Cobalt-catalyzed nucleophilic addition of the allylic C(sp³)–H bond of simple alkenes to ketones

• Tsuyoshi Mita,
• Masashi Uchiyama,
• Kenichi Michigami and
• Yoshihiro Sato

Beilstein J. Org. Chem. 2018, 14, 2012–2017, doi:10.3762/bjoc.14.176

• would lead to a low-valent allylcobalt(I) species, and then C–C bond formation of IV with 2a would proceed at the γ-position to produce cobalt alkoxide(I) V [28][29][31][32][33][34][35][36][37][38][39]. Transmetalation between V and AlMe3 would furnish branched aluminium alkoxide VI along with the

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• and migratory addition into the proximal alkyne. Transmetalation of the vinylpalladium with the boronic acid and reductive elimination finally leads to alkylidenefluorenes 49. This multicomponent strategy allows the variation of the alkyne, the boronic acid and the diaryliodonium salts, but the use of

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

• , leading to multi-substituted carbon frameworks (Scheme 1, bottom) [2][3]. The nucleophilic and π-electrophilic organometallic intermediates are used properly in their favorable circumstances. Transmetalation is one of the most vital elemental processes used to drastically change the reactivity of

• organometallics, involving a wide range of transition metal-catalyzed reactions. For example, transmetalation between an organonickel (or organocobalt) complex and chromium salt results in the formation of a highly nucleophilic organochromium species, which enables efficient addition to aldehydes to give

• alkynyl iodoarene cyclization/borylation to form cyclized vinylboronic esters, in which transmetalation between the generated vinylcobalt and chromium salt was a critical step (Scheme 4) [16]. As part of our continuing work on the cobalt-catalyzed functionalization of carbon–carbon unsaturated bonds, a

Cobalt-catalyzed directed C–H alkenylation of pivalophenone N–H imine with alkenyl phosphates

• Wengang Xu and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2018, 14, 709–715, doi:10.3762/bjoc.14.60

• radical to give a diorganocobalt intermediate C. The C–C-bond rotation of the radical anion 2•− or the transiently formed alkenyl radical might be responsible for the stereochemical mutation of the C=C bond observed in some cases. The reductive elimination of C and subsequent transmetalation with the

Progress in copper-catalyzed trifluoromethylation

• Guan-bao Li,
• Chao Zhang,
• Chun Song and
• Yu-dao Ma

Beilstein J. Org. Chem. 2018, 14, 155–181, doi:10.3762/bjoc.14.11

• mechanistic studies (Scheme 35). First, the key intermediate CF3CuILn is generated in situ by the reaction of TMSCF3 with Cu(II) reagent, followed by transmetalation with activated Ar−H generating the (aryl)CuI(CF3) species C, which might be oxidized to the corresponding (aryl)CuIII(CF3) intermediate D

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

• bearing a N-enoyl sultam moiety 84 instead. A 3-key step strategy involving a copper-mediated reduction, a transmetalation and an asymmetric alkylation was adopted for the preparation of monofluoroalkenes 85 (Scheme 16). After some synthetic modifications, Fmoc-Orn(Ns)-ψ[(Z)-CF=CH]-Orn(Ns) [48], Fmoc-Lys

• reduction, transmetalation and asymmetric alkylation by Fujii and co-workers. Synthesis of (E)-monofluoroalkene-based dipeptide isostere by Fujii and co-workers. Diastereoselective synthesis of MeOCO-Val-ψ[(Z)-CF=C]-Pro isostere by Chang and co-workers. Asymmetric synthesis of Fmoc-Ala-ψ[(Z)-CF=C]-Pro by

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 novel approach to oxoisoaporphine alkaloids via regioselective metalation of alkoxy isoquinolines

• Benedikt C. Melzer and
• Franz Bracher

Beilstein J. Org. Chem. 2017, 13, 1564–1571, doi:10.3762/bjoc.13.156

• were inspired by Knochel’s reports on the direct metalation of isoquinoline [22] and 6,7-dimethoxyisoquinoline [23] as well as by our own results for the metalation of various alkoxyisoquinolines [13] at C-1 with the Knochel–Hauser base TMPMgCl·LiCl. Transmetalation of the intermediate organomagnesium

• extended to 6-methoxyisoquinoline (7c). Unfortunately, transmetalation with ZnCl2 at 0 °C followed by palladium-catalyzed (5 mol % Pd(dba)2/ 10 mol % P(2-furyl)3 or 1 mol % Pd2(dba)3/2 mol % RuPhos) Negishi cross-coupling reaction with methyl 2-bromo-5-methoxybenzoate did not lead to the expected methyl 2

Direct catalytic arylation of heteroarenes with meso-bromophenyl-substituted porphyrins

• Alexei N. Kiselev,
• Olga K. Grigorova,
• Alexei D. Averin,
• Sergei A. Syrbu,
• Oskar I. Koifman and
• Irina P. Beletskaya

Beilstein J. Org. Chem. 2017, 13, 1524–1532, doi:10.3762/bjoc.13.152

• ) metalates heteroarene in the presence of K2CO3 forming Het-Cu-OAc species and this process proceeds faster than the oxidation of Pd(0). Then one may suppose the transmetalation reaction at heteroarene according to Scheme 4 which provides the formation of Ar-Pd-Het intermediate giving the target coupling

• benzothiazole, benzoxazole, N-methylbenzimidazole and caffeine. Plausible action of palladium and copper catalysts with transmetalation step. Dirylation of zinc di-meso-(bromophenyl)porphyrinates 10–12 with benzothiazole, benzoxazole and N-methyl benzimidazole. Polyarylation of zinc tetrakis-meso-(bromophenyl

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

• was developed. The route initiated from compound 4a and pivaloyl-protected glycosyl bromide 2b, the β-C-arylglucoside 5 was obtained with high stereoselectivity in one step after a halogen–lithium exchange/transmetalation/coupling sequence. Cryogenic temperatures and catalysts were not required. The

• converted to the arylzinc species by the reaction with n-BuLi in the mixed solvent (toluene/DBE), followed by transmetalation with ZnBr/LiBr complex in DBE, and then the active species reacted with 2,3,4,6-tetra-O-pivaloyl-α-D-glucopyranosyl bromide (2b) [16]. But the reaction gave only 35% of desired 5

• equiv 2b gave a good result, the amount of 5” was greatly reduced (Table 1, entry 4), while the content of 5 in the crude product was increased to 68% and the isolated yield was 77.7%. It was presumable that a iodine–lithium–zinc exchange and the transmetalation proceeded better than a bromide–lithium

Synthesis of tetrasubstituted pyrazoles containing pyridinyl substituents

• Josef Jansa,
• Ramona Schmidt,
• Ashenafi Damtew Mamuye,
• Laura Castoldi,
• Alexander Roller,
• Vittorio Pace and
• Wolfgang Holzer

Beilstein J. Org. Chem. 2017, 13, 895–902, doi:10.3762/bjoc.13.90

• -coupling reaction with organozinc compounds [23][24] is a valuable tool for the formation of C–C bonds, particularly in the presence of functional groups. The employed organozinc reagents are relatively reactive nucleophiles undergoing rapid transmetalation with appropriate transition metal species, for

Rh-Catalyzed reductive Mannich-type reaction and its application towards the synthesis of (±)-ezetimibe

• Motoyuki Isoda,
• Kazuyuki Sato,
• Yurika Kunugi,
• Satsuki Tokonishi,
• Atsushi Tarui,
• Masaaki Omote,
• Hideki Minami and
• Akira Ando

Beilstein J. Org. Chem. 2016, 12, 1608–1615, doi:10.3762/bjoc.12.157

• enolate 7 involved the 1,4-reduction of α,β-unsaturated ester 2 by 6 and the transmetalation with a zinc species to give the Reformatsky-type reagent Int A. This intermediate Int A reacts immediately with the imine to give the corresponding intermediate Int B. Subsequently, intramolecular cyclization of

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands

• Dirk Meyer and
• Thomas Strassner

Beilstein J. Org. Chem. 2016, 12, 1557–1565, doi:10.3762/bjoc.12.150

• = Cl, CF3COO, CH3) has been prepared by transmetalation reactions from the corresponding silver complexes and chloro(methyl)(cyclooctadiene)palladium(II). The dimethyl(1-(2-pyrimidyl)-3-(2,6-diisopropylphenyl)imidazolin-2-ylidene)palladium(II) complex was synthesized via the free carbene route. All

• silver complexes 5–8 by transmetalation with chloro(methyl)(cyclooctadiene)palladium(II) [(COD)PdII(CH3)Cl] either in dichloromethane (A) or acetonitrile (B, Scheme 1). Although two isomers could be formed we only observed the isomer B, where the methyl group is located cis to the carbene carbon atom

On the mechanism of imine elimination from Fischer tungsten carbene complexes

• Philipp Veit,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2016, 12, 1322–1333, doi:10.3762/bjoc.12.125

• pentacarbonyl metal fragments (M = Cr, Mo, W) have further proven to be effective carbene transfer agents to late transition metals in transmetalation reactions [9][10][11][12][13][14][15]. The manifold synthetic access routes to carbene complexes even allows the assembly of multicarbene and multimetal carbene

Copper-catalyzed [3 + 2] cycloaddition of (phenylethynyl)di-p-tolylstibane with organic azides

• Mizuki Yamada,
• Mio Matsumura,
• Yuki Uchida,
• Masatoshi Kawahata,
• Yuki Murata,
• Naoki Kakusawa,
• Kentaro Yamaguchi and
• Shuji Yasuike

Beilstein J. Org. Chem. 2016, 12, 1309–1313, doi:10.3762/bjoc.12.123

• organoantimony compounds in organic synthesis has attracted much interest during the last two decades [25][26]. Trivalent organoantimony compounds (stibanes) such as aryl- and ethynylstibanes are useful transmetalation agents in Pd-catalyzed cross-coupling reactions with aryl halides and acyl chlorides [27][28

Cationic Pd(II)-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

• Takashi Nishikata,
• Alexander R. Abela,
• Shenlin Huang and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2016, 12, 1040–1064, doi:10.3762/bjoc.12.99

• can undergo transmetalation with an arylboronic acid in the absence of base even at 0 °C [219][220]. Wu and co-workers have also reported the interesting reactivities of neutral palladacycles with arylboronic acids (Scheme 15). Under their conditions, BQ and high temperature were critical to obtain

• presumably starts from the generation of a cationic palladacycle, which may undergo a facile transmetalation with an arylboronic acid without prior activation by base (Scheme 24) [241][242][243][244][245][246][247][248]. This step is followed by reductive elimination of a diarylpalladium(II) species

Pyridylidene ligand facilitates gold-catalyzed oxidative C–H arylation of heterocycles

• Kazuhiro Hata,
• Hideto Ito,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2015, 11, 2737–2746, doi:10.3762/bjoc.11.295

• be a key step in the catalytic cycle consisting of transmetalation with arylsilane, C–H activation and reductive elimination [69]. While gold(I) complexes bearing various ligands are used as gold(III) precursors, it remains unclear whether ligands can still coordinate to the gold center or not under

• confirmed that the esterification of 2-iodobenzoic acid takes place to give 5 under the reaction conditions; 2-iodobenzoic acid was smoothly converted to 5 in chloroform/methanol solution at 65 °C. Transmetalation of gold(III) complex B with arylsilane 2 affords monoarylated gold(III) intermediate C. The

• of arylsilane 4 likely occurs via over-transmetalation of monoarylated gold(III) species C with arylsilane 2 or disproportionation of C [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81]. Oxidation process of gold In all reaction progress experiments with the three gold catalysts (Figure 2

Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

• Takamichi Wakamatsu,
• Kazunori Nagao,
• Hirohisa Ohmiya and
• Masaya Sawamura

Beilstein J. Org. Chem. 2015, 11, 2444–2450, doi:10.3762/bjoc.11.265

• the present copper catalysis is proposed in Figure 1. An alkoxycopper complex (A) is initially formed by the reaction of CuOAc, t-BuOK and P(OPh)3. Boron-to-cupper transmetalation between A and the alkylborane 2 occurs to form an alkylcopper(I) species (B) and a t-butoxyborane (9-BBN-Ot-Bu) [12][13

Copper-catalyzed arylation of alkyl halides with arylaluminum reagents

• Bijay Shrestha and
• Ramesh Giri

Beilstein J. Org. Chem. 2015, 11, 2400–2407, doi:10.3762/bjoc.11.261

• , Zn and Sn in cross-coupling, the utility of organometallic complexes of Al are limited [13][14][16][17][18][19][20][21]. In many cases, direct transmetalation of organoalanes to Pd are sluggish and require ZnCl2 or CdCl2 to facilitate reactions through sequential transmetalations [19]. In some cases

• product yields for the current coupling of triarylaluminum reagents with alkyl halides (Table 1). As such, we believe that organoaluminate complexes such as 18, generated from the binding of LiCl to three-coordinate triarylaluminum reagents, are the actual species in solution that undergo transmetalation

• form triorganoaluminate species in the presence of anions in solution [52][53][54][55][56][57]. In addition, organoaluminum reagents have been demonstrated to undergo transmetalation with Cu salts based on their participation in allylic and conjugate addition reactions [11][15][43]. Similar Cu

Pyridinoacridine alkaloids of marine origin: NMR and MS spectral data, synthesis, biosynthesis and biological activity

• Louis P. Sandjo,
• Victor Kuete and
• Maique W. Biavatti

Beilstein J. Org. Chem. 2015, 11, 1667–1699, doi:10.3762/bjoc.11.183

• presence of tributyltin hydride and azobisisobutyronitrile (AIBN) (Scheme 7) [67]. Two methods were reported for the synthesis of subarine (37) where the first (method A) is a versatile path based on the outcome yield. The key step in method A is the Stille cross-coupling characterized by a transmetalation

• successfully performed in six steps with an overall yield of 6.5%. The steps included an organometallic intermediate and a Negishi cross-coupling reaction characterized by a transmetalation with zinc and palladium. The benzonaphthyridinone product was transformed into a bromobenzonaphthyridine intermediate by

Sequential decarboxylative azide–alkyne cycloaddition and dehydrogenative coupling reactions: one-pot synthesis of polycyclic fused triazoles

• Kuppusamy Bharathimohan,
• Thanasekaran Ponpandian,
• A. Jafar Ahamed and
• Nattamai Bhuvanesh

Beilstein J. Org. Chem. 2014, 10, 3031–3037, doi:10.3762/bjoc.10.321

• with azide derivative 1 to yield the copper salt of 3 and a transmetalation reaction gave the intermediate B. We assumed that the pivalate group replaces the acetate group in B and may produce C. The pivalate group in C facilitates the palladium insertion to the C–H bond to give D and subsequent

A novel 4-aminoantipyrine-Pd(II) complex catalyzes Suzuki–Miyaura cross-coupling reactions of aryl halides

• Claudia A. Contreras-Celedón,
• Darío Mendoza-Rayo,
• José A. Rincón-Medina and
• Luis Chacón-García

Beilstein J. Org. Chem. 2014, 10, 2821–2826, doi:10.3762/bjoc.10.299

• their rapid transmetalation with palladium(II) complexes [11]. Although in recent years there have been numerous studies on the SM cross-coupling reaction, the necessity for a simple procedure that allows the formation of C–C bonds in functionalized substrates remains. There have been ongoing efforts to

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

•  37) [80]. It should be emphasized that the latter step of the proposed reaction machinery referred as “redox synergy” is in clear conflict with the commonly reported alternative invoking transmetalation/reductive elimination steps (see Schemes 33 and 34). The catalytic superiority of bimetallic

Synthesis and structure of trans-bis(1,4-dimesityl-3-methyl-1,2,3-triazol-5-ylidene)palladium(II) dichloride and diacetate. Suzuki–Miyaura coupling of polybromoarenes with high catalytic turnover efficiencies

• Jeelani Basha Shaik,
• Venkatachalam Ramkumar,
• Babu Varghese and
• Sethuraman Sankararaman

Beilstein J. Org. Chem. 2013, 9, 698–704, doi:10.3762/bjoc.9.79

• complexes Complexes 1 and 2 were synthesized from the corresponding silver carbene complex by transmetalation as reported earlier for the synthesis of bis(1,4-diphenyl-3-methyl-1,2,3-triazol-5-ylidene)palladium(II) derivatives 3 and 4 (Figure 1 and Scheme 1), respectively [26][27]. Treatment of 1,4

• -dimesityl-3-methyl-1,2,3-triazolium iodide with freshly prepared silver oxide followed by transmetalation with Pd(Cl)2(CH3CN)2 yielded 1 as a pale yellow solid in 87% (Scheme 1). The acetate complex 2 was prepared by the transmetalation of the silver carbene complex with Pd(OAc)2. Addition of Pd(OAc)2 to in

Inter- and intramolecular enantioselective carbolithiation reactions

• Asier Gómez-SanJuan,
• Nuria Sotomayor and
• Esther Lete

Beilstein J. Org. Chem. 2013, 9, 313–322, doi:10.3762/bjoc.9.36

• the success achieved in the procedures described above, stoichiometric use of chiral ligands is usually required. However, recently a general catalytic methodology for the enantioselective intermolecular addition of alkyllithiums has been reported, though it implies transmetalation to copper complexes