Synthetic Approaches to 3-(2-Nitroalkyl) Indoles and Their Use to Access Tryptamines and Related Bioactive Compounds

Abstract

Introduction 7108 2. Reaction of Indoles with Nitroalkenes 7109 2.1. Uncatalyzed FC Reactions 7109 2.2. Brønsted Acid Catalyzed FC Reactions 7110 2.3. Lewis Acid Catalyzed FC Reactions 7112 2.4. Organocatalyzed FC Reactions 7117 2.5. FC Reactions Included in Tandem, Cascade, and One-Pot Processes 7119 2.6. Base Promoted Conjugate Additions of Indoles to Nitroalkenes 7123 3. Reaction of Indolenine Derivatives 7124 3.1. Reaction of Nitroalkanes with Gramines 7124 3.2. Reaction of Nitroalkanes with Sulfonyl Indoles 7124 3.3. Reaction of Nitroalkanes with Other Derivatives 7126 4. Nitroaldol Reaction on Indolyl-3-carbaldehydes 7126 5. Direct Synthesis of Nitro Indoles by the Fischer Reaction 7129 6. Synthetic Applications of Nitro Indoles 7129 6.1. Synthesis of Tryptophans 7129 6.2. Synthesis of Polycyclic Compounds 7130 6.2.1. Ergot Alkaloids and Related Derivatives 7130 6.2.2. Other Polycyclic Compounds 7132 6.3. Synthesis of β-Carbolines 7135 6.4. Synthesis of Other Tryptamine Derivatives 7141 7. Conclusion 7143 Author Information 7143 Corresponding Author 7143 Notes 7143 Biographies 7143 Acknowledgments 7144 Abbreviations 7144 References 7144

Highly Efficient Tetranuclear ZnII2LnIII2 Catalysts for the Friedel–Crafts Alkylation of Indoles and Nitrostyrenes

“…We screened several reaction parameters, such as the use of different catalysts ( [18][19][20]. We studied the reaction between indole (0.50 mmol) 2 and nitroalkene (0.50 mmol) 3 in EtOH at room temperature and a catalyst loading of 1.0 mol % ( [4][5]. Other catalysts such as 1Eu, 1Gd, 1Nd and 1Tb showed lower yields ( Table 1, entries 1-6).…”

“…The reaction between indole and β-nitrostyrene is important as it gives access to indole-based alkaloids such as melatonin analogues (A), 1,2,3,4-tetrahydro-β-carbolines (THBCs, (B)), and "triptans" (C) (Scheme 1) [3,4].…”

“…The reaction between indole and β-nitrostyrene is important as it gives access to indole-based alkaloids such as melatonin analogues (A), 1,2,3,4-tetrahydro-β-carbolines (THBCs, (B)), and "triptans" (C) (Scheme 1) [3,4]. Nitroalkenes have received considerable attention as active Michael acceptors [5] because the nitro derivatives can be transformed into amino compounds with a variety of different functionalities [6][7][8][9][10].…”

Novel synthesis scheme and in vitro antimicrobial evaluation of a panel of (E)-2-aryl-1-cyano-1-nitroethenes

“…Their strong electrophilic character makes them extremely susceptible to react with diverse nucleophiles. As the nitro group can be easily reduced, they are good precursors for amines, hydroxylamines, esters and salts of nitronic acids and oximes 8,9 . However, the nitroalkenes are often unstable and may display some degree of cytotoxicity, especially these bearing short alkyl chains 9,10 , while interactions of aryl moiety with nitrovinyl system increases their stability.…”

Highly Stereoselective [4+2] and [3+2] Spiroannulations of 2‐(2‐Oxoindolin‐3‐ylidene)acetic Esters Catalyzed by Bifunctional Thioureas

“…[8e,h] Currently, the most used organocatalytic strategies that addressa minosubstituted spirooxindoles involvet he introduction of an itro group [9] as the amino group precursor.H owever,o nly af ew exampleso ft he organocatalyzed enantioselective synthesis of five-or six-membered b-nitro spirocarbocyclic oxindoles have been reported( Scheme1,E q. 1a nd 2).…”