C–H-Functionalization logic guides the synthesis of a carbacyclopamine analog

• Sebastian Rabe,
• Johann Moschner,
• Marina Bantzi,
• Philipp Heretsch and
• Athanassios Giannis

Beilstein J. Org. Chem. 2014, 10, 1564–1569, doi:10.3762/bjoc.10.161

• intermediate in the synthesis of 2 (see Scheme 1). We envisioned a rhodium-catalyzed C–H-insertion into the C17–H bond to occur with a high degree of selectivity (both regio- and stereoselectivity) to form the all-carbon E-ring (for its structure see 11, Scheme 2). Furthermore, a Wagner–Meerwein rearrangement

Stereocontrolled synthesis of 5-azaspiro[2.3]hexane derivatives as conformationally “frozen” analogues of L-glutamic acid

• Beatrice Bechi,
• David Amantini,
• Cristina Tintori,
• Maurizio Botta and
• Romano di Fabio

Beilstein J. Org. Chem. 2014, 10, 1114–1120, doi:10.3762/bjoc.10.110

• rotation around the C3–C4 bond present in the azetidine derivative Ia by incorporating an appropriate spiro moiety. The cyclopropyl moiety was introduced by a diastereoselective rhodium catalyzed cyclopropanation reaction. Keywords: Amino acids; carbenes; cyclopropanation; rhodium; spiro compounds

• exploration of the reactivity of the terminal olefin towards the key cyclopropanation step performed in the presence of ethyl diazoacetate and Rh2(OAc)4 (rhodium acetate dimer). The reaction was carefully studied in different solvents (i.e., CH2Cl2, DCE, toluene) and with variable amounts of both ethyl

• from D-serine, their synthesis was accomplished in 10 steps in good overall yield. After an extensive investigation on the best synthetic approach, key intermediate 20 was successfully prepared by an efficient rhodium-catalyzed cyclopropanation of a terminal double bond of compound 18 with ethyl

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• ][94][95][96], palladium [97][98][99] or nickel [100][101][102][103][104] complexes. Other catalysts that have been less investigated are iron [105][106][107], rhodium [108][109][110], lanthanides [111][112][113][114], copper [115] and alkaline-earth metals [114][116]. The catalyst activates either the

• were isolated as their thiophosphine analogues 135 and 136. Hayashi and co-workers have reported a rhodium-catalyzed phosphination of alkynes 134b using silylphosphines 137 as phosphinating agents (Table 15) [108]. The cationic rhodium catalyst was generated in situ by adding silver triflate to a

Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

• Zong Guan,
• Jan C. Namyslo,
• Martin H. H. Drafz,
• Martin Nieger and
• Andreas Schmidt

Beilstein J. Org. Chem. 2014, 10, 832–840, doi:10.3762/bjoc.10.79

• . Virtasen aukio 1), FIN-00014 University of Helsinki, Finland 10.3762/bjoc.10.79 Abstract Deprotonation of indazolium salts at low temperatures gives N-heterocyclic carbenes of indazoles (indazol-3-ylidenes) which can be trapped as rhodium complexes (X-ray analysis). In the absence of Rh, the indazol-3

• available by copper-catalyzed aryl couplings or Buchwald–Hartwig reactions [22]. Pyrazol-3-ylidenes rearrange similarly to quinolines [17]. We report here on two unexpected rearrangements of indazol-3-ylidene, and trapping reactions of the N-heterocyclic carbene with rhodium. Results and Discussion On

• betaines by inter- or intramolecular cycloadditions are typical reactions [18][19]. To prove the initial formation of an N-heterocyclic carbene in this reaction we tried trapping reactions starting from 12a and 12e with carbonylbis(triphenylphosphine)rhodium(I) chloride under otherwise unchanged reaction

Phosphinate-containing heterocycles: A mini-review

• Olivier Berger and
• Jean-Luc Montchamp

Beilstein J. Org. Chem. 2014, 10, 732–740, doi:10.3762/bjoc.10.67

• LiHMDS (Scheme 5) [19]. Tanaka and coworkers have synthesized chiral benzopyrano and naphthopyrano-fused helical phosphafluorenes 14a–d from dialkynyl phosphinate 12 and phenol-linked terminal tetrayne 13 at room temperature for only 1 h using a cationic rhodium(I)/(R)-tol-BINAP complex as a catalyst

• -Dieckmann condensation. Palladium-catalyzed oxidative arylation. Tandem cross-coupling/Dieckmann condensation. Rhodium-catalyzed double [2 + 2 + 2] cycloaddition. Silver oxide-mediated alkyne–arene annulation. Silver acetate-mediated alkyne–arene annulation. Cyclization through phosphinylation/alkylation of

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• substituted 1,2-dihydroisoquinolines 40 characterized by the presence of an α-hydroxy/alkoxy-α-carboxylate carbon pendant. The oxonium ylide 39 was prepared by a well-known procedure involving a rhodium carbenoid intermediate, generated in situ from the corresponding diazoacetate 37 under Rh2(OAc)4 catalysis

Boron-substituted 1,3-dienes and heterodienes as key elements in multicomponent processes

• Ludovic Eberlin,
• Fabien Tripoteau,
• François Carreaux,
• Andrew Whiting and
• Bertrand Carboni

Beilstein J. Org. Chem. 2014, 10, 237–250, doi:10.3762/bjoc.10.19

• and co-workers described metal-catalysed tandem Diels–Alder/hydrolysis reactions of 2-boron-substituted 1,3-dienes [54][55]. Boron-dienes containing various ligands reacted with maleimides in the presence of rhodium and copper catalysts using BINAP as ligand (Scheme 15). NMR analysis of the crude

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• 82. Diazotransfer using p-ABSA [86] yielded diazoester 83. Selective rhodium-catalyzed cyclopropanation of the cis-double bond [87][88] of diene 84 [89] furnished cis-divinylcyclopropane 85, which underwent DVCPR upon Kugelrohr distillation at 140 °C to give bicyclic 86. Selective hydrogenation of

• detected in the human body after cocaine consumption. It can be degradatively accessed from cocaine through pyrolysis, cocaine congeners can be prepared via conjugate addition afterwards [113][114]. Boc-protected pyrrole 127 was subjected to rhodium-catalyzed cyclopropanation with vinyldiazo compound 128

• . Removal of the MOM-protecting group followed by reduction of the amide concluded Fukuyama’s total synthesis of gelsemine (146). An approach similar to Davies formal [4 + 3]-cycloaddition [81] was used by the group of Kende [130] to access the alkaloid isostemofoline (158, see Scheme 19) [131]. Rhodium

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• ) is hydrogenated to the vinylogous carbamate 2.53 in the presence of acetic anhydride. Then the intermediate 2.53 can be subjected to an asymmetric hydrogenation utilising rhodium-based catalyst systems at elevated hydrogen pressures rendering the desired ethyl (R)-nipecotate 2.54 [75]. Uniting the

Simple and rapid hydrogenation of p-nitrophenol with aqueous formic acid in catalytic flow reactors

• Rahat Javaid,
• Shin-ichiro Kawasaki,
• Akira Suzuki and
• Toshishige M. Suzuki

Beilstein J. Org. Chem. 2013, 9, 1156–1163, doi:10.3762/bjoc.9.129

• thin (1–2 μm) palladium (Pd), platinum (Pt), and rhodium (Rh) layers by an electroless plating procedure [10][11]. These tubular reactors combined the merit of flow reaction processing with the catalytic properties of various metals. Unlike packed-bed catalysts, hollow tubular reactors can minimize the

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• ][51][52][53] or enolates [54] from simple alkynes by carbocupration reactions. Not only copper but also rhodium can catalyze carbometalation reactions. Hayashi applied carborhodation chemistry [55][56][57][58] to the reactions of aryl alkynyl ketones with arylzinc reagents, which provided enolates of

• indanones (Scheme 4) [59]. Phenylrhodation of 1g first proceeds to form 1A. A subsequent intramolecular 1,4-hydrogen shift gives 1B, which smoothly undergoes an intramolecular 1,4-addition to yield 1C. Finally, transmetalation from the phenylzinc reagent to rhodium enolate 1C affords zinc enolate 1h, which

• directing group to control the regioselectivity to afford 2E (Scheme 13, path B) [25][74][75][76]. In 2009, Lam reported the rhodium-catalyzed carbozincation of ynamides. The reaction smoothly proceeded under mild conditions to provide the corresponding intermediate 2i regioselectively (Scheme 14) [77][78

Alkyne hydroarylation with Au N-heterocyclic carbene catalysts

• Cristina Tubaro,
• Marco Baron,
• Andrea Biffis and
• Marino Basato

Beilstein J. Org. Chem. 2013, 9, 246–253, doi:10.3762/bjoc.9.29

• ], gold [18][19], or rhodium [20], as well as of non-noble, electrophilic metals [21][22][23][24][25][26] have also been successfully employed. Finally, an even greater number of catalysts have been proposed over the years to promote alkyne hydroarylation in an intramolecular fashion [1][2][3][4][5][6][7

Iron-containing mesoporous aluminosilicate catalyzed direct alkenylation of phenols: Facile synthesis of 1,1-diarylalkenes

• Satyajit Haldar and
• Subratanath Koner

Beilstein J. Org. Chem. 2013, 9, 49–55, doi:10.3762/bjoc.9.6

• ][23]. In general, the reaction shows β-selectivity, and there are only a few reports available concerned with α-substituted products [24][25][26]. Sabarre and Love reported a one-pot rhodium-catalyzed alkyne hydrothiolation followed by a nickel-catalyzed Kumada-type cross coupling with Grignard

Flow photochemistry: Old light through new windows

• Jonathan P. Knowles,
• Luke D. Elliott and
• Kevin I. Booker-Milburn

Beilstein J. Org. Chem. 2012, 8, 2025–2052, doi:10.3762/bjoc.8.229

• , thus, gave data ideally suited to mechanistic studies [56]. The potential of microreactors in the photocatalytic splitting of water has also come under investigation. In this case a rhodium-containing inorganic photocatalyst was employed, and again online QMS permitted mechanistic studies to be

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

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

• ; ferrocene; rhodium; Introduction Ferrocene and its derivatives are among the most useful organometallic compounds because of their chemical and thermal stabilities, structures, and redox activity [1][2]. One of the most remarkable applications of ferrocene derivatives is as chiral ligands [3][4]. A variety

Evaluation of a chiral cubane-based Schiff base ligand in asymmetric catalysis reactions

• Kyle F. Biegasiewicz,
• Michelle L. Ingalsbe,
• Jeffrey D. St. Denis,
• James L. Gleason,
• Junming Ho,
• Michelle L. Coote,
• G. Paul Savage and
• Ronny Priefer

Beilstein J. Org. Chem. 2012, 8, 1814–1818, doi:10.3762/bjoc.8.207

• (MAO) inactivators [8][9][10]. Cubanes have also shown a propensity to undergo cage opening. In particular, syn-tricyclooctadienes are formed when rhodium(I) salts are introduced [11], while with silver(I) or palladium(II) catalysts, cuneane is obtained [12]. Spontaneous cage opening has been observed

Copper-catalyzed CuAAC/intramolecular C–H arylation sequence: Synthesis of annulated 1,2,3-triazoles

• Rajkumar Jeyachandran,
• Harish Kumar Potukuchi and
• Lutz Ackermann

Beilstein J. Org. Chem. 2012, 8, 1771–1777, doi:10.3762/bjoc.8.202

• ][16]. This streamlining of organic synthesis has predominantly been accomplished with palladium [4][5][6][7][8][9][10][11][12][13][14][15][16], rhodium [17][18][19] or ruthenium [20][21][22] complexes [4][5][6][7][8][9][10][11][12][13][14][15][16]. However, less expensive nickel, cobalt, iron or

C2-Alkylation of N-pyrimidylindole with vinylsilane via cobalt-catalyzed C–H bond activation

• Zhenhua Ding and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2012, 8, 1536–1542, doi:10.3762/bjoc.8.174

• as a directing group for rhodium-catalyzed C2-alkenylation [36], was entirely ineffective. Vinylsilanes bearing dimethylphenylsilyl and triphenylsilyl groups were amenable to the addition reaction with 1a, affording the adduct 3ab and 3ac in modest yields. Vinyltriethoxysilane also reacted with 1a in

N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters

• Takuya Uno,
• Yusuke Kobayashi and
• Yoshiji Takemoto

Beilstein J. Org. Chem. 2012, 8, 1499–1504, doi:10.3762/bjoc.8.169

• migration of the N-acyl glycine derivatives [18]. The other consists of C–N bond-forming reactions, such as (c) a rhodium-catalyzed N–H insertion reaction with α-diazo-β-keto esters [19][20][21], and (d) α-oxidation of β-keto esters to the corresponding oximes and the subsequent hydrogenation [22]. However

Impact of cyclodextrins on the behavior of amphiphilic ligands in aqueous organometallic catalysis

• Hervé Bricout,
• Estelle Léonard,
• Christophe Len,
• David Landy,
• Frédéric Hapiot and
• Eric Monflier

Beilstein J. Org. Chem. 2012, 8, 1479–1484, doi:10.3762/bjoc.8.167

• substrates constitutes a real challenge not completely solved so far. Recently, we showed that an association of cyclodextrins (CDs) and amphiphilic phosphanes could significantly improve the catalytic performances in an aqueous rhodium-catalyzed hydroformylation of higher olefins [6]. Herein we clearly

Parallel and four-step synthesis of natural-product-inspired scaffolds through modular assembly and divergent cyclization

• Hiroki Oguri,
• Haruki Mizoguchi,
• Hideaki Oikawa,
• Aki Ishiyama,
• Masato Iwatsuki,
• Kazuhiko Otoguro and
• Satoshi Ōmura

Beilstein J. Org. Chem. 2012, 8, 930–940, doi:10.3762/bjoc.8.105

• diazotransfer, leading to cyclization precursors. The rhodium-catalyzed tandem cyclization and divergent cycloaddition gave rise to tetracyclic and hexacyclic scaffolds by the appropriate choice of dipolarophiles installed at modules 3 and 4. A different piperidine-based manifold 15 bearing an amino group was

• undertaken. Keywords: chemical diversity; divergent cyclization; indole alkaloids; modular assembly; rhodium-catalyzed cyclization–cycloaddition; skeletal and stereochemical diversity; Introduction Biologically intriguing natural products often possess cyclic scaffolds bearing dense arrays of functional

• 3. Rhodium(II)-catalyzed tandem cyclization–cycloaddition [19][20][21] of the tetraketide-like precursors produced distinct multicyclic scaffolds, 4 and 5, differing in the relative orientations of the substructures. This approach illustrates a systematic way of diversifying skeletal arrays in a

Intramolecular carbenoid ylide forming reactions of 2-diazo-3-keto-4-phthalimidocarboxylic esters derived from methionine and cysteine

• Marc Enßle,
• Stefan Buck,
• Roland Werz and
• Gerhard Maas

Beilstein J. Org. Chem. 2012, 8, 433–440, doi:10.3762/bjoc.8.49

• three steps. Upon rhodium-catalysed dediazoniation, two intramolecular carbenoid reactions competed, namely the formation of a cyclic sulfonium ylide and that of a six-ring carbonyl ylide. The S-methyl and S-benzyl ylides 12a and b could be isolated, while S-allyl ylide 12c underwent a [2,3]-sigmatropic

• undergo inter- and intramolecular formation of N-, O-, S- and other ylides [1][2]. The benefit of these transformations, which are usually performed with rhodium- or copper-based catalysts, is given by subsequent rearrangement or addition reactions of the reactive ylides; several recent reviews [3][4][5

• racemisation. A sample of 8a, which was prepared from a slightly racemised sample of 6a (HPLC: 90:10 enantiomeric ratio of the derived methyl ester, which was prepared from 6a and dry methanol in the presence of excess chlorotrimethylsilane) on the latter route, had an enantiomeric ratio of 83:17. Rhodium

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• . The oxacalix[3]arene also formed a complex with rhodium. Elemental analysis supported a composition incorporating the H–Rh–C=O fragment. 1H NMR indicated that this was threaded through the macrocyclic annulus, based on the presence of a peak at −9.70 ppm, and infrared analysis showed a carbonyl