Synthesis of functionalized macrocyclic derivatives of trioxabicyclo[3.3.0]nonadiene

• Sabine Leber,
• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2012, 8, 738–743, doi:10.3762/bjoc.8.83

• 11. Reductions with NaBH4 and sulfur [13] or with ammonium formate and Pd/C under microwave irradiation [14] were unsuccessful. However, compound 8 was completely reduced to the diamine 9 by using the classical reduction with Sn and HCl (Scheme 2). The reaction was complete in 1 h. Under the same

Stereoselective, nitro-Mannich/lactamisation cascades for the direct synthesis of heavily decorated 5-nitropiperidin-2-ones and related heterocycles

• Pavol Jakubec,
• Dane M. Cockfield,
• Madeleine Helliwell,
• James Raftery and
• Darren J. Dixon

Beilstein J. Org. Chem. 2012, 8, 567–578, doi:10.3762/bjoc.8.64

• /lactamisation cascade. Protodenitration of 5-nitropiperidin-2-ones. Various reductions of denitrated heterocycles. Supporting Information Supporting Information File 152: General experimental, copies of 1H and 13C NMR spectra for all new compounds (1a–j, 2a, 2a’’, 2m, 2m’, 6b–e, 10a–d, 11a–c, 12a,b

Self-assembly of Ru₄ and Ru₈ assemblies by coordination using organometallic Ru(II)₂ precursors: Synthesis, characterization and properties

• Sankarasekaran Shanmugaraju,
• Dipak Samanta and
• Partha Sarathi Mukherjee

Beilstein J. Org. Chem. 2012, 8, 313–322, doi:10.3762/bjoc.8.34

• found to be entirely different. Macrocycle 2c shows three well-anchored quasi-reversible reductions at −0.39, −1.09 and −1.54 V and their corresponding anodic peak current at −0.16, −0.81 and −1.38 V (Figure 6). On the other hand, complex 2b showed a single quasi-reversible redox response of the

• , and this can be attributed to the deposition of macrocycles on the electrode surface. Based on the electrochemical activity of other reported ruthenium complexes, the observed cathodic peaks are roughly assigned to one-electron reductions of the bridged quinonato or diphenyloxamidato ligands, and the

Continuous-flow catalytic asymmetric hydrogenations: Reaction optimization using FTIR inline analysis

• Magnus Rueping,
• Teerawut Bootwicha and
• Erli Sugiono

Beilstein J. Org. Chem. 2012, 8, 300–307, doi:10.3762/bjoc.8.32

• microreactors has been developed. Reaction monitoring was achieved by using an inline ReactIR flow cell, which allows fast and convenient optimization of reaction parameters. The reductions proceeded well, and the desired products were isolated in high yields and with excellent enantioselectivities. Keywords

Synthesis of highly functionalized β-aminocyclopentanecarboxylate stereoisomers by reductive ring opening reaction of isoxazolines

• Melinda Nonn,
• Loránd Kiss,
• Reijo Sillanpää and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2012, 8, 100–106, doi:10.3762/bjoc.8.10

• carbamate side (cis to –NHBoc) of the cyclopentane skeleton. This was confirmed by X-ray analysis of 12. In order to increase the number of multifunctionalized amino ester stereoisomers, we next examined the reductions of isoxazoline-fused cispentacin and transpentacin stereoisomers (3–6) [49]. Reactions

Fluorescent hexaaryl- and hexa-heteroaryl[3]radialenes: Synthesis, structures, and properties

• Antonio Avellaneda,
• Courtney A. Hollis,
• Xin He and
• Christopher J. Sumby

Beilstein J. Org. Chem. 2012, 8, 71–80, doi:10.3762/bjoc.8.7

• been shown to undergo two one-electron reductions to yield the radical anion and dianion species [1]. In this context, in materials science [1][39][40], there is considerable interest in the use of the carbanions obtained by reduction. Up to now, the most electron deficient hexaaryl[3]radialene

• laboratory. Compounds 2 and 3 are electron deficient, 3 noticeably so, and undergo facile reductions to their radical anion and dianion species. We expect that the extension of these compounds in the 3-position will lead to the formation of new cage structures [18] which will utilise the electron deficient

Continuous-flow enantioselective α-aminoxylation of aldehydes catalyzed by a polystyrene-immobilized hydroxyproline

• Xacobe C. Cambeiro,
• Rafael Martín-Rapún,
• Pedro O. Miranda,
• Sonia Sayalero,
• Esther Alza,
• Patricia Llanes and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2011, 7, 1486–1493, doi:10.3762/bjoc.7.172

• limitation is the development of reusable immobilized catalysts, thus allowing important reductions of the “effective” catalyst loading (through recycling and repeated use). Different approaches have been used for the development of immobilized analogs of proline and other organic catalysts. Among them, a

Evaluation of a commercial packed bed flow hydrogenator for reaction screening, optimization, and synthesis

• Marian C. Bryan,
• David Wernick,
• Christopher D. Hein,
• James V. Petersen,
• John W. Eschelbach and
• Elizabeth M. Doherty

Beilstein J. Org. Chem. 2011, 7, 1141–1149, doi:10.3762/bjoc.7.132

• ® systems have been used successfully for a variety of reductions; some of the more notable applications including O-debenzylation, CBz-hydrogenolysis, aromatic ring saturation, imine reduction, and enantioselective carbonyl reductions [8][10][11][12][13]. In our hands, the ThalesNano H-Cube® and the H-Cube

• hydrogenations on the H-Cube®. Surprisingly, to date there have been few reports in the literature characterizing the influence of the H-Cube® system configuration and reaction parameters on the performance and reproducibility. Jones reported consistency in conversion over a series of nitroindole reductions [6

• H-Cube® and the effect of that dispersion on the reaction outcome [15]. As a result of that study, we generated a predictive correlation between non-steady state and continuous flow scale-up conditions for simple reductions. In this report, using the reduction of styrene to ethylbenzene over 10% Pd

Alkene selenenylation: A comprehensive analysis of relative reactivities, stereochemistry and asymmetric induction, and their comparisons with sulfenylation

• Vadim A. Soloshonok and
• Donna J. Nelson

Beilstein J. Org. Chem. 2011, 7, 744–758, doi:10.3762/bjoc.7.85

• (●). These plotted relationships are reasonably linear, demonstrating consistency in rate reductions due to combined steric effects. The total steric effects are greater when R is geminal to another substituent, as expected. The multiple fit lines and the pattern of alkenes within each line clearly indicate

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

Systematic investigations on the reduction of 4-aryl-4-oxoesters to 1-aryl-1,4-butanediols with methanolic sodium borohydride

• Subrata Kumar Chaudhuri,
• Manabendra Saha,
• Amit Saha and
• Sanjay Bhar

Beilstein J. Org. Chem. 2010, 6, 748–755, doi:10.3762/bjoc.6.94

• the keto moiety. Results of a detailed and systematic investigation of the reaction are described. Keywords: diols; esters; lactones; reduction; Introduction Chemoselective reductions of aldehydes, ketones and imines are generally accomplished using NaBH4 in methanol where other reducible functional

EPR and pulsed ENDOR study of intermediates from reactions of aromatic azides with group 13 metal trichlorides

• Giorgio Bencivenni,
• Riccardo Cesari,
• Daniele Nanni,
• Hassane El Mkami and
• John C. Walton

Beilstein J. Org. Chem. 2010, 6, 713–725, doi:10.3762/bjoc.6.84

• ], and δ-azidoesters and chlorides into allylated nitrogen heterocycles [30]. To help in elucidating the mechanisms of these reductions, we used CW EPR spectroscopy and attempted to characterise the reactive intermediates in selected reactions involving gallium trichloride. Surprisingly, we found that

Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine

• Jean Garnier,
• Alan R. Kennedy,
• Leonard E. A. Berlouis,
• Andrew T. Turner and
• John A. Murphy

Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73

• of considerable selectivity in their reductions of organic substrates, and evidence is steadily accumulating to support this. Tetrathiafulvalene (TTF, 1, E11/2 = 0.37 V; E21/2 = 0.67 V in DCM vs SCE) [1], one of the weakest of these donors, reduces arenediazonium salts to aryl radicals [2][3][4][5][6

Synthesis of (3R,5R)-harzialactone A and its (3R,5S)-isomer

• Gowravaram Sabitha,
• Rangavajjula Srinivas,
• Sukant K. Das and
• Jhillu S. Yadav

Beilstein J. Org. Chem. 2010, 6, No. 8, doi:10.3762/bjoc.6.8

• . Epoxide opening with thioacetal and diastereoselective reductions are used as key reactions. Keywords: dithiane; harzialactone A; hydroxyl directed reduction; stereoisomer; Introduction Marine microorganisms such as bacteria, fungi, and microalgae have proved to be a rich source of structurally novel

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• -electron reduction led to formation of the stable hydroquinone, which can be oxidized back to the quinone in the presence of oxygen [48]. Nonetheless, different results were observed in water where both one- and two-electron reductions gave the same DNA adducts. Moreover, the disproportion of the

The development and evaluation of a continuous flow process for the lipase- mediated oxidation of alkenes

• Charlotte Wiles,
• Marcus J. Hammond and
• Paul Watts

Beilstein J. Org. Chem. 2009, 5, No. 27, doi:10.3762/bjoc.5.27

• reagents currently employed, finding use in the synthesis of the aroma linalool oxide and epoxidised soybean oil [16], the reaction times employed for the transformations (< 166 h) and observed reductions in enzyme activity in the presence of H2O2 (2) do not currently make the technique a practical

• crystalline solid. In all cases, the epoxides were synthesised in excellent yield and purity with no hydrolysis products observed. In comparison to the reaction times employed in analogous batch reactions, Table 1, the examples reported herein serve to illustrate the dramatic reductions in reaction time

Synthesis of rigidified flavin–guanidinium ion conjugates and investigation of their photocatalytic properties

• Harald Schmaderer,
• Mouchumi Bhuyan and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 26, doi:10.3762/bjoc.5.26

• benzyl ether cleavage, nitro arene reductions and Diels–Alder reactions. However, no significant gain in photocatalytic performance by the guanidinium ion substrate binding site was observed in comparison to flavins lacking the binding site and the rigid Kemp’s acid skeleton. The primary interaction

Diastereoselective and enantioselective reduction of tetralin- 1,4-dione

• E. Peter Kündig and
• Alvaro Enriquez-Garcia

Beilstein J. Org. Chem. 2008, 4, No. 37, doi:10.3762/bjoc.4.37

• (yields: 76–98%). Fractional crystallization allowed isolation of the cis-diol and the trans-diol (55% and 66% yield, respectively). Borane was used to cleanly give the mono-reduction product. Highly enantioselective CBS reductions afforded the trans-diol (72% yield, 99% ee) and the mono-reduction product

• (81%, 95% ee). Conclusion Diastereoselective and enantioselective reductions of the unexplored tetralin-1,4-dione provides a very convenient entry into a number of synthetically highly attractive 1,4-tetralindiols and 4-hydroxy-1-tetralone. Keywords: asymmetric; catalysis; ketone; reduction; tautomer

• of our studies of reductions of the carbonyl functions in diketone 2. Results and Discussion Diastereoselective bis-reduction of 2 Reduction of tetralin-1,4-dione (2) with a number of reducing agents afforded mixtures of diastereoisomeric cis-diol 6 and trans-diol 7 in the ratios shown in Table 1. It

C₂-symmetric bisamidines: Chiral Brønsted bases catalysing the Diels- Alder reaction of anthrones

• Deniz Akalay,
• Gerd Dürner,
• Jan W. Bats and
• Michael W. Göbel

Beilstein J. Org. Chem. 2008, 4, No. 28, doi:10.3762/bjoc.4.28

• deprotonated by aqueous sodium hydroxide. As an “artefact” of the sequence rule, the S,S configurated diamine 9d leads to bisamidine ent-8d (Scheme 3). The anthrones 1b (R1: H; R2: Cl) and 1c (R1: Cl; R2: H) resulted from regioselective reductions of 1,8-dichloroanthraquinone [10][11]. Aliphatic side chains of

Combining two-directional synthesis and tandem reactions, part 11: second generation syntheses of (±)-hippodamine and (±)-epi-hippodamine

• Annabella F. Newton,
• Martin Rejzek,
• Marie-Lyne Alcaraz and
• Robert A. Stockman

Beilstein J. Org. Chem. 2008, 4, No. 4, doi:10.1186/1860-5397-4-4

• formally derivatives of perhydro-9b-azaphenalene (Figure 1). Another group of natural enemies, parasitic insects, can cause substantial reductions in populations of ladybird species. Recent research [2] has shown that the parasites locate the ladybirds through perception of certain defence alkaloids that

Part 1. Reduction of S-alkyl- thionocarbonates and related compounds in the presence of trialkylboranes/air

• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 45, doi:10.1186/1860-5397-3-45

• % yield. No other identifiable product could be isolated. Zard and Nozaki mentioned similar reductions from α-acylxanthate[19] and α-acyliodide[20][21] respectively. These authors proposed the formation of an intermediate boron enolate that hydrolyses on work-up. A detailed report of our results

Contemporary organosilicon chemistry

• Steve Marsden

Beilstein J. Org. Chem. 2007, 3, No. 4, doi:10.1186/1860-5397-3-4

• -coupling reactions, and the use of silanes as stoichiometric reductants in a range of chemo-, stereo- and enantioselective catalytic reductions. It is therefore a pleasure to serve as Guest Editor for this first "Thematic Series" in the Beilstein Journal of Organic Chemistry, on "Contemporary Organosilicon

Multiple hydride reduction pathways in isoflavonoids

• Auli K. Salakka,
• Tuija H. Jokela and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2006, 2, No. 16, doi:10.1186/1860-5397-2-16

• now reliably available in satisfactory or good yields by hydride reductions to be used as authentic reference compounds in analytical and biological studies. Background The reduction of isoflavones 1 has been actively studied during the last twenty years, owing to the range of interesting biological

• . The discussion is based on the types of reduced isoflavonoid structures formed (Figure 1), i.e., isoflavanones 2, cis-isoflavan-4-ols 3, trans-isoflavan-4-ols 4, the ring opened α-methyldeoxybenzoins 5 and 1,2-diaryl-2-propen-1-ols 6, and isoflavenes 7 and 8 (hydride reductions do not lead to

• cis- and trans-structures for the isoflavanol products and to study their conformational equilibria [32][34]. Borohydride reductions generally give a small preference for the cis products as suggested by Cram's rule [39]. We are not aware of any examples in the literature of single enantiomers of

Methods for the synthesis of polyhydroxylated piperidines by diastereoselective dihydroxylation: Exploitation in the two-directional synthesis of aza-C-linked disaccharide derivatives

• Andrew Kennedy,
• Adam Nelson and
• Alexis Perry

Beilstein J. Org. Chem. 2005, 1, No. 2, doi:10.1186/1860-5397-1-2

• Luche reduction of piperidinones Diastereoselective dihydroxylation of unsaturated piperidines Diagnostic nOe observations for the piperidine 22A Diagnostic nOe observations for the piperidines 22C and 22D Stereoselectivity of two-directional Luche reductions Two-directional functionalisation by