Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• . Recently, also regio- and diastereoselective carbometalation of easily accessible trifluoromethyl-substituted cyclopropenes to access trifluoromethylcyclopropanes has been reported (Scheme 1A) [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. In contrast

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• explanation towards the sole production of the experimentally observed anti-acylated product 15. Although Weller and co-workers have elegantly demonstrated hydride migration, rather than the alternative carbometalation, occurs during rhodium-catalyzed intermolecular alkyne hydroacylation [78], no such

• states for the acyl migration, which exhibit a distorted Ir–C–C’–C’’ four-membered ring geometry, can be located. Directly comparing the hydrometalation process (Figure 1) to the carbometalation process, we see that acyl migration is unfavored, exhibiting activation energies of 19.2 (1bTS2d) to 20.7

• (1aTS2c) kcal/mol. The carbometalated intermediates IN2c and IN2d are 10.3 and 11.7 kcal/mol less stable than their preceding intermediates (IN1a and IN1b), indicating the carbometalation step is an endergonic process. Subsequent reductive elimination of the hydride ligand, via 2cTS3a and 2dTS3b, requires

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

• and useful entry to the synthesis of these heterosubstituted three-membered rings. Results and Discussion To reach these goals, we are describing herein the diastereo- and enantioselective carbometalation reaction of cyclopropenes to provide cyclopropylmetal species. By subsequent stereoselective

• facial selection by the catalyst is required: (i) regioselectivity when R1 is different to H and enantioselectivity when R1 is equal to H (left or right) and (ii) diastereotopic face selection (top or bottom) as described in Scheme 2. Since the pioneering addition of a carbon–metal bond (carbometalation

• achieve good diastereoselectivity during the carbometalation reaction, few conditions needed to be fulfilled in the design of the starting cyclopropenyl ring (Figure 1): The presence of a coordinating group (such as an oxygen) at the C3 position is crucial for the selective facial addition of the incoming

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

• involving catalytic C–C bond construction with the double bond of terminal alkenes (e.g., Heck reaction, hydrometalation followed by functionalization, carbometalation, and olefin metathesis) [10][11][12][13]. However, direct C–C bond formation of the allylic C(sp3)–H bond adjacent to double bonds has

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

• organolithium, organomagnesium, organozinc, and organochromium A, to facilitate addition reactions of appropriate carbon electrophiles such as aldehydes (Scheme 1, top) [1]. In contrast, π-electrophilic carbon-connected late transition metals B facilitate the carbometalation of carbon–carbon multiple bonds

• was utterly consumed, whereas most of iodide 1a and aldehyde 3d were recovered unreacted (Scheme 10, reaction 2). These results indicate that the arylcobalt, rather than the arylchromium intermediate, promoted the allene carbometalation. Additionally, it is thought that the vinylcobalt generated was

Zirconoarylation of alkynes through p-chloranil-promoted reductive elimination of arylzirconates

• Xiaoyu Yan,
• Chao Chen and
• Chanjuan Xi

Beilstein J. Org. Chem. 2014, 10, 528–534, doi:10.3762/bjoc.10.48

• ]. Hydrocarbonation [6][7] and hydrometalation/functionalization [8][9][10][11] of internal alkynes can afford trisubstituted olefins (Scheme 1, routes b and c), respectively. The most exciting progress was the carbometalation of internal alkynes [12][13][14][15][16][17][18][19][20][21][22][23], which involves

• simultaneous addition of a metal atom and an organic residue to alkynes. The newly formed carbon–metal bond can be used for further synthetic transformation toward multi-substituted olefins [24][25][26][27][28][29][30][31][32][33][34][35][36] (Scheme 1, route d). A large number of carbometalation reactions of

Intramolecular carbonickelation of alkenes

• Rudy Lhermet,
• Muriel Durandetti and
• Jacques Maddaluno

Beilstein J. Org. Chem. 2013, 9, 710–716, doi:10.3762/bjoc.9.81

• skeleton was achieved by using NiBr2bipy catalysis. Keywords: alkenes; carbometallation; carbonickelation; cyclization; Heck-type reaction; nickel catalysis; Introduction Carbometalation is a reaction involving the addition of an organometallic species to a nonactivated alkene or alkyne to form a new

• intramolecular carbometalation reaction could help to tackle the problem of the central ring (E) closure. To validate this hypothesis, we retained substrate 13 as a simplified working model. If ether 13 is little functionalized, it bears the methylvinyl moiety that is essential to the construction of 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

• reactions are efficient and direct routes to prepare complex and stereodefined organomagnesium and organozinc reagents. However, carbon–carbon unsaturated bonds are generally unreactive toward organomagnesium and organozinc reagents. Thus, transition metals were employed to accomplish the carbometalation

• group; (2) alkynes bearing a directing group; (3) strained cyclopropenes; (4) unactivated alkynes or alkenes; and (5) substrates that have two carbon–carbon unsaturated bonds (allenes, dienes, enynes, or diynes). Keywords: alkene; alkyne; carbomagnesiation; carbometalation; carbozincation; transition

• have focused on carbometalation reactions that directly transform simple alkynes and alkenes to structurally complex organometallics with high stereoselectivity. In general, carbon–carbon multiple bonds are unreactive with organomagnesium and organozinc reagents. Hence, limited substrates and reagents

Highly stereocontrolled synthesis of trans-enediynes via carbocupration of fluoroalkylated diynes

• Tsutomu Konno,
• Misato Kishi and
• Takashi Ishihara

Beilstein J. Org. Chem. 2012, 8, 2207–2213, doi:10.3762/bjoc.8.249

• , CuI adds oxidatively to the alkyne to form the intermediate Int-C, not Int-D. Since a CF3 group has a very strong electron-withdrawing ability, the CF3Cα—CuIII bond may be stronger than CuIII—Cβ. (In the hydrometalation and the carbometalation reaction of fluoroalkylated alkynes, the same

Stereoselective synthesis of tetrasubstituted alkenes via a sequential carbocupration and a new sulfur–lithium exchange

• Andreas Unsinn,
• Cora Dunst and
• Paul Knochel

Beilstein J. Org. Chem. 2012, 8, 2202–2206, doi:10.3762/bjoc.8.248

• complete retention of the double-bond geometry. Keywords: alkenes; carbometalation; copper; regioselectivity; stereoselectivity; Introduction The stereoselective synthesis of tetrasubstituted alkenes is an important synthetic goal, which may be achieved by carbometalation methods [1][2][3][4][5][6][7][8

• ][9]. The Normant carbocupration of terminal acetylenes allows the stereoselective preparation of trisubstituted alkenes with excellent E/Z ratio [10][11][12]. However, in order to obtain tetrasubstituted alkenes, a carbometalation of an internal alkene is required. This reaction is usually difficult

• due to steric hindrance and proceeds only if electron-withdrawing groups are attached to the alkyne unit to facilitate the carbometalation step. Recently, we studied the chemistry of alkenyl sulfides and their use for carbometalation extensively [13]. Therefore, we envisioned using an alkynyl

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

• Cécile Verrier,
• Pierrik Lassalas,
• Laure Théveau,
• Guy Quéguiner,
• François Trécourt,
• Francis Marsais and
• Christophe Hoarau

Beilstein J. Org. Chem. 2011, 7, 1584–1601, doi:10.3762/bjoc.7.187

• , halogen- or base-assisted metalation–deprotonation, and carbometalation [19][20][21][22] combined with diverse functionalizing agents, such as alkenes and alkynes [23], oxidants [24], nucleophiles, organometallics and arenes [25][26] (Scheme 1). In this review we focus on recent developments in catalytic

Recent advances in carbocupration of α-heterosubstituted alkynes

• Ahmad Basheer and
• Ilan Marek

Beilstein J. Org. Chem. 2010, 6, No. 77, doi:10.3762/bjoc.6.77

• species to an alkyne (carbometalation reaction) is an extremely useful reaction for the preparation of polysubstituted stereodefined alkenyl metal derivatives. When the organometallic species involved is an organocopper reagent, the reaction is termed carbocupration. To be synthetically useful, the new

• is opposite to that predicted on the basis of electronic or steric effects alone [6][7]. Therefore acetylenic ether 10 possessing an additional chelating group was prepared and the regiochemistry of the carbometalation investigated as shown in Scheme 6 [8]. The addition of various organocopper

• undergoes β-elimination at −20 °C (Scheme 3) whilst β-elimination of 15 proceeds only at +20 °C. However, the resulting enamine 16 was found to be unstable and easily underwent isomerization. The formation of a single branched regioisomer 15 in the carbometalation reaction of 14 can be rationalized through

Polar tagging in the synthesis of monodisperse oligo(p-phenyleneethynylene)s and an update on the synthesis of oligoPPEs

• Dhananjaya Sahoo,
• Susanne Thiele,
• Miriam Schulte,
• Navid Ramezanian and
• Adelheid Godt

Beilstein J. Org. Chem. 2010, 6, No. 57, doi:10.3762/bjoc.6.57

• better than (highly) activated MnO2. The use of HOM as an alkyne protecting group is accompanied by carbometalation as a side reaction in the alkynyl–aryl coupling. The extent of carbometalation can be distinctly reduced through substitution of HOM for 1-hydroxyethyl. The strategy of polar tagging is

• -diiodobenzene a better procedure is presented together with the finding that 1,4-dialkyl-2,3-diiodobenzene, a constitutional isomer of 1,4-dialkyl-2,5-diiodobenzene, is one of the byproducts. Keywords: alkyne protecting group; carbometalation; C–C coupling; phenyleneethynylene; polar tagging; Introduction

• : (1) The type of MnO2 used for the removal of the HOM group, (2) carbometalation, a side reaction when using hydroxymethyl as an alkyne protecting group, (3) purity of 1,4-dihexyl-2,5-diiodobenzene, and (4) polar tags in the side chains of building blocks to reduce the number of steps in oligomer