A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

Regioselective cobalt(II)-catalyzed [2 + 3] cycloaddition reaction of fluoroalkylated alkynes with 2-formylphenylboronic acids: easy access to 2-fluoroalkylated indenols

• Tatsuya Kumon,
• Miroku Shimada,
• Jianyan Wu,
• Shigeyuki Yamada and
• Tsutomu Konno

Beilstein J. Org. Chem. 2020, 16, 2193–2200, doi:10.3762/bjoc.16.184

• [2 + 3] cycloaddition reactions with a broader substrate scope for the synthesis of fluoroalkylated indenols is still required. Herein we present a synthesis of 2-fluoroalkylated indenols via [2 + 3] cycloadditions of various fluorinated alkynes with 2-formylphenylboronic acids in the presence of

Unnatural α-amino ethyl esters from diethyl malonate or ethyl β-bromo-α-hydroxyiminocarboxylate

• Eloi P. Coutant,
• Vincent Hervin,
• Glwadys Gagnot,
• Candice Ford,
• Racha Baatallah and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2853–2860, doi:10.3762/bjoc.14.264

• -bromo-α-hydroxyiminocarboxylate and various alkylfuranes. Keywords: α-amino ester; α-hydroxyimino ester; [2 + 4] cycloadditions; [2 + 3] cycloadditions; Knoevenagel; nitrosoacrylate; Suzuki–Miyaura; Introduction Our current work on the chemistry of imidazo[1,2-a]pyrazin-3(7H)-one luciferins [1] has

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• [2 + 3] cycloadditions, one leading to a spiroacetal, which led to the undesired ethyl 5-(benzamidomethyl)isoxazole-3-carboxylate. The addition of ethyl nitroacetate on a 5-methylene-4,5-dihydrooxazole using cerium(IV) ammonium nitrate was also explored and the synthesis of other oxazole-bearing α

• reduction of 13 using zinc and hydrochloric acid gave the target α-amino ester 14 in an 85% yield. To avoid the recourse to more rare and/or expensive heterocyclic aldehydes, we also tried synthetic approaches based on [2 + 3] cycloadditions. As depicted in Scheme 3, the carbon dioxide-producing reaction

• , toluene, dimethylformamide, or acetonitrile) [26][27]. As for a related report [28] describing [2 + 3] cycloadditions between chlorooxime 26 and other methylene-bearing compounds, its reaction with compound 25 gave the spiroacetal 27. However, in the present case this cycloadduct was only detectable by 1H

Conjugates of methylated cyclodextrin derivatives and hydroxyethyl starch (HES): Synthesis, cytotoxicity and inclusion of anaesthetic actives

• Lisa Markenstein,
• Antje Appelt-Menzel,
• Marco Metzger and
• Gerhard Wenz

Beilstein J. Org. Chem. 2014, 10, 3087–3096, doi:10.3762/bjoc.10.325

• known to have a much lower toxic potential compared to CD monomers [20]. Native β-CD was already conjugated by esterification [21], reductive amination [22][23][24][25], amide coupling [26][27] and [2 + 3] cycloadditions [28] to both biogenic and synthetic polymers. Conjugation of CDs to polysaccharides

Parallel solid-phase synthesis of diaryltriazoles

• Matthias Wrobel,
• Jeffrey Aubé and
• Burkhard König

Beilstein J. Org. Chem. 2012, 8, 1027–1036, doi:10.3762/bjoc.8.115

• –t and either copper or ruthenium-catalyzed [2 + 3] cycloadditions. The three reactions and the obtained products 11 (reaction 1), 12 (reaction 2) and 13 (reaction 3) are summarized in Table 2. Reaction 1 follows the established protocol and, gave after removal of the copper salts with a solution of

• , DMSO-d6). Compounds 13, with the exception of compound 13f, were only characterized by mass spectrometry during the synthesis of the compound library. The copper-mediated [2 + 3] cycloadditions are restricted to terminal alkynes. However, the ruthenium-catalysis allows the use of internal alkynes. In

• , 4.25; N, 23.75. Terphenyl scaffold 1 [13][14]; oxazole-pyridazine-piperazine 2 [14][15] and aryl-triazoles 3 and 4 [15][16] as α-helix mimetics. Synthesis of azido-functionalized resins 7 and 9. Copper-catalyzed [2 + 3] cycloadditions of resin-bound azide 7 with five terminal alkynes. Copper-catalyzed