E-Book, Englisch, Band 26, 632 Seiten, Format (B × H): 152 mm x 229 mm
Gribble Progress in Heterocyclic Chemistry
1. Auflage 2014
ISBN: 978-0-08-100042-7
Verlag: Elsevier Science & Technology
Format: EPUB
Kopierschutz: 6 - ePub Watermark
E-Book, Englisch, Band 26, 632 Seiten, Format (B × H): 152 mm x 229 mm
Reihe: Progress in Heterocyclic Chemistry
ISBN: 978-0-08-100042-7
Verlag: Elsevier Science & Technology
Format: EPUB
Kopierschutz: 6 - ePub Watermark
This is the 26th annual volume of Progress in Heterocyclic Chemistry and covers the literature published during 2013 on most of the important heterocyclic ring systems. This volume opens with two specialized reviews, not restricted to work published in 2013: 'Recent Developments in the Synthesis of Cyclic Guanidine Alkaloids' written by Matthew G. Donahue, and 'Heterocyclic chemistry: a complete toolbox for nanostructured carbon materials' written by Luisa Lascialfari, Stefano Fedeli, and Stefano Cicchi. The remaining chapters examine the 2013 literature on the common heterocycles in order of increasing ring size and the heteroatoms present.
- Recognized as the premiere review of heterocyclic chemistry
- Contributions from leading researchers in the field
- Systematic survey of the important 2013 heterocyclic chemistry literature
Zielgruppe
<p>Organic chemists, academic and industrial chemists, as well as advanced students</p>
Weitere Infos & Material
1 Recent Developments in the Synthesis of Cyclic Guanidine Alkaloids, Matthew G. Donahue
2 Heterocyclic chemistry: a complete toolbox for nanostructured carbon materials, Stefano Cicchi
3 Three-Membered Ring Systems, David J. Lapinsky
4 Four-Membered Ring Systems, Benito Alcaide and Pedro Almendros
5.1 Five-Membered Ring Systems: Thiophenes and Se/Te Derivatives, Edward R. Biehl
5.2 Five-Membered Ring Systems: Pyrroles and Benzo Analogs, Justin M. Lopchuk
5.3 Five-Membered Ring Systems: Furans and Benzofurans, Xiao-Shui Peng, Renhua Fan and Jie Wu
5.4 Five Membered Ring Systems: With More than One N Atom, Larry Yet
5.5 Five-Membered Ring Systems: With N and S (Se) Atoms, Yong-Jin Wu
5.6 Five-Membered Ring Systems: With O & S (Se, Te) Atoms, R. Alan Aitken and Lynn Power
5.7 Five-Membered Ring Systems with O & N Atoms, Franca M. Cordero, Donatella Giomi and Luisa Lascialfari
6.1 Six-Membered Ring Systems: Pyridines and Benzo Derivatives, Tara L. S. Kishbaugh
6.2 Six-Membered Ring Systems: Diazines and Benzo Derivatives, Alison Rinderspacher
6.3 Triazines, Tetrazines and Fused Ring Polyaza Systems, Anton M. Prokhorov and Dmitry N. Kozhevnikov
6.4 Six-Membered Ring Systems: With O and/or S Atoms, Clementina M. M. Santos and Artur M. S. Silva
7 Seven-Membered Rings, John H. Ryan, Jason A. Smith, Christopher Hyland, Adam G. Meyer, Charlotte C. Williams, Alex Bissember and Jeremy Just
8 Eight-Membered and Larger Rings, George R. Newkome
Chapter 1 Recent Developments in the Synthesis of Cyclic Guanidine Alkaloids
Matthew G. Donahue email address: matthew.donahue@usm.edu Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS, USA Abstract
The cyclic guanidine motif, present in complex alkaloids, active pharmaceutical ingredients, and organocatalysts, is discussed beginning with amine guanidinylation and proceeding through numerous cyclization methods. The application of such methods is reviewed in the context of complex alkaloid synthesis. Keywords
Alkaloid; Aminoimidazolidine; Batzelladine; Carboamination; Carbodiimide; Cyanamide; Cycloguanidinylation; Diamination; Electrophile; Guanidine; Guanidinylation; Palau'amine; Saxitoxin; Synthesis; Tetrahydropyrimidine; Thiourea; Urea 1.1. Introduction and Scope of the Review
The cyclic guanidine substructure (typically substituted imidazolin-2-iminium salt or tetrahydropyrimidin-2(1H)-iminium salt) present in complex molecular architectures such as saxitoxin, batzelladines, and palau’amine has enticed synthetic organic chemists to develop new processes to efficiently prepare them. As the field has rapidly evolved, it is now seemingly straightforward for chemists to synthesize such challenging targets. This chapter will provide a broad overview of some of those methods used to construct the cyclic guanidine moiety found in complex alkaloids. A survey of the literature is presented since 2000 and is not meant to be exhaustive in nature, but will serve to introduce the reader to a general background of the various key methods. The first section will provide a brief update on guanidinylation reagents. A recap of cyclization strategies, highlighted in the scheme below, is then presented that demonstrates differential preparations of cyclic guanidines. The second section serves as an illustration of the application of methods used in the total syntheses of three complex molecules. The final section will display some of the unique structures recently isolated from plant material and discovered in medicinal chemistry laboratories.
1.2. Cyclic Guanidines in Organic Chemistry
1.2.1. Amine Guanidinylation Reagents in Organic Chemistry
Cyclic guanidines are typically forged from acyclic precursors, in turn prepared via guanidinylation of amines. The reader is referred to Katritzky and Rogovoy’s 2005 comprehensive review on guanylating agents for a thorough treatment (05ARK49). Following their convention for categorization, reagents of each class are presented: (1) thioureas, (2) isothioureas, (3) aminoiminomethane sulfonic and sulfinic acids, (4) carbodiimides and cyanamides, (5) triflyl guanidines, (6) pyrazole-1-carboximidamides and imidazole-1-yl carboximidamides, and (7) benzotriazole- and benzimidazole-containing reagents. Ansyln’s 2002 review on solid-phase synthesis of guanidinium derivatives is also a beneficial reference (02EJOC3909).
The coupling reagent 2,4,6-trichloro-1,3,5-triazine (TCT, a cyanuric chloride) was found to be an inexpensive way to prepare N,N-di-Boc-protected guanidines using the di-Boc-thiourea (09SL3368). The active guanidinylating agent was determined to be N,N'-di-Boc-carbodiimide upon treatment with N-methylmorpholine. Maki showed that amines (R1 = alkyl, aryl), after conversion to thioureas with N-protected isothiocyanates (R2 = Cbz, Fmoc, CO2Et), can be converted to differentially protected guanidines using the Burgess reagent (14OL1868).
A 2004 report by Izdebski detailed the preparation of ortho-halogenated N-Cbz S-methylisothioureas (04S37). The presence of the halogen atom is claimed to obviate the need for toxic mercuric chloride, which is required for weakly nucleophilic amines. Castillo-Meléndez and Golding developed 3,5-dimethyl-N-nitro-1-pyrazole-1-carboxamidine (DMNPC) for the mild (HgCl2-free) preparation of N-nitroguanidines (04S1655). The nitro group can be cleaved via transfer hydrogenation with formic acid in methanol catalyzed by 10% Pd/C. A polymer-bound pyrazole guanidinylating reagent for the preparation of protecting group free guanidines was developed by Kirschning (06S461). Microwave radiation was found to accelerate the process, and the reagent could be regenerated without deleterious effects. A 2006 report detailed the three-step synthesis of N-hydroxy guanidines from N-Cbz protected thioureas for the synthesis of NG-hydroxy-L-arginine (06OL4035). Looper developed an in situ protocol for the conversion of the shelf-stable potassium salt of N-Cbz-cyanamide into N-Cbz N-TMS-carbodiimide for the preparation of mono-N-acylguanidines (11JOC6967). The reaction has been demonstrated on a wide variety of aliphatic and aromatic amines without the assistance of an exogenous activating agent.
González and coworkers published a one-pot protocol in which an azide is hydrogenated then trapped in situ with N’,N’’-di-Boc-N-triflyl-guanidine (GN-Tf) (10JOC5371). The reaction was deemed competent on a wide variety of carbohydrate substrates. 1.2.2. Methods for Cyclic Guanidine Formation
Two complete reviews on the synthesis of acyclic guanidines have been published and provide excellent up to date coverage of new methods (12CSR2463, 14CSR3406). Wardrop’s extensive review on alkene deamination methods highlights cycloguanidination methods prior to 2012 (12T4067). The chart below depicts some of the recent strategies developed for synthesizing cyclic guanidines.
A few notable achievements highlighting the use of transition metal catalysis to form cyclic guanidines are discussed in the following vignette. Alper has developed a research program predicated on Pd-catalyzed ring-opening reactions of aziridines and pyrrolidines with heterocumulenes (95JA4700, 00JOC5887, 04T73). The maturity of catalytic palladium cyclization methods is evident in the work by Muñiz (08JA763) and Wolfe (13OL5420). The Muñiz cyclization involves guanidination of an olefin by a pendant bis-protected guanidine. The Wolfe olefin carboamination employs an allylic guanidine for sequential cyclization–cross-coupling. The Shi group discovered the Cu(I)-catalyzed intermolecular cycloguanidination of olefins with diaziridines (08OL1087).
A wide variety of novel methods have been published in recent years signifying the intense interest in this area. Madalengoitia discovered that the azanorbornene scaffold, when treated with an in situ-generated carbodiimide, undergoes a 1,3-diaza-Claisen rearrangement to afford fused cyclic guanidines (04OL3409). A most unique synthesis of cyclic guanidines was published utilizing aminyl radical cyclization onto N-acyl cyanamides (10AG(I)2178). The reaction of ß-aminoazides with isocyanates under microwave heating followed by tri-n-butylphosphine effected the formation of 2-aminoimidazolidines in high yield (13JOC5737). The hydrogenation of 2-aminopyrimidines has been shown to be an efficient route to cyclic guanidine-containing amino acids (13TL4526) and substituted 2-anilino 1,4,5,6-tetrahydropyrimidines (14ARK161).
The venerable Mitsunobu reaction has proved its utility in the ring closure of ß-guanidinoalcohols for the synthesis of hydroxyenduracididine derivatives (09EJOC6129). N-Heterocyclic carbenes have been employed in nitrogen atom transfer from electrophilic ruthenium (VI) nitride complexes (11IC2501). Xie delineated the mechanistic details of the titanacarborane monoamide catalyzed reaction of carbodiimides (11OL4562). Xi introduced a method for preparing regioisomers in the presence or absence of trimethylaluminum (12OBC6266). The syntheses of 5-, 6-, and 7-membered N-cycloguanidinyl peptides have been carried out using a solid-phase strategy (14TL1733). 1.2.3. Cyclic Guanidines as Organocatalysts
Cyclic guanidines have emerged as a powerful class of organocatalysts due to their increased nucleophilicity and ability to hydrogen bond (09CAJ488, 12CSR2109, 13S703). A few examples are shown to give the reader a flavor of the type of transformations that have been achieved. The organocatalyst 1,5,7-triazabicyclododecene (TBD) has been found to be an efficient catalyst in the amidation of methyl esters (09JOC9490, 12JPC12389, 12OPRD1967). Terada has shown that the nine-membered ring axially chiral guanidine can induce both high diastereo- and enantioselectivities in the vinylogous aldol reaction of furanones (10AG(I)1858).
1.3. Total Synthesis of Cyclic Guanidine Natural Products
1.3.1. Saxitoxin, Decarbamoylsaxitoxin, Saxitoxinol, and Gonyautoxin 3
Marine sponges are a bountiful source of exceedingly complex toxic alkaloids that serve as the organic chemist’s muse (93CRV1897). The total syntheses of one...
