Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• antiemetic in the 1960s. The (S)-enantiomer turned out to be teratogenic. The crucial role of chirality presents a great challenge for synthetic chemists. Asymmetric synthetic methods have emerged and after the development of ample analytical methods over the last few decades, asymmetric synthesis has seen

• for the introduction of chirality to substrates. This review presents a general overview of the synthesis and use of Garner’s aldehyde in natural product synthesis. Particular attention will be paid on the preservation of chiral information in the addition reaction of nucleophiles to the aldehyde

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• was heated in presence of the silver free gold complex 20c a variety of highly substituted azabicyclo[4.2.0]oct-5-enes 84 was obtained in good yields as a single regio- and diastereoisomer. The protocol displayed excellent functional group compatibility and efficient transfer of chirality was observed

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• further optimization, this experiment nicely reveals that chirality installed at the propargylic position in the starting material can be successfully delivered to the cyclization product, as the result of this hydroarylation with concomitant 1,2-iodine shift process. Although this work deals mainly with

• molecular structure of 2f. Synthesis of 3-halo-2H-chromenes. Gram-scale synthesis of 2f. Retaining propargylic chirality. Mechanistic basis postulated for the synthesis of 2. Screening for conditions for the hydroarylation of 4-chlorophenyl (3-iodoprop-2-yn-1-yl) ether. Synthesis of 3-iodo-2H-chromenes

An approach towards azafuranomycin analogs by gold-catalyzed cycloisomerization of allenes: synthesis of (αS,2R)-(2,5-dihydro-1H-pyrrol-2-yl)glycine

• Jörg Erdsack and
• Norbert Krause

Beilstein J. Org. Chem. 2013, 9, 1936–1942, doi:10.3762/bjoc.9.229

• opens an efficient stereoselective access to chiral 2,5-dihydrofurans by axis-to-center chirality transfer (Scheme 1) [21][22][23][24][25][26][27][28][29][30][31][32] and was applied to the total synthesis of various natural products [29][30][31][32][33][34][35][36][37]. Likewise, the corresponding gold

• ; then hydrazine monohydrate) [38][39][62]. Unfortunately, fluoride-mediated desilylation of allene 6c caused complete epimerization of the allenic chirality axis. Therefore, the silylallene was not used in further studies. The results of the gold-catalyzed cycloisomerization of the allenes 7 and 8 to

Stereoselective synthesis of the C79–C97 fragment of symbiodinolide

• Hiroyoshi Takamura,
• Takayuki Fujiwara,
• Isao Kadota and
• Daisuke Uemura

Beilstein J. Org. Chem. 2013, 9, 1931–1935, doi:10.3762/bjoc.9.228

• surface of the acoel flatworm Amphiscolops sp. at 2.5 μmol/L. The entire planar structure of 1 was established by the detailed 2D NMR spectroscopic analysis. However, the complete stereostructural determination of 1 with its 61 chirality centres and a molar mass of 2860 has been an unsolved issue

Enantioselective synthesis of planar chiral ferrocenes via palladium-catalyzed annulation with diarylethynes

• Yan-Chao Shi,
• Rong-Fei Yang,
• De-Wei Gao and
• Shu-Li You

Beilstein J. Org. Chem. 2013, 9, 1891–1896, doi:10.3762/bjoc.9.222

• Road, BDA, Beijing, 100176, China 10.3762/bjoc.9.222 Abstract When Boc-L-Val-OH was used as a ligand for the enantioselective Pd(II)-catalyzed annulation of N,N-substituted aminomethyl ferrocene derivatives with diarylethynes, ferrocenes with planar chirality could be achieved with excellent

• enantioselectivity (up to 99% ee). Keywords: annulation; asymmetric catalysis; C–H activation; ferrocene; palladium; planar chirality; Introduction Chiral ferrocene derivatives have been widely applied to asymmetric catalysis, materials science, biomedical research, etc. [1][2][3][4]. Particularly, ferrocenes with

• planar chirality are applied as efficient ligands or catalysts in asymmetric catalysis [5][6][7][8][9][10][11][12][13][14][15]. However, the typical method for introduction of planar chirality in the ferrrocene backbone is still utilizing the chiral auxiliaries strategy [16][17][18][19][20][21]. Snieckus

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• -epoxides. These novel chiral pyridine N-oxides possess a plane of chirality in a ferrocenyl backbone. The steric hindrance of the Fe(η5-C5Ar5) group on catalysts (Figure 16, OC-78 to OC-80) is very crucial to the enantioselectivities of desymmetrization of meso-epoxides. The increase of steric hindrance of

A reductive coupling strategy towards ripostatin A

• Kristin D. Schleicher and
• Timothy F. Jamison

Beilstein J. Org. Chem. 2013, 9, 1533–1550, doi:10.3762/bjoc.9.175

• well tolerated for the reaction using γ-hydroxy-α,β-enones. Although the presence of chirality at the δ-position allows for diastereoselective intramolecular oxy-Michael addition of hemiacetal-derived alkoxides into α,β-unsaturated esters, the extension of this reaction to ketones was not successful

Homolytic substitution at phosphorus for C–P bond formation in organic synthesis

• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 1269–1277, doi:10.3762/bjoc.9.143

• phosphorus. Plausible mechanism of radical phosphination (Si = (Me3Si)3Si). Stereoselective phosphination leading to (S,S)-aminophosphine derivative. Phosphination with retention of axial chirality. Chemodivergent phosphination. Bis(phosphoryl)-bridged biphenyls by radical phosphination. Bis(phosphoryl

Some aspects of radical chemistry in the assembly of complex molecular architectures

• Béatrice Quiclet-Sire and
• Samir Z. Zard

Beilstein J. Org. Chem. 2013, 9, 557–576, doi:10.3762/bjoc.9.61

• exceedingly potent Claisen rearrangement [37], with the attending advantages of stereocontrol and chirality transfer. Another powerful approach to polycyclic structures is through association with Robinson-type annelations [38]. The synthesis of the precursors also exploits the Claisen rearrangement, as shown

• tricyclic structure 93. In this sequence too, the chirality present in the starting material 89 is initially derived from an allylic alcohol by the Claisen rearrangement and is then transmitted to the other centres. Another powerful reaction that can be associated with the radical chemistry of xanthates is

Chemoenzymatic synthesis and biological evaluation of enantiomerically enriched 1-(β-hydroxypropyl)imidazolium- and triazolium-based ionic liquids

• Paweł Borowiecki,
• Małgorzata Milner-Krawczyk and
• Jan Plenkiewicz

Beilstein J. Org. Chem. 2013, 9, 516–525, doi:10.3762/bjoc.9.56

• on both sides of the chirality center, as shown by the following equations: The signs of these parameters bear the information necessary for the configurational assignment, since they indicate the relative position of L1/L2, with respect to the anisotropic group (phenyl group of MPA). The positive

Development of peptidomimetic ligands of Pro-Leu-Gly-NH₂ as allosteric modulators of the dopamine D₂ receptor

• Swapna Bhagwanth,
• Ram K. Mishra and
• Rodney L. Johnson

Beilstein J. Org. Chem. 2013, 9, 204–214, doi:10.3762/bjoc.9.24

• β-turn that is mimicked is dictated by the chirality of C-3. Lactams 1, 2, 4–6, and 9 (Figure 2) were active in enhancing the binding of the dopamine receptor agonist 2-amino-6,7-dihydroxy-1,2,3,4-tetrahydronaphthalene (ADTN) to dopamine receptors, while 3, 7, and 8 were inactive [19][20]. The

• -lactam constraint restricted the ψ2 torsion angle to 141.9°, i.e., a value close to the 120° seen in an ideal type II β-turn [21], 2 did not exist in a type II β-turn conformation in the crystal state. The same dependence on chirality was seen with δ-lactam analogues 6 and 7. In contrast, in the case of

• the ε-lactam analogues 8 and 9, it is the lactam with the (S)-chirality that possesses the activity. This was expected, as previous studies had shown that the (R)-ε-lactam restricts the ψ2 torsion angle to around −168°, while the (S)-ε-lactam restricts the ψ2 torsion angle to around +168°. This

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

• bond. An intramolecular reaction of the tight ion pair results in migration of the glycosyl moiety from sulfur to nitrogen, which proceeds with complete retention of configuration. As a result, a tight-ion-pair mechanism in which the migrating group retains chirality is suggested (Scheme 2). Aminolysis

A new family of four-ring bent-core nematic liquid crystals with highly polar transverse and end groups

• Kalpana Upadhyaya,
• Venkatesh Gude,
• Golam Mohiuddin and
• Rao V. S. Nandiraju

Beilstein J. Org. Chem. 2013, 9, 26–35, doi:10.3762/bjoc.9.4

• ]. The important properties of these compounds, that is, the ferri- and antiferro-electric phases, chirality and non-linear properties were recently explored [14][15][16][17][18] due to their possible utility in display devices. The majority of these bent-core compounds consist of five-, six- or seven

Design and synthesis of quasi-diastereomeric molecules with unchanging central, regenerating axial and switchable helical chirality via cleavage and formation of Ni(II)–O and Ni(II)–N coordination bonds

• Vadim A. Soloshonok,
• José Luis Aceña,
• Hisanori Ueki and
• Jianlin Han

Beilstein J. Org. Chem. 2012, 8, 1920–1928, doi:10.3762/bjoc.8.223

• , which are able to coordinate to Ni(II) cations leading to quasi-diastereomeric complexes displaying two new elements of chirality: stereogenic axis and helix along with configurational stabilization of the stereogenic center on the nitrogen. Due to the stereocongested structural characteristics of the

• *) and (Ra*,Ph*,Rc*) occurs by intramolecular trans-coordination of Ni–NH and Ni–O bonds providing a basis for a chiral switch model. Keywords: axial chirality; central chirality; chiral switches; coordination bonds; functional materials; helical chirality; modular structural design; molecular devices

• molecules with unchanging central, regenerating axial, and switchable helical chirality, through cleavage/formation of Ni(II)–O and Ni(II)–N coordination bonds. Recently, we introduced a new approach to the design of organic molecules with switchable chirality by simple cleavage and formation of metal

Rh(III)-catalyzed directed C–H bond amidation of ferrocenes with isocyanates

• Satoshi Takebayashi,
• Tsubasa Shizuno,
• Takashi Otani and
• Takanori Shibata

Beilstein J. Org. Chem. 2012, 8, 1844–1848, doi:10.3762/bjoc.8.212

• reactivity. The absolute configuration of planar chirality in 3c was determined to be S by X-ray crystallography (Figure 1). The absolute configuration is consistent with the previous report of diastereoselective ortho-lithiation of 1b [27]. Conclusion In conclusion, a Cp*Rh(III)-catalyzed reaction between

Asymmetric desymmetrization of meso-diols by C₂-symmetric chiral 4-pyrrolidinopyridines

• Hartmut Schedel,
• Keizo Kan,
• Yoshihiro Ueda,
• Kenji Mishiro,
• Keisuke Yoshida,
• Takumi Furuta and
• Takeo Kawabata

Beilstein J. Org. Chem. 2012, 8, 1778–1787, doi:10.3762/bjoc.8.203

• functionality and chirality of catalyst side chains do not affect the absolute configuration of the monoacylate obtained by the asymmetric desymmetrization while they influence the extent of the enantioselectivity. Accordingly, the configuration of the stereocenters in C(2) and C(5) position bearing the amide

Modulating the activity of short arginine-tryptophan containing antibacterial peptides with N-terminal metallocenoyl groups

• H. Bauke Albada,
• Alina-Iulia Chiriac,
• Michaela Wenzel,
• Maya Penkova,
• Julia E. Bandow,
• Hans-Georg Sahl and
• Nils Metzler-Nolte

Beilstein J. Org. Chem. 2012, 8, 1753–1764, doi:10.3762/bjoc.8.200

• observed in their MIC values (Table 3) and within growth inhibition studies (Figure 3). Examples for this difference were found in other systems (see above) and points to a delicate contribution of the chirality of the peptides used. This effect was not observed in the first MIC values determined (Table 2

• of the redox potential on the activity. We assume that the application of model systems will help us to determine the extent in which differences in chirality of the amino acids used to construct the peptides result in more or less favorable interactions. Conclusion We have shown that the replacement

Enantioselective total synthesis of (R)-(−)-complanine

• Krystal A. D. Kamanos and
• Jonathan M. Withey

Beilstein J. Org. Chem. 2012, 8, 1695–1699, doi:10.3762/bjoc.8.192

• asymmetric organocatalytic O-nitrosoaldol reaction as the source of chirality, with accompanying amination of the aldehyde functional group resulting in a concise and efficient synthesis. Results and Discussion Herein we report the concise and efficient synthesis of (R)-(−)-complanine, via a highly effective

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

• Tatyana E. Shubina,
• Matthias Freund,
• Sebastian Schenker,
• Timothy Clark and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

• observed in THF. However, the Michael product was nearly racemic in all runs, indicating that the influence of chirality of the catalyst was minimal in all of the solvents screened. We expected that the resulting ee value would be higher at a lower temperature. However, carrying out the reaction for 24 h

Organocatalytic C–H activation reactions

• Subhas Chandra Pan

Beilstein J. Org. Chem. 2012, 8, 1374–1384, doi:10.3762/bjoc.8.159

• chirality in cationic intermediate C (Scheme 13). Nucleophilic attack then occurred from the same side of the transferred hydrogen to provide (S)-19. The authors concluded that selective activation of one of the enantiotopic hydrogen atoms by chiral phosphoric acid is the main reason for obtaining

Asymmetric one-pot sequential Friedel–Crafts-type alkylation and α-oxyamination catalyzed by a peptide and an enzyme

• Kengo Akagawa,
• Ryota Umezawa and
• Kazuaki Kudo

Beilstein J. Org. Chem. 2012, 8, 1333–1337, doi:10.3762/bjoc.8.152

• of the second-step α-oxyamination was determined mainly by the stereostructure of the peptide catalyst rather than by the chirality of the intermediate 3. Finally, other substrates were tested in the present one-pot sequential reaction system (Table 2). Several substituted indoles gave the products

Cyclodextrin nanosponge-sensitized enantiodifferentiating photoisomerization of cyclooctene and 1,3-cyclooctadiene

• Wenting Liang,
• Cheng Yang,
• Masaki Nishijima,
• Gaku Fukuhara,
• Tadashi Mori,
• Andrea Mele,
• Franca Castiglione,
• Fabrizio Caldera,
• Francesco Trotta and
• Yoshihisa Inoue

Beilstein J. Org. Chem. 2012, 8, 1305–1311, doi:10.3762/bjoc.8.149

• chirality transfer from chiral host to prochiral substrate through the long-lasting intimate supramolecular contacts of guest substrate(s) with the chiral host in both the ground and excited states [4][5][6][7][8][9][10]. Various types of chiral supramolecular hosts, including modified zeolites [11

• unique photochirogenesis behavior significantly different from the conventional sensitizer-modified CDs. Thus, the variation of solution pH and solvent composition enabled us to critically control the stereochemical outcomes, leading to the switching of product chirality and the enhancement of the ee of

Organocatalytic asymmetric allylic amination of Morita–Baylis–Hillman carbonates of isatins

• Hang Zhang,
• Shan-Jun Zhang,
• Qing-Qing Zhou,
• Lin Dong and
• Ying-Chun Chen

Beilstein J. Org. Chem. 2012, 8, 1241–1245, doi:10.3762/bjoc.8.139

• with N-benzyloxycarbonyl and O-benzyl groups [29] was applied in diethyl ether (Table 1, entry 1). Subsequently, an array of tertiary amines derived from quinidine was explored to introduce chirality into the product. While poor enantioselectivity was obtained when β-isocupreidine 1a (β-ICD) or β

Control over molecular motion using the cis–trans photoisomerization of the azo group

• Estíbaliz Merino and
• María Ribagorda

Beilstein J. Org. Chem. 2012, 8, 1071–1090, doi:10.3762/bjoc.8.119

• irradiation of the azobenzene fragment allows the reopening of the azobenzene gate. Unidirectional photoisomerization The process, trans to cis isomerization, generates helicoidal chirality, such that the isomer can adopt a helicoidal geometry with P or M chirality. The configurational stability of cis