Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• -light-mediated palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines, affording unsaturated γ- and ε-amino acid derivatives with diverse structures. In this methodology, the diazo compound readily transforms into a hybrid α-ester

• reactant ratio produced the desired product 4a in 84% yield as optimal conditions for this protocol (Table 1, entry 13). With the optimized conditions obtained, we examined the generality of our palladium-catalyzed regioselective carboamination of 1,3-dienes with diazo esters and amines (Scheme 2). First

• chemoselectivity (1,2-/1,4-addition = 4:1). Diazo esters suitable for this transformation were examined next. The MCRs with diazo substrates equipped with different substitution patterns were accommodated under the mild photocatalytic conditions to generate the desired 1,4-addition products in moderate to good

Copper-catalyzed multicomponent reaction of β-trifluoromethyl β-diazo esters enabling the synthesis of β-trifluoromethyl N,N-diacyl-β-amino esters

• Youlong Du,
• Haibo Mei,
• Ata Makarem,
• Ramin Javahershenas,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2024, 20, 212–219, doi:10.3762/bjoc.20.21

• IKERBASQUE, Basque Foundation for Science, Alameda Urquijo 36-5, Plaza Bizkaia, 48011 Bilbao, Spain 10.3762/bjoc.20.21 Abstract An efficient multicomponent reaction of newly designed β-trifluoromethyl β-diazo esters, acetonitrile, and carboxylic acids via an interrupted esterification process under copper

• efficient way for the synthesis of β-trifluoromethyl β-diacylamino esters. Furthermore, this reaction represents the first example of a Mumm rearrangement of β-trifluoromethyl β-diazo esters. Keywords: β-carbonyl diazo; copper catalyst; fluoroalkyl diazo; Mumm rearrangement; unsymmetrical β-diacylamino

• esters [28][29][30] have been widely explored, β-trifluoromethyl β-diazo esters have been less investigated, mainly due to the instability of such structures. Therefore, methods for the synthesis of β-trifluoromethyl β-diazo esters and their applications in organic synthesis are needed but remain

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

• Yelong Lei and
• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

• diazo esters 1 and aziridine 2i were performed, generating the corresponding oxazolines 3bi–gi in 73–94% yields. Ethyl 2-diazo-3-oxohept-6-enoate showed the highest activity, affording the desired product 3gi in 94% yield. One diazo amide, 2-diazo-N,N-dimethyl-3-oxobutanamide (1h), was tested with

• heating, diazo esters 1 undergo a Wolff rearrangement to generate ethoxycarbonylketenes A by loss of nitrogen. The nucleophilic attack of 2-arylaziridine 2 on the ketene moiety produces zwitterionic intermediates B, in which the aziridinium is opened to form the benzylic carbocation stabilized through the

• gel column chromatography (PE/EA 2:1, v/v) to give product 3. Oxazoline-containing bioactive natural products. Synthetic methods of oxazoline derivatives. Scopes of aziridines and diazo esters. Proposed reaction mechanism. Direction of tautomerization. Optimization of reaction conditionsa. Supporting

Asymmetric synthesis of CF₂-functionalized aziridines by combined strong Brønsted acid catalysis

• Xing-Fa Tan,
• Fa-Guang Zhang and
• Jun-An Ma

Beilstein J. Org. Chem. 2020, 16, 638–644, doi:10.3762/bjoc.16.60

• ), and PhSO2CF2CHN2 (3, Ps-DFA). Initial screenings were focused on the evaluation of various chiral phosphoric acids that have proven effective in similar aza-Darzens reactions of diazo esters and trifluorodiazoethane [36][37][38][39]. Unfortunately, these endeavors resulted in either no conversion or

Recent advances in transition-metal-catalyzed incorporation of fluorine-containing groups

• Xiaowei Li,
• Xiaolin Shi,
• Xiangqian Li and
• Dayong Shi

Beilstein J. Org. Chem. 2019, 15, 2213–2270, doi:10.3762/bjoc.15.218

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

• 3 were easily prepared through the well-known RhII-catalyzed decomposition of diazo esters in the presence of alkynes to give cyclopropenyl esters 1. Reduction of 1 using DIBAL-H afforded cyclopropenyl alcohols 2 and subsequent protection of the primary alcohols gave 3 in good yields (Scheme 3

On the cause of low thermal stability of ethyl halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155

• transition metal-catalyzed reactions [5]. A large number of diazo esters have been synthesized and an order has been arranged for α-substituents that increase the stability of the diazoesters [3]. Halogen substituents are completely absent from this list of α-substituents. Hence, the relative position of

• compounds (left) and stabilized (R’ = alkyl, R = H, alkyl) diazo esters (right). a) The decay of 2b in toluene-d8 at 35 °C. b) The plot of log(Δ[2b]) vs time. Transition-state energies (kcal/mol) for the release of N2 and formation of the singlet carbenes. The corresponding triplet carbenes are displayed to

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• diazo esters with 5-alkoxyisoxazoles is a good approach to 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes. The reaction conditions for the preparation of aryl- and halogen-substituted 2H-1,3-oxazines and 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes from isoxazoles were investigated. Keywords: diazo esters

• Manning [4][5] discovered the Rh-catalyzed reaction of diazo esters with 3,5-dialkylisoxazoles, benzo[d]isoxazole and 3-chlorobenzo[d]isothiazole leading to the corresponding 2H-1,3-oxazines, 2H-benzo[e][1,3]oxazine and 2H-benzo[e][1,3]thiazine. The authors assumed that the reaction of isoxazoles A with

• diazo esters B involved an isoxazolium N-ylide intermediate C formed by an attack of the rhodium carbenoid onto the isoxazole nitrogen. Furthermore, ylide C could undergo either a 1,2-shift to directly generate oxazine E or a ring opening to 1-oxa-5-azahexa-1,3,5-triene D, followed by a 6π

A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H)-furanones

• Jubi John,
• Eliza Târcoveanu,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 1462–1470, doi:10.3762/bjoc.10.150

• palladium catalysis afforded 4-substituted furanones in good to excellent yields. 4-Hydrazino-3(2H)-furanones could also be synthesized from diazo esters in excellent yields by utilising the developed strategy. We could also efficiently transform the substituted furanones to aza-prostaglandin analogues

• closure of the primary adduct to form the furanone. In this paper, we report our investigations that extend the reaction to heteroatom-containing electrophiles such as imines and diazo esters. Results and Discussion Following the work on nitrostyrenes, Yan et al. also reported a two-step asymmetric route

• entry 2 of Table 2 we can confirm that palladium catalyzes the reaction. The generality of the reaction was checked with different diazo esters 19a–c with 4-chloroacetoacetate esters 2a and 2b under the optimized conditions (diazo ester (1.0 equiv), 4-chloroacetoacetate (1.1 equiv), Pd(PPh3)4 (5 mol

Ethyl diazoacetate synthesis in flow

• Mariëlle M. E. Delville,
• Jan C. M. van Hest and
• Floris P. J. T. Rutjes

Beilstein J. Org. Chem. 2013, 9, 1813–1818, doi:10.3762/bjoc.9.211

• process using microreactor and separation technology. Ethyl diazoacetate (1) can be synthesized in flow via different pathways. Bartrum et al. [18] published a flow synthesis of numerous diazo esters starting from the corresponding arylsulfonylhydrazones, where the diazo moiety was installed through