. n-Propyl and isopropyl esters 21 and 22 were prepared (0.5 mol scale) to moderate the volatility of intermediates, while retaining the option of distillation as a method of

• can be made in much higher yield, and the n-propyl ester can be cleaved under milder conditions than the isopropyl ester in 26. Although the commercial AD-mixes (0.4 mol % osmium/1 mol % ligand) can transform most standard substrates smoothly, osmium tetroxide is an electrophilic reagent [22], and