Direct C(sp³)–H allylation of 2-alkylpyridines with Morita–Baylis–Hillman carbonates via a tandem nucleophilic substitution/aza-Cope rearrangement

• Siyu Wang,
• Lianyou Zheng,
• Shutao Wang,
• Shulin Ning,
• Zhuoqi Zhang and
• Jinbao Xiang

Beilstein J. Org. Chem. 2021, 17, 2505–2510, doi:10.3762/bjoc.17.167

• was necessary to promote the reaction but only with low yield (30%) (Scheme 1c). Recently, electron-deficient 3,5-dimethyl-4-nitroisoxazole and 2-methyl-3-nitroindoles were also served as vinylogous pronucleophiles to proceed the asymmetric allylic alkylation with MBH carbonates [25][26]. Overall, the

Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)

• Tania Xavier,
• Sylvie Condon,
• Christophe Pichon,
• Erwan Le Gall and
• Marc Presset

Beilstein J. Org. Chem. 2021, 17, 2085–2094, doi:10.3762/bjoc.17.135

• known as alkyl hydrogen malonates or hemimalonates, constitute an attractive class of pronucleophiles in the design of eco-compatible syntheses [1]. Indeed, they can serve as efficient precursors of ester enolates through decarboxylation [2][3], generally using a substoichiometric amount of a weak base

• these reagents, which constitute an attractive class of pronucleophiles. Main routes to SMAHOs. Preparation of α-halo-MAHOs. Preparation of SMAHOs from Meldrum's acid. Saponification of substituted malonates. Scope of the mono-esterification of substituted malonic acids. adr = 1:1. Optimization of the

Enantioenriched α-substituted glutamates/pyroglutamates via enantioselective cyclopropenimine-catalyzed Michael addition of amino ester imines

• Zara M. Seibel,
• Jeffrey S. Bandar and
• Tristan H. Lambert

Beilstein J. Org. Chem. 2021, 17, 2077–2084, doi:10.3762/bjoc.17.134

• reactivity might be sufficient to overcome the reactivity limitations of pronucleophiles derived from other α-amino esters [42]. In this paper, we describe the use of cyclopropenimine catalysis for the enantioselective catalytic Michael reaction of α-substituted amino ester imines. Results and Discussion To

Et₃B-mediated and palladium-catalyzed direct allylation of β-dicarbonyl compounds with Morita–Baylis–Hillman alcohols

• Ahlem Abidi,
• Yosra Oueslati and
• Farhat Rezgui

Beilstein J. Org. Chem. 2016, 12, 2402–2409, doi:10.3762/bjoc.12.234

• formation of only water as a side product. This method provides a straightforward and practical route to a range of allylated compounds. Further work is in progress in our laboratory to investigate the Pd catalysis of the reaction of the MBH adducts with various pronucleophiles including nitroalkanes

Bifunctional catalysis

• Darren J. Dixon

Beilstein J. Org. Chem. 2016, 12, 1079–1080, doi:10.3762/bjoc.12.102

• molecules possessing two distinct functional groups to bring about new reactivity and/or selectivity in a reaction of interest. The reactions are typically polar addition reactions of pronucleophiles and electrophiles where, ideally, simple low-cost starting materials are converted into high-value

• reactivity and selectivity in synthetically relevant reactions. Furthermore, owing to the great number of pronucleophiles and electrophiles that are available, the number of polar addition reactions that are amenable to catalysis through the action of bifunctional catalysts is enormous, and consequently, the

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• the main focus has been directed not only to the search for new efficient chiral catalysts, but also to the development of efficient pronucleophiles. This review highlights the utility and first examples of 1H-imidazol-4(5H)-ones and thiazol-4(5H)-ones as pronucleophiles in catalytic asymmetric

• reactions. Keywords: asymmetric catalysis; bifunctional catalysts; 1H-imidazol-4(5H)-ones; pronucleophiles; thiazol-4(5H)-ones; Introduction Asymmetric catalysis [1][2][3] constitutes a very powerful tool for the preparation of enantiomerically pure compounds [4]. Recent efforts in the field have been

• be easily hydrolyzed to provide carboxylic acids or their derivatives carrying different functionalities. The most common pronucleophiles of this type are oxazol-5-(4H)-ones or azlactones (Figure 1a, X = O), which have been thoroughly investigated and reviewed [23][24][25]. On the other hand, since

Chiral phosphines in nucleophilic organocatalysis

• Yumei Xiao,
• Zhanhu Sun,
• Hongchao Guo and
• Ohyun Kwon

Beilstein J. Org. Chem. 2014, 10, 2089–2121, doi:10.3762/bjoc.10.218

• annulations of allenoates and activated alkenes, the first C–C bond forms through nucleophilic addition of the β-phosphonium dienolate intermediate to the activated alkene at its α- or γ-carbon atoms. Conversely, when allenoates are mixed with pronucleophiles that contain acidic protons in the presence of a

Simple two-step synthesis of 2,4-disubstituted pyrroles and 3,5-disubstituted pyrrole-2-carbonitriles from enones

• Murat Kucukdisli,
• Dorota Ferenc,
• Marcel Heinz,
• Christine Wiebe and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 466–470, doi:10.3762/bjoc.10.44

• )nitriles can be used as versatile and readily accessible pronucleophiles, e.g. for the construction of γ-amino acids [32], pyrrolidines [33], as well as pyrroles [34][35]. If an additional conjugated double bond is present, the anions of α-(alkylideneamino)nitriles 3 can undergo an electrocyclic ring

The chemistry of amine radical cations produced by visible light photoredox catalysis

• Jie Hu,
• Jiang Wang,
• Theresa H. Nguyen and
• Nan Zheng

Beilstein J. Org. Chem. 2013, 9, 1977–2001, doi:10.3762/bjoc.9.234

• cations is their conversion to the powerful electrophilic iminium ions, which can be intercepted by a range of pronucleophiles to form a number of important bonds such as C–C, C–N, C–O, and C–P. The chemistry involving iminium ions has seen the most synthetic applications so far. The Whitten group

• . König and coworkers showed that the same aza-Henry reaction can be catalyzed by the organic dye Eosin Y to afford the aza-Henry product 18 (Scheme 5) [67]. In addition to nitroalkanes, dialkyl malonates and malononitrile can be used as pronucleophiles to provide β-diester amine 19 and α-aminonitrile 20

• work much better using the former catalyst. Other types of pronucleophiles such as malonates are also effective in the Mannich reaction. The Rueping group extended the concept of dual catalysis by merging visible light photocatalysis with a metal-catalyzed process (Scheme 10) [77]. To make this