Some mechanistic aspects regarding the Suzuki–Miyaura reaction between selected ortho-substituted phenylboronic acids and 3,4,5-tribromo-2,6-dimethylpyridine

• Piotr Pomarański,
• Piotr Roszkowski,
• Jan K. Maurin,
• Armand Budzianowski and
• Zbigniew Czarnocki

Beilstein J. Org. Chem. 2018, 14, 2384–2393, doi:10.3762/bjoc.14.214

• transformation [22]. In such cases the stereoselectivity may depend on additional chelation effects [28][29][30][31][32][33][34]. Buchwald and co-workers reported an efficient stereoselective synthesis of axially chiral biarylamides by Pd–O bond formation during the oxidative addition step [28][29]. Also other

• less thermodynamically stable isomer, e.g., (syn)-7. In the reaction with ortho-chlorophenylboronic acid, however, the metal chelation is not present and consequently, the thermodynamic product anti-15 is preferentially formed. This observation may be useful in the design of the stereoselective

• synthesis of polyarylated systems. All obtained ortho-methoxy-substituted derivatives of pyridine 2 and 6–9 as well as ortho-chloro-substituted pyridine derivatives 13, 15–17 are chiral molecules and therefore a method for enantiomer discrimination was needed, especially in the case of the planned

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

• ) Red-Al, anh. Et2O, −20 °C, 8 h, 95%; (c) (i) DMSO, CH2Cl2, (COCl)2, −78 °C, (ii) TMS-C≡CH, n-BuLi, THF, −78 °C to rt, 3 h, 89%; (d) K2CO3, MeOH, 0 °C to rt, 1 h, 92%; (e) TBSCl, imidazole, 0 °C to rt, 1 h, 98%; (f) I2, TPP, imidazole, 0 °C to rt, 1 h, 92%. Stereoselective synthesis of (R)-25. Reagents

D-Fructose-based spiro-fused PHOX ligands: synthesis and application in enantioselective allylic alkylation

• Michael R. Imrich,
• Jochen Kraft,
• Cäcilia Maichle-Mössmer and
• Thomas Ziegler

Beilstein J. Org. Chem. 2018, 14, 2082–2089, doi:10.3762/bjoc.14.182

• enantioselectivity [1][2]. Probably the most effective approach in stereoselective synthesis is enantioselective catalysis, because cheap prochiral starting materials can be converted into chiral enantiopure products and no undesirable side products are formed [3][4]. Therefore, the development of new ligands is

• crucial for further progress in stereoselective synthesis [5]. Privileged ligands often used are phosphinooxazoline ligands (PHOX ligands 1, (Figure 1)) which were developed in 1993 independently by Helmchen, Pfaltz and Williams [6][7][8]. Palladium– and iridium–PHOX complexes were already applied as

• efficient catalysts in various asymmetric reactions, for instance allylic substitution and enantioselective hydrogenation [9]. They were also applied in the stereoselective synthesis of complex natural products [10][11][12]. PHOX ligands are nonsymmetrical ligands which can coordinate to a metal center

Recent advances in hypervalent iodine(III)-catalyzed functionalization of alkenes

• Xiang Li,
• Pinhong Chen and
• Guosheng Liu

Beilstein J. Org. Chem. 2018, 14, 1813–1825, doi:10.3762/bjoc.14.154

• high yields [61]. Recently, Jacobsen and co-workers reported the stereoselective synthesis of syn-β-fluoroaziridine building blocks via a chiral aryl iodide-catalyzed fluorination of allylic amines (Scheme 11) [62]. On the basis of their previous work, the C2-symmetric aryl iodide 31 as a catalyst was

Synthesis of spirocyclic scaffolds using hypervalent iodine reagents

• Fateh V. Singh,
• Priyanka B. Kole,
• Saeesh R. Mangaonkar and
• Samata E. Shetgaonkar

Beilstein J. Org. Chem. 2018, 14, 1778–1805, doi:10.3762/bjoc.14.152

• stereoselective synthesis. Additionally, the applications of these reagents in natural product synthesis are also covered. Keywords: hypervalent iodine reagents; iodoarenes; natural products; oxidative cyclization; spirocyclic compounds; Review 1. Introduction The chemistry of spirocyclic compounds is a well

• slow when 10 mol % of additive was used. Once again, iodine(III) species was generated in situ which was probably working as active catalytic species. 2.3. Stereoselective synthesis of spirolactones Recently, Kita and co-workers [78] reported a new type of binaphthyl-based chiral iodine(III) species 38

• ). It was noted that mCPBA/TFA combination did not work well for some transformations and it was replaced with oxidant urea·H2O2 and TFAA as an additive. 3.3. Stereoselective synthesis of spirolactams Gong and co-workers [102] efficiently cyclized 1-hydroxy-N-aryl-2-naphthamides 84 to corresponding

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

• oxidative glycosylation reaction to stereoselectively give C2-acyloxylated β-glycosides in good yields [84] (Scheme 22). Hotha and co-workers utilized the reaction of glycals with hypervalent iodine reagents for the stereoselective synthesis of C2 deoxyglycosides and amino acid glycoconjugates [85]. In

Enantioselective phase-transfer catalyzed alkylation of 1-methyl-7-methoxy-2-tetralone: an effective route to dezocine

• Ruipeng Li,
• Zhenren Liu,
• Liang Chen,
• Jing Pan and
• Weicheng Zhou

Beilstein J. Org. Chem. 2018, 14, 1421–1427, doi:10.3762/bjoc.14.119

• separated by two times of resolution with L-tartaric acid and D-tartaric acid (Scheme 1). Phase-transfer asymmetric catalysis with cinchona alkaloid-derived quaternary ammonium compounds has become one of the topics in stereoselective synthesis in both industry and academia [6][7][8][9]. It was reported [10

Oligonucleotide analogues with cationic backbone linkages

• Melissa Meng and
• Christian Ducho

Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111

• systems, vide supra) as the stereoselective synthesis of stereogenic phosphate derivatives is challenging. Therefore, achiral artificial linkages such as guanidinium groups may be considered advantageous from a stereochemical perspective. For the first synthesis of a pentameric thymidinyl DNG in 1996

Recent advances in synthetic approaches for medicinal chemistry of C-nucleosides

• Kartik Temburnikar and
• Katherine L. Seley-Radtke

Beilstein J. Org. Chem. 2018, 14, 772–785, doi:10.3762/bjoc.14.65

• intermediate. B and C. Functional groups at C2', C3' and C5' stabilize the charged sugar ring and direct the approach of nucleophile to affect the stereochemical outcome of oxocarbenium ion reduction. D. Stereoselective synthesis of protected pseudouridine [80][81]. Synthesis of C1'-substituted 4-aza-7,9

Investigations towards the stereoselective organocatalyzed Michael addition of dimethyl malonate to a racemic nitroalkene: possible route to the 4-methylpregabalin core structure

• Denisa Vargová,
• Rastislav Baran and
• Radovan Šebesta

Beilstein J. Org. Chem. 2018, 14, 553–559, doi:10.3762/bjoc.14.42

• medicines and can be obtained by organocatalytic Michael additions. We show here the stereoselective synthesis of 4-methylpregabalin stereoisomers using a Michael addition of dimethyl malonate to a racemic nitroalkene. The key step of the synthesis operates as a kinetic resolution with a chiral squaramide

• stereoselective synthesis of bioactive compounds [1][2][3]. In particular, stereoselective conversions of nitro compounds served in many syntheses of pharmaceuticals [4]. Derivatives of γ-aminobutyric acid are an important class of medicines targeting problems with the central nervous system, such as pains

Oxidative cycloaddition of hydroxamic acids with dienes or guaiacols mediated by iodine(III) reagents

• Hisato Shimizu,
• Akira Yoshimura,
• Keiichi Noguchi,
• Victor N. Nemykin,
• Viktor V. Zhdankin and
• Akio Saito

Beilstein J. Org. Chem. 2018, 14, 531–536, doi:10.3762/bjoc.14.39

• ) reaction of N-acylnitroso species with dienes provides the facile and highly stereoselective synthesis of 1,2-oxazines, which have been widely recognized as useful synthons in the synthesis of biologically active natural products [1]. Generally, in the presence of dienes, acylnitroso species are in situ

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• the stereoselective synthesis thereof. The intermolecular Wittig reaction of these salts 58 with glyoxylic acid esters gave a dextro or levo γ-aminobutyric acid with values of specific rotation +14° and −6°, respectively, depending on the kind of chiral substituent R1 that was used (Scheme 39) [51]. γ

• -pyrrolocarbaldehyde. Stereoselective synthesis of bicyclic 2-pyrrolidinone derivatives in the reaction of vinylphosphonium halides and 5-acetyl-2-pyrrolidinone. Stereoselective synthesis of 3-pyrroline derivatives in the intramolecular Wittig reaction from vinylphosphonium salts and nitrogen nucleophiles. Synthesis

• vinylphosphonium salts with cyclic diketoester. Synthesis of quinoline derivatives in the intramolecular Wittig reaction from 2-(2-acylphenylamino)vinylphosphonium salts. Stereoselective synthesis of γ-aminobutyric acid in the intermolecular Wittig reaction from chiral 2-aminovinylphosphonium bromides and

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• . This was then converted into a protected amino group employing a Mitsunobu reaction. Finally, removal of the nosyl group, followed by hydrolysis using lithium hydroxide, afforded the targeted isostere 24. Sano and co-workers also worked on the Mg(II)-promoted stereoselective synthesis of (Z

• (Cbz)-ψ[(Z)-CF=CH]-Lys(Cbz) [49] and Fmoc-Orn(Ns)-ψ[(Z)-CF=CH]-Nal were obtained [50]. Fujii and co-workers also worked on the stereoselective synthesis of (E)-monofluoroalkenes (Scheme 17) [51]. To obtain a good selectivity towards the (E)-alkene, they relied on the copper-mediated reduction and the α

• ]-Pro by Sano and co-workers. Synthesis of Cbz-Gly-ψ[(Z)-CF=C]-Pro by Sano and co-workers. Stereoselective synthesis of Fmoc-Gly-ψ[(Z)-CF=CH]-Phe by Pannecoucke and co-workers. Ring-closure metathesis to prepare Gly-ψ[(E)-CF=CH]-Phg by Couve-Bonnaire and co-workers. Stereoselective synthesis of Fmoc-Gly

Homologated amino acids with three vicinal fluorines positioned along the backbone: development of a stereoselective synthesis

• Raju Cheerlavancha,
• Ahmed Ahmed,
• Yun Cheuk Leung,
• Aggie Lawer,
• Qing-Quan Liu,
• Marina Cagnes,
• Hee-Chan Jang,
• Xiang-Guo Hu and
• Luke Hunter

Beilstein J. Org. Chem. 2017, 13, 2316–2325, doi:10.3762/bjoc.13.228

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• -Chlorinations The stereoselective synthesis of chiral α-chlorinated carbonyl compounds is an important topic, since these targets can be valuable intermediates for the synthesis of a variety of different biologically active molecules [85][86]. The main interest in these compounds comes from their versatility

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

A concise and practical stereoselective synthesis of ipragliflozin L-proline

• Shuai Ma,
• Zhenren Liu,
• Jing Pan,
• Shunli Zhang and
• Weicheng Zhou

Beilstein J. Org. Chem. 2017, 13, 1064–1070, doi:10.3762/bjoc.13.105

• 10.3762/bjoc.13.105 Abstract A concise and practical stereoselective synthesis of ipragliflozin L-proline was presented starting from 2-[(5-iodo-2-fluorophenyl)methyl]-1-benzothiophene and 2,3,4,6-tetra-O-pivaloyl-α-D-glucopyranosyl bromide without catalyst via iodine–lithium–zinc exchange. The overall

• yield was 52% in three steps and the product purity was excellent. Two key diastereomers were prepared with efficient and direct access to the α-C-arylglucoside. Keywords: arylzinc derivative; β-C-arylglucoside; diastereomer impurity; ipragliflozin L-proline; stereoselective synthesis; Introduction

• canagliflozin. But so far, it has not been found that this method was applied to synthesize 1. In this paper, we report an efficient and practical method for the preparation of 1 through an arylzinc reagent. Results and Discussion Herein, a concise and practical stereoselective synthesis of 1 with three steps

A strategic approach to [6,6]-bicyclic lactones: application towards the CD fragment of DHβE

• Tue Heesgaard Jepsen,
• Emil Glibstrup,
• François Crestey,
• Anders A. Jensen and
• Jesper Langgaard Kristensen

Beilstein J. Org. Chem. 2017, 13, 988–994, doi:10.3762/bjoc.13.98

• synthetic procedures are extremely scarce. Herein, we wish to provide different strategies used to synthesize the CD fragment of DHβE as a general and simple method for the construction of [6,6]-bicyclic lactones which includes a stereoselective synthesis of vinyl halides, a regio- and stereoselective

• the C ring by an intramolecular Mizoroki–Heck cross-coupling reaction from a Z-configured olefin which would be crucial to the stereochemical outcome of the Heck cyclization event. We envisioned a Z-stereoselective synthesis of a vinyl halide [17] which should secure the desired E-stereochemistry for

Total synthesis of TMG-chitotriomycin based on an automated electrochemical assembly of a disaccharide building block

• Yuta Isoda,
• Norihiko Sasaki,
• Kei Kitamura,
• Shuji Takahashi,
• Sujit Manmode,
• Naoko Takeda-Okuda,
• Jun-ichi Tamura,
• Toshiki Nokami and
• Toshiyuki Itoh

Beilstein J. Org. Chem. 2017, 13, 919–924, doi:10.3762/bjoc.13.93

• afforded TMG-chitotriomycin (1) in 21% yield (10 steps from disaccharide 5bβ) [31]. Conclusion In conclusion, we have achieved the stereoselective synthesis of TMG-chitotriomycin (1) based on the automated electrochemical assembly of disaccharide and monosaccharide building blocks. Thus-obtained

Opportunities and challenges for the sustainable production of structurally complex diterpenoids in recombinant microbial systems

• Katarina Kemper,
• Max Hirte,
• Markus Reinbold,
• Monika Fuchs and
• Thomas Brück

Beilstein J. Org. Chem. 2017, 13, 845–854, doi:10.3762/bjoc.13.85

• - and workup-intensive metal-organic catalysts [13][14][15][16]. The work of McKerrall et al. on ingenol [17][18] sets an example for the difficulty of stereoselective synthesis of complex diterpenes. Additionally, semi-synthetic approaches are tainted with the equivalent issues of economic efficiency

• stereoselective synthesis of (1R,3E,7E,11S,12S)-3,7,18-dolabellatriene, a bicyclic diterpene (Scheme 2). Dollabellanes derive mostly from marine organisms and display bioactivities such as antiviral and cytotoxic effects [59]. Dolabellatriene from a reprogrammed CotB2 contribute with antimicrobial activity

Silyl-protective groups influencing the reactivity and selectivity in glycosylations

• Mikael Bols and
• Christian Marcus Pedersen

Beilstein J. Org. Chem. 2017, 13, 93–105, doi:10.3762/bjoc.13.12

• proposed by Woerpel for these types of reactions [49]. Yamada and collaborators were the first to show that this principle could be used for the stereoselective synthesis of O-glycosides [42]. They prepared thioglucosides 60–62 (Scheme 11) having 2,3,4-O-TIPS groups and either TIPS, benzyl or pivaloyl

Strategies in asymmetric catalysis

• Tehshik P. Yoon

Beilstein J. Org. Chem. 2017, 13, 63–64, doi:10.3762/bjoc.13.8

• reactions. Those of us with research interests in stereoselective synthesis lauded this award because it celebrated the creative insights of these pioneers in asymmetric catalysis and because it marked a general recognition that enantioselective catalysis has had a significant practical impact on the

cis-Diastereoselective synthesis of chroman-fused tetralins as B-ring-modified analogues of brazilin

• Dimpee Gogoi,
• Runjun Devi,
• Pallab Pahari,
• Bipul Sarma and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2016, 12, 2816–2822, doi:10.3762/bjoc.12.280

• [2,1-c]chromen-6a-ols 5 (Figure 1) as B-ring-modified analogues of brazilin through the fusion of chroman and tetralin motifs to generate new bioactive molecules. To the best of our knowledge, the stereoselective synthesis of such chroman-fused tetralins has never been reported. Based on the continuous

• convenient Brønsted acid-catalyzed, metal-free, stereoselective synthesis of 6a,7,8,12b-tetrahydro-6H-naphtho[2,1-c]chromen-6a-ols as B-ring-modified analogues of brazilin using starting materials derived from inexpensive 1-tetralone and phenol derivatives. Our worries concerning the formation cis–trans

Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

• Felicia D’Andrea,
• Giorgio Catelani,
• Lorenzo Guazzelli and
• Venerando Pistarà

Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227

• the stereoselective synthesis of enantiopure inositol derivatives, also the possibility to pick and tag specific positions of the inositol ring, installing the protective groups earlier on the carbohydrate frame through the well-known sugar chemistry, is of extreme interest. Although some attractive