that is required for the van Leusen pyrrole synthesis and is ..
This enzymatic transformation might be called an exampleof a chemomimetic biosynthesis.
The reaction involves a van Leusen's pyrrole synthesis followed ..
Each name reaction is summarized in seven sections such as: Description; Historical perspective; Mechanism; Variations and improvements; Synthetic utility; Experimental; and References authored by a team of world-renowned contributors - some of whom have discovered the very reactions they describe.
Unlike other books on name reactions in organic chemistry, Name Reactions, A Collection of Detailed Reaction Mechanisms and Synthetic Applications focuses on the reaction mechanisms.
Proposed reaction mechanism for Liu’s synthesis of pyrrole-2 ..
Among privileged structures, indoles occupy a central place in medicinal chemistry and alkaloid research. Here we report a flexible and efficient conversion of pyrrole-3-carboxaldehydes to substituted 7-amino-5-cyanoindoles. Phosphine addition to fumaronitrile proceeds with prototropic rearrangement of the initially formed zwitterion to the thermodynamically favored phosphonium ylide, which is poised for in situ Wittig olefination. The predominantly -alkene product positions the allylic nitrile for facile intramolecular Hoeben–Hoesch reaction in the presence of BF3·OEt2. Syntheses of 2,5- and 3,5-disubstituted 7-aminoindoles are illustrated. Additionally, dianion alkylation of the allylic nitrile is demonstrated to furnish, after cyclization, 5,6-disubstituted 7-aminoindoles to further exemplify this scalable and high-yielding method.
Eq 33 describes the synthesis of muscalure, a pheromone of the common house fly. The isocyano group is retained at the bridging carbon when electroreduction is applied (eq 34). A practical synthesis of cyclobutanone is based on the use of TosMIC as an intramolecular connective reagent (eq 35), a method which has been extended to the (first) synthesis of ()- and ()-2-methylcyclobutanone from -1,3-dibromobutane and a chiral analog of TosMIC, (+)-neomenthylsulfonylmethyl isocyanide. Eq 36 gives another recent example of the synthesis of cyclic ketones. Several symmetrical and
Named Reactions List - The Organic Synthesis Database
Each section includes a description of the reaction, the historical perspective, a mechanism for the reaction, variations and improvements on the reaction, synthetic utilities of the reaction, experimental details, and current references to the primary literature.
B., Synthesis of azide-alkyne fragments for click' chemical applications; formation of oligomers from orthogonally protected trialkylsilyl-propargyl azides and propargyl alcohols.
Name Reactions - Organic Chemistry Portal
Click Chemistry -- Publications
Syntheses of Hemoprotein Models that can be Covalently Attached onto Electrode Surfaces by Click Chemistry.
Van Leusen Reaction - Organic chemistry
J., Synthesis and Evaluation of Coumermycin A1 Analogues that Inhibit the Hsp90 Protein Folding Machinery.
Mechanism of the Van Leusen Reaction
S.; Wong, C.-H., 1,2,3-triazole as a peptide surrogate in the rapid synthesis of HIV-1 protease inhibitors.
Click Chemistry Publications - Scripps Research Institute
In conclusion, we have developed a flexible and step-efficient method to obtain highly functionalized 7-aminoindoles from pyrrole-3-carboxaldehydes. This method utilizes a three-component Wittig reaction of pyrrole-3-carboxaldehydes with fumaronitrile and PEt3 to generate predominantly -allylic nitriles, which can be optionally elaborated further by a chemoselective alkylation at C-6. These -allylic nitriles undergo cyclization through an intramolecular Houben–Hoesch reaction to afford highly substituted indoles. A one-pot procedure combining the Wittig and Houben–Hoesch reactions was also demonstrated. While the method is substantially linear, the steps are typically high-yielding with chromatographic purification minimized or eliminated, and intermediates and products isolated by crystallization. The reactions are scalable and require no special precautions or protecting groups—in sum, attributes favorable for large-scale applications. Further studies will aim to expand the scope of this method and to demonstrate its potential for the synthesis of bioactive targets of interest.
Synthesis of 3,4-Disubstituted Pyrroles
Arranged alphabetically by name reactions, the listing provides: Description of the reaction; Historical perspective; A mechanism for the reaction; Variations and improvements on the reaction; Synthetic utilities of the reaction; Experimental details; and References to the current primary literature.
113: 639 [Google Scholar] The mechanism involves ..
Synthetic routes to indoles have long been prized owing to the prevalence of the aromatic heterocycles in natural products as well as synthetic medicinal agents. Classical indole syntheses, including the work of Fischer, Bartoli, Larock, Reissert, and many others, remain benchmarks in the development of heterocyclic methodology. The majority of these approaches utilize a functionalized benzene ring to annulate the 5-membered pyrrolic portion of the indole. In contrast, few synthetic strategies exist that originate from a substituted pyrrole to build up the benzenoid portion of the indole. The latter strategy can benefit from the unique chemistry of pyrroles, which react with electrophiles preferentially at C-2 but exclusively at C-3 when -protected with the sterically cumbersome triisopropylsilyl group. This tunable reactivity allows for ready introduction of the would be C-2 and C-3 substituents of the indole prior to annulation. Further, the intrinsic reactivity of pyrroles at C-2 introduces a disconnection optimal for the indole-forming cyclization itself. Tactical issues of symmetry and regiochemistry inherent to routes from substituted benzene rings are avoided. This strategy, shown in Figure , utilizes a three-component Wittig reaction of pyrrole-3-carboxaldehydes with fumaronitrile and a trialkylphosphine to generate predominantly -alkenes. These allylic nitriles are positioned for intramolecular cyclization under Houben–Hoesch conditions to furnish, after aromatization, substituted 7-aminoindoles. An optional tailoring step to install C-6 substituents prior to ring closure can also be envisioned. This scheme would allow for control of the C-2, C-3, and C-6 indole substituents on the resulting 7-amino-5-cyanoindoles that are not readily accessible using existing methods. The amine (e.g., by diazotization, acylation) and the nitrile (e.g., by hydration, hydrolysis, reduction, etc.) can be differentially modified for rapid structural diversification. Potential targets (Figure ) include a class of potent β-secretase 1 (BACE1) inhibitors, a class of nicotinic acetylcholine receptor (nAChR) allosteric modulators, and analogues of recently reported inhibitors of glycerol-3-phosphate acyltransferase (GPAT).
2.2 Knorr and Paal-Knorr pyrrole ..
Each section includes a description of the reaction, the historical perspective, a mechanism for the reaction, variations and improvements on the reaction, synthetic utilities of the reaction, experimental details, and references to the current primary literature.
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