Nitroalkene reduction in deep eutectic solvents promoted by BH₃NH₃

• Chiara Faverio,
• Monica Fiorenza Boselli,
• Patricia Camarero Gonzalez,
• Alessandra Puglisi and
• Maurizio Benaglia

Beilstein J. Org. Chem. 2021, 17, 1041–1047, doi:10.3762/bjoc.17.83

• reaction was cooled to room temperature, and the product was isolated, either by adding 4 mL of water, which dissolves the DES, and extracting the nitroalkane with AcOEt, or by direct separation of the organic residue from the eutectic mixture (see below for recycling experiments and Supporting Information

• accomplished both in glycerol and in DES B, with the eutectic mixture generally performing better than glycerol alone; indeed, α-substituted nitroalkane 4h was isolated in 75% yield after 18 h of reaction at 60 °C. We further explored other DESs, and in particular, we turned our attention to betaine-containing

• with ammonia borane afforded product 6d in 61% isolated yield as 1:1 mixture of diastereomers (the diastereomeric ratio was not influenced by the reaction time, temperature or concentration). Finally, the possibility to develop a reliable, convenient protocol for the isolation of the nitroalkane and

Assessing the possibilities of designing a unified multistep continuous flow synthesis platform

• Mrityunjay K. Sharma,
• Roopashri B. Acharya,
• Chinmay A. Shukla and
• Amol A. Kulkarni

Beilstein J. Org. Chem. 2018, 14, 1917–1936, doi:10.3762/bjoc.14.166

• kept in the feed storage tanks for preheating (see Figure 5). The reagents can be pumped with a suitable pump (viz., peristaltic pump, piston pump, diaphragm pump, etc.) into the mixer M5 and subsequently to reactor R5 which is packed with SiO2-NH2 and CaCl2. The intermediate nitroalkane obtained is

• where it is mixed with the nitroalkane stream. The reaction stream can then be passed through reactor R6 which is packed with polymer-supported (S)-pybox–calcium chloride and maintained at 0 °C. The reaction stream can be further passed to intermediate tank T6 where it can be preheated to 100 °C. The

Conjugate addition–enantioselective protonation reactions

• James P. Phelan and
• Jonathan A. Ellman

Beilstein J. Org. Chem. 2016, 12, 1203–1228, doi:10.3762/bjoc.12.116

• % yield, 95.5:4.5 to 97:3 er). The resulting nitroalkane adduct 159 could be reduced and cyclized to access α,γ-disubstituted γ-lactams. Ellman and co-workers, in the second example of conjugate addition–enantioselective protonation with nitroalkenes, showed that thioacids 160 could be added in high

Recent developments in copper-catalyzed radical alkylations of electron-rich π-systems

• Kirk W. Shimkin and
• Donald A. Watson

Beilstein J. Org. Chem. 2015, 11, 2278–2288, doi:10.3762/bjoc.11.248

• well as discuss current mechanistic understanding of these novel reactions. Keywords: alkene; alkylation; alkyne; catalysis; copper; nitroalkane; radical; Introduction Atom transfer radical (ATR) reactions are extremely useful in organic synthesis and polymer chemistry [1]. These reactions have been

• phenethylamine derivatives, many of which possess known biological activity. For instance, reduction of the fully substituted nitroalkane 19 provides phentermine (20), a clinically prescribed appetite suppressant (Scheme 4) [29][30]. While the precise mechanism of this transformation is not fully understood

• , internal alkenes (such as 39) were not affected during the reaction. Although the reaction proceeds via a distinct mechanism, the authors refer to the transformation as a formal Heck-type alkenylation of alkyl bromides. As with the nitroalkane alkylation chemistry illustrated above, this reaction is a rare

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

• radical 134 concurrently. By carefully selecting reagents/conditions, either reactive intermediate can selectively participate in the designated reaction. As shown in Li and Wang’s work, iminium ion 133 is intercepted by nitroalkane to afford the aza-Henry product 135 while α-amino radical 134 is used to

C–C Bond formation catalyzed by natural gelatin and collagen proteins

• Dennis Kühbeck,
• Basab Bijayi Dhar,
• Eva-Maria Schön,
• Carlos Cativiela,
• Vicente Gotor-Fernández and
• David Díaz Díaz

Beilstein J. Org. Chem. 2013, 9, 1111–1118, doi:10.3762/bjoc.9.123

• ) reaction is a versatile and widely used base-catalyzed C–C bond forming reaction between a nitroalkane and an electrophilic carbonyl derivative (aldehyde or ketone) to produce β-nitroalcohols, which can be transformed into valuable synthetic building blocks [5][6][7][8][9][10]. Some biopolymers such as

• nitromethane (pKa = 10.2) the yield increased considerably (Table 3, entries 2, 6, 10 vs. 1, 5, 9, respectively), albeit without significant diastereoselectivity. Thus, acidity of the nitroalkane plays here a more important role than steric effects [28]. It is worth mentioning that control experiments in the

• organic media under mild conditions, affording the nitroaldol product in variable yields depending on the aldehyde and nitroalkane nature. Moreover, the scale-up of the process between 4-nitrobenzaldehyde and nitromethane could also be achieved on a 1 g scale and in good yield. A comparative kinetics

Continuous flow based catch and release protocol for the synthesis of α-ketoesters

• Alessandro Palmieri,
• Steven V. Ley,
• Anastasios Polyzos,
• Mark Ladlow and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2009, 5, No. 23, doi:10.3762/bjoc.5.23

• . The overall process delivers synthetically useful α-ketoester products in high purity from various nitroalkane inputs and paves the way for more extended reaction sequences. The Uniqsis FlowSyn™ continuous flow reactor comprising of a column holder and heating unit (A) and the reactor coil (B). A