Multicomponent reactions (MCRs): a useful access to the synthesis of benzo-fused γ-lactams

• Edorta Martínez de Marigorta,
• Jesús M. de Los Santos,
• Ana M. Ochoa de Retana,
• Javier Vicario and
• Francisco Palacios

Beilstein J. Org. Chem. 2019, 15, 1065–1085, doi:10.3762/bjoc.15.104

• . This is a good partner for a cycloaddition with an imine such as 99 that would give rise to the spiro β- and γ-lactam derivative 101 in a diastereoselective manner. Indeed, a seminal contribution also made use of a similar Pd-catalysed carbonylation followed by amide formation and cyclization in a

Stereo- and regioselective hydroboration of 1-exo-methylene pyranoses: discovery of aryltriazolylmethyl C-galactopyranosides as selective galectin-1 inhibitors

• Alexander Dahlqvist,
• Axel Furevi,
• Niklas Warlin,
• Hakon Leffler and
• Ulf J. Nilsson

Beilstein J. Org. Chem. 2019, 15, 1046–1060, doi:10.3762/bjoc.15.102

• using a highly diastereoselective hydroboration of C1-exo-methylene pyranosides giving inhibitors with fourfold or better selectivity for galectin-1 over galectin-3, -4C (C-terminal CRD), -4N (N-terminal CRD), -7, -8C, -8N, -9C, and -9N and dissociation constants down to 170 µM. Keywords: C-galactoside

• synthesis pathway involving a diastereoselective hydroboration towards (aryltriazolyl)methyl galactopyranosyl derivatives and determined the viability of this as a scaffold for galectin inhibitors by screening a library of fourteen different products against galectins -1, -3, -4C (C-terminal CRD), -4N (N

An efficient synthesis of the guaiane sesquiterpene (−)-isoguaiene by domino metathesis

• Yuzhou Wang,
• Ahmed F. Darweesh,
• Patrick Zimdars and
• Peter Metz

Beilstein J. Org. Chem. 2019, 15, 858–862, doi:10.3762/bjoc.15.83

• (−)-Isoguaiene was prepared from (S)-citronellal in only 9–10 steps with good overall yields. Either a trienyne or a dienediyne metathesis and highly diastereoselective organocatalytic Michael additions of aldehydes derived from (S)-citronellal served as the key transformations. Keywords: domino reactions

• sesquiterpene (−)-isoguaiene (1) using either a trienyne or a dienediyne metathesis and highly diastereoselective organocatalytic Michael additions of aldehydes derived from 5 as the key steps. Structures of the sesquiterpene (−)-isoguaiene (1) and the trisnorsesquiterpene clavukerin A (2). Retrosynthetic

A diastereoselective approach to axially chiral biaryls via electrochemically enabled cyclization cascade

• Hong Yan,
• Zhong-Yi Mao,
• Zhong-Wei Hou,
• Jinshuai Song and
• Hai-Chao Xu

Beilstein J. Org. Chem. 2019, 15, 795–800, doi:10.3762/bjoc.15.76

• Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, People’s Republic of China 10.3762/bjoc.15.76 Abstract A diastereoselective approach to axially chiral imidazopyridine-containing biaryls has been developed. The reactions proceed through a radical cyclization cascade to construct

• diastereoselective approach for the synthesis of axially chiral biaryls through an electricity-powered cyclization cascade. The reactions employ easily assembled starting materials and afford functionalized imidazopyridine-based biaryls in good to high yields and diastereoselectivity. Reaction design. Scope of

Stereochemical investigations on the biosynthesis of achiral (Z)-γ-bisabolene in Cryptosporangium arvum

• Jan Rinkel and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2019, 15, 789–794, doi:10.3762/bjoc.15.75

• and was reported from different sources such as the liverwort Dumortiera hirsuta [19]. Its (Z)-configured exocyclic double bond has also attracted the attention of synthetic chemistry for a diastereoselective total synthesis [20][21][22]. The wide occurrence of 5 is likely connected to the simple

Diastereo- and enantioselective preparation of cyclopropanol derivatives

• Marwan Simaan and
• Ilan Marek

Beilstein J. Org. Chem. 2019, 15, 752–760, doi:10.3762/bjoc.15.71

• Marwan Simaan Ilan Marek The Mallat Family Laboratory of Organic Chemistry, Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa, 32000, Israel 10.3762/bjoc.15.71 Abstract The diastereoselective carbocupration reaction of alkoxy-functionalized cyclopropene derivatives

• ). First, we checked that the carbometalation reaction was regio- and diastereoselective by addition of lower order cyanocuprate, easily obtained from the corresponding organolithium and a stoichiometric amount of CuCN (Scheme 4) [68][69][70]. The addition reaction proceeds similarly for the addition of

• when the same sequence of diastereoselective carbometalation/oxidation was performed on cyclopropenyl ester 1, the in situ-formed donor–acceptor cyclopropanol undergoes a selective ring-opening to provide the acyclic product possessing a quaternary carbon stereocenter [57]. As the enantioselective

A chemoenzymatic synthesis of ceramide trafficking inhibitor HPA-12

• Seema V. Kanojia,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2019, 15, 490–496, doi:10.3762/bjoc.15.42

• synthesis of the title compound has been developed using an efficient and highly enantioselective lipase-catalyzed acylation in a hydrophobic ionic liquid, [bmim][PF6], followed by a diastereoselective asymmetric dihydroxylation as the key steps for incorporating the stereogenic centers. The further

• (1R,3S)-HPA-12 (2) used the chiral pool approach [15][16], crystallization-induced asymmetric transformation [17], diastereoselective reduction of γ-aryl-γ-oxo-β-amino alcohol [18], cycloaddition of oxime with alkenes [19], enantioselective carbonyl reduction followed by an organocatalyzed α-amination

• /aza-Michael reaction of 3,6-dihydro-1,2-dioxines followed by diastereoselective reduction [25]. Most of these methods employ starting materials or catalysts, which are not commercially available, and also require operationally demanding reaction conditions. Hence a need to develop a simple, efficient

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• (Scheme 1, reaction 3) [23][26][27][28][29][30][31][32][33]. Thus, methylenecyclopropanes have been prepared by diastereoselective addition of Grignard reagents to cyclopropenylmethyl ethers, possessing a hydroxymethyl directing substituent at C3, in the absence or in the presence of a catalyst (copper or

• previously with alkylidene(aminocyclopropane) derivatives, diastereoselective hydrogenation reactions of alkylidenecyclopropanes possessing a single substituent at C2 can be carried out with complementary face selectivities, depending on the conditions and substrates. Thus, the hydrogenation of 58a catalyzed

• out in the presence of Crabtree’s catalyst [58], thereby allowing access to cyclopropylcarbinol 73’ with high diastereoselectivity (73’/73 = 97:3, Scheme 25). By taking advantage of the directing effect of a hydroxy group, diastereoselective hydrogenations of alkylidenecyclopropanes possessing two

Ruthenium-based olefin metathesis catalysts with monodentate unsymmetrical NHC ligands

• Veronica Paradiso,
• Chiara Costabile and
• Fabia Grisi

Beilstein J. Org. Chem. 2018, 14, 3122–3149, doi:10.3762/bjoc.14.292

• 24b showed activities similar to that of GII-SIMes. They also exhibited different E/Z selectivities in CM transformations (e.g., Table 1, entry 2), and gave improved selectivities in a diastereoselective RCM reaction (Table 1, entry 3). Ledoux, Verpoort et al. described a series of phosphine

• diastereoselective ring-rearrangement metathesis (dRRM) of cyclopentene 131 (Scheme 12). The presence of a nitro group at the ortho or para positions of the benzyl substituent (134 and 135 in Figure 24), reported by Malinowska and co-workers [45], led to higher activities in the RCM of 7 and 9 (Schemes 1 and 2

Stereodivergent approach in the protected glycal synthesis of L-vancosamine, L-saccharosamine, L-daunosamine and L-ristosamine involving a ring-closing metathesis step

• Pierre-Antoine Nocquet,
• Aurélie Macé,
• Frédéric Legros,
• Jacques Lebreton,
• Gilles Dujardin,
• Sylvain Collet,
• Arnaud Martel,
• Bertrand Carboni and
• François Carreaux

Beilstein J. Org. Chem. 2018, 14, 2949–2955, doi:10.3762/bjoc.14.274

• vinyl ethers as key step of reaction sequences developed. Keywords: 3-amino glycals; diastereoselective additions to aldehydes; pluramycins; ring-closing metathesis; vinyl ethers; Introduction Several classes of medicinally useful molecules with antibiotic and anticancer activity contain in their

• corresponding alkenes 13a,b in 90% and 63% yield, respectively, over two steps. Alternatively, we envisioned that, from the same α-substituted chiral aldehyde 5, compound 13b could be obtained in a more straightforward manner employing a strategy based on a diastereoselective allylboration reaction (Scheme 2

• metathesis of vinyl ethers as key step for the preparation of several carbamate-protected 3-aminoglycals. Evans aldol reaction for the preparation of diastereomeric compounds 13a and 13b. Alternative preparation of 13b based on a diastereoselective allylboration. O-Vinylation-ring-closing metathesis sequence

Green synthesis of new chiral 1-(arylamino)imidazo[2,1-a]isoindole-2,5-diones from the corresponding α-amino acid arylhydrazides in aqueous medium

• Nadia Bouzayani,
• Jamil Kraїem,
• Sylvain Marque,
• Yakdhane Kacem,
• Abel Carlin-Sinclair,
• Jérôme Marrot and
• Béchir Ben Hassine

Beilstein J. Org. Chem. 2018, 14, 2923–2930, doi:10.3762/bjoc.14.271

• . The reaction is totally diastereoselective and gives access to the nitrogenated tricyclic core with a relative trans stereochemistry. Keywords: sodium dodecyl sulfate; totally diastereoselective; trans-stereochemistry; Introduction Tricyclic compounds, such as imidazo[2,1-a]isoindol-5-ones, are

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• The first synthesis of diterpenoid eunicellane skeletons incorporating a 1,3-cyclohexadiene moiety is presented. Key step is a low-valent titanium-induced pinacol cyclization that proved to be perfectly diastereoselective. Determination of the relative configuration of the diol was aided by the

Microfluidic light-driven synthesis of tetracyclic molecular architectures

• Javier Mateos,
• Nicholas Meneghini,
• Marcella Bonchio,
• Nadia Marino,
• Tommaso Carofiglio,
• Xavier Companyó and
• Luca Dell’Amico

Beilstein J. Org. Chem. 2018, 14, 2418–2424, doi:10.3762/bjoc.14.219

• synthetic method for the direct assembly of highly functionalized tetracyclic pharmacophoric cores. Coumarins and chromones undergo diastereoselective [4 + 2] cycloaddition reactions with light-generated photoenol intermediates. The reactions occur by aid of a microfluidic photoreactor (MFP) in high yield

• anticipated that the successful development of these photoreactions would generate valuable privileged scaffolds, namely, naphthochromenones 4 and benzoxanthenes 5, through a diastereoselective light-driven [4 + 2] cycloaddition reaction. Interestingly, the tetracyclic scaffolds 4 and 5 are embodied in

• different biologically active molecules, with diverse pharmacological activities [9]. To the best of our knowledge, diastereoselective methods for the direct construction of naphthochromenone 4 are still missing. On the other hand, the reported construction of the benzoxanthene scaffold 5 relies on the use

A novel and practical asymmetric synthesis of eptazocine hydrobromide

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

Beilstein J. Org. Chem. 2018, 14, 2340–2347, doi:10.3762/bjoc.14.209

• the unwanted isomer [3][4][5][6]. Other asymmetric syntheses of 1 have been reported in the literature. These relied either on organometallic catalysis [7], asymmetric tandem addition to chiral tetrahydronaphthalenes [8], bioenzymatic steps [9] or diastereoselective Evans alkylation from oxazolidinone

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• forms cobalt enolate J2, which converts into J3 by the addition of aldehyde via a chair transition state in a diastereoselective manner. Finally, protonolysis affords product 62 and regenerates the active Co(III)Cp* catalyst for the next cycle. Later, Li et al. reported a Co(III)-catalyzed

Synthesis of 1,4-imino-L-lyxitols modified at C-5 and their evaluation as inhibitors of GH38 α-mannosidases

• Maroš Bella,
• Sergej Šesták,
• Ján Moncoľ,
• Miroslav Koóš and
• Monika Poláková

Beilstein J. Org. Chem. 2018, 14, 2156–2162, doi:10.3762/bjoc.14.189

• chromatography on silica gel, the sensitive aldehyde 17 was used in the next step without further purification and characterization. Diastereoselective addition of MeMgBr to the aldehyde group of 17 gave alcohol 18 as single diastereoisomer in 69% yield. Removal of the Cbz protecting group of 18 under catalytic

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• protected naturally occurring amines such as GABA and phenylethylamine as well as diamines with orthogonal protecting groups, cf. product 2c. The combination of this protocol with the diastereoselective reductive amination reported by Hughes and Devine [41], provides access to very high value chiral α

• trifluoromethyl are not tolerated. No functional group tolerance towards other carbonyls such as esters or aldehydes is demonstrated. The use of terminal or trisubstituted alkenes is limited and the reaction times are long. However, the authors do report that the reaction is somewhat diastereoselective, favouring

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

• diastereoselective catalytic fluorination was developed by the same group (Scheme 14, bottom) [65] using the lactate-based resorcinol derivative 44 as the catalyst. By this route chiral 4-fluoroisochromanones 46 could be accomplished in high enantio- and diastereoselectivity. The same I(III) intermediate 47 was

• addition, electron-rich aromatics present in the substrates were also brominated. During the screening of the iodoarene pre-catalysts, a dihalogenation product was detected in the presence of iodoarenes bearing electron-donating side chains 70. A diastereoselective dihalogenation method was established

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

• derivative, 2-dimethoxybenzoate 20 was prepared from tribenzylated ribose 16. Introduction of a dimethoxybenzoyl (DMBz) group at the 2-position and diastereoselective formation of sulfoxide 20, favored in Pummerer-type glycosylation reactions and cases where the approach of the nucleophile is restricted

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• iodides, allenes, and aldehydes has been developed to afford multi-substituted homoallylic alcohols in a diastereoselective manner. Control experiments for understanding the reaction mechanism reveal that the cobalt catalyst is involved in the oxidative addition and carbometalation steps in the reaction

• , whereas the chromium salt generates highly nucleophilic allylchromium intermediates from allylcobalt species, without the loss of stereochemical information, to allow the addition to aldehydes. Keywords: chromium; cobalt; diastereoselective; homoallyl alcohols; hybrid catalyst; three-component coupling

• three-component coupling method is herein reported for the direct synthesis of highly diastereoselective multi-substituted homoallyl alcohols employing a cobalt/chromium hybrid catalyst (Scheme 5). Results and Discussion Initially, suitable reaction conditions were investigated for the three-component

Recent applications of chiral calixarenes in asymmetric catalysis

• Mustafa Durmaz,
• Erkan Halay and
• Selahattin Bozkurt

Beilstein J. Org. Chem. 2018, 14, 1389–1412, doi:10.3762/bjoc.14.117

• to synthesize inherently chiral calixarenes 36 and 37 [43][44]. In a continuation of their previous studies, they have reported diastereoselective synthesis of inherently chiral calixarene derivatives 38 and 39 via chiral tert-butyloxazoline-directed lithiation (Figure 4) [45]. It has been shown that

Stereoselective nucleophilic addition reactions to cyclic N-acyliminium ions using the indirect cation pool method: Elucidation of stereoselectivity by spectroscopic conformational analysis and DFT calculations

• Koichi Mitsudo,
• Junya Yamamoto,
• Tomoya Akagi,
• Atsuhiro Yamashita,
• Masahiro Haisa,
• Kazuki Yoshioka,
• Hiroki Mandai,
• Koji Ueoka,
• Christian Hempel,
• Jun-ichi Yoshida and
• Seiji Suga

Beilstein J. Org. Chem. 2018, 14, 1192–1202, doi:10.3762/bjoc.14.100

• give the disubstituted piperidine derivatives in an excellent diastereoselective manner (Scheme 1). This result inspired us to investigate the stereochemistry of the N-acyliminium ions by means of NMR spectroscopy, which is challenging to achieve without using cation pool methods. The current report

• presents the diastereoselective synthesis of disubstituted piperidine derivatives by the indirect cation pool method and the elucidation of the stereoselectivity based on both NMR analyses of the cyclic N-acyliminium ions and DFT calculations. Results and Discussion N-Acyliminium ions obtained from N-Boc

• form product, because an attack from another side would lead to a more unstable product with a twist form [13]. As a close study, Woerpel reported a diastereoselective substitution reaction for synthesizing disubstituted tetrahydropyrans via six-membered oxocarbenium ions generated in situ from

Fluorocyclisation via I(I)/I(III) catalysis: a concise route to fluorinated oxazolines

• Felix Scheidt,
• Christian Thiehoff,
• Gülay Yilmaz,
• Stephanie Meyer,
• Constantin G. Daniliuc,
• Gerald Kehr and
• Ryan Gilmour

Beilstein J. Org. Chem. 2018, 14, 1021–1027, doi:10.3762/bjoc.14.88

• diastereoselective on account of the proximal nature of the stereocentre (65%, dr >95:5). Compound 3 is noteworthy on account of the β-amino alcohol and β-fluoro alcohol motifs that collectively preorganised the propyl chain. Stabilising hyperconjugative interactions manifest themselves in the characteristic gauche

Diastereoselective auxiliary- and catalyst-controlled intramolecular aza-Michael reaction for the elaboration of enantioenriched 3-substituted isoindolinones. Application to the synthesis of a new pazinaclone analogue

• Romain Sallio,
• Stéphane Lebrun,
• Frédéric Capet,
• Francine Agbossou-Niedercorn,
• Christophe Michon and
• Eric Deniau

Beilstein J. Org. Chem. 2018, 14, 593–602, doi:10.3762/bjoc.14.46

• stereocenter [14]. Hence, the asymmetric synthesis of functionalized 3-substituted isoindolinones using short, versatile and selective procedures is clearly a topic of current interest. Two strategies can be applied for the asymmetric synthesis of 3-substituted isoindolinones. First, diastereoselective

• and 8 in 61–75% isolated yields after work-up (Scheme 2, Figure 3). Diastereoselective intramolecular aza-Michael reaction First, the study of the diastereoselective intramolecular aza-Michael reaction of benzamide substrate (S)-6a allowed us to optimize the reaction conditions (Table 1) and latter to

• 3:7). Removal of the chiral auxiliary. Synthesis of isoindolinones 1a–c, 1e, 2; isolated yield, ee by HPLC. Synthesis of pazinaclone analogue (3S)-27. Identification of the optimum reaction conditions for the diastereoselective intramolecular aza-Michael reaction of (S)-6a. Identification of the

The selective electrochemical fluorination of S-alkyl benzothioate and its derivatives

• Shunsuke Kuribayashi,
• Tomoyuki Kurioka,
• Shinsuke Inagi,
• Ho-Jung Lu,
• Biing-Jiun Uang and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2018, 14, 389–396, doi:10.3762/bjoc.14.27

• be the most suitable combination as electrolytic solvent and supporting salt as well as fluorine source for the anodic fluorination. The electrochemical fluorination of cyclic benzothioates such as benzothiophenone was also achieved. Keywords: anodic cyclization; diastereoselective fluorination