The LANCA three-component reaction to highly substituted β-ketoenamides – versatile intermediates for the synthesis of functionalized pyridine, pyrimidine, oxazole and quinoxaline derivatives

• Tilman Lechel,
• Roopender Kumar,
• Mrinal K. Bera,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2019, 15, 655–678, doi:10.3762/bjoc.15.61

• to β-ketoenamides that are uniquely functionalized alkenes and suitable for a variety of subsequent reactions, in particular in heterocyclic synthesis. This LANCA three-component reaction (LA = lithiated alkoxyallene, N = nitrile, CA = carboxylic acid) was observed for the first time by Oliver Flögel

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

• Irwan Iskandar Roslan,
• Kian-Hong Ng,
• Gaik-Khuan Chuah and
• Stephan Jaenicke

Beilstein J. Org. Chem. 2017, 13, 2739–2750, doi:10.3762/bjoc.13.270

• heterocyclic synthesis, having both electrophilic keto and ester moieties as well as a nucleophilic α-carbon. They can act as dinucleophiles [1][2][3][4], dielectrophiles [5][6][7] or ambiphiles [8][9] in the presence of their complementary coupling partners. Furthermore, they can be prefunctionalized [10][11

Syntheses of 3,4- and 1,4-dihydroquinazolines from 2-aminobenzylamine

• Jimena E. Díaz,
• Silvia Ranieri,
• Nadia Gruber and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2017, 13, 1470–1477, doi:10.3762/bjoc.13.145

• transformations like conversion of amides into nitriles [52][53] or the Beckmann rearrangement [52][54]. They have also been widely employed in heterocyclic synthesis, including microwave-assisted reactions. The recognized wide functional group tolerance, stability and low environmental impact are additional

Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

• Jimena E. Díaz,
• María C. Mollo and
• Liliana R. Orelli

Beilstein J. Org. Chem. 2016, 12, 2026–2031, doi:10.3762/bjoc.12.190

• in heterocyclic synthesis, specially in cyclocondensation reactions [39][40]. In particular, it has enabled the synthesis of the more challenging medium size (7–9 membered) heterocycles by overcoming limitations such as low reactivity and yields, harsh reaction conditions and side reactions typical

• synthesis of 1-aryl-2-iminoazacycloalkanes, by ring closure of ω-arylaminonitriles promoted by PPA esters. This reaction constitutes a novel application of such reagents in heterocyclic synthesis. The procedure involves easily available starting materials and requires remarkably short reaction times. It

• trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of 1-aryl-2-iminopiperidines and hitherto unreported 1-aryl-2-iminoazepanes. The cyclization reaction involves good to high yields and short reaction times, and represents a novel application of PPA esters in heterocyclic

A robust synthesis of 7,8-didemethyl-8-hydroxy-5-deazariboflavin

• Matthias Bender,
• Henrik Mouritsen and
• Jens Christoffers

Beilstein J. Org. Chem. 2016, 12, 912–917, doi:10.3762/bjoc.12.89

• use of iodine (95% yield of product 9), as recommended by Ohlsson et al. [28][29]. Heterocyclic synthesis From the aldehyde 9 the corresponding oxime was formed under buffered conditions [30] and the crude material was directly submitted to reduction with LiAlH4 [31] to furnish amine 10 as a

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• chemistry has been established with the production of the new heterocyclic system 31 from the spiro compound 12. Further application of this tandem methodology offers significant potential in heterocyclic synthesis. Promising in vitro antiplasmodial activity was indicated with a number of the spiro

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• 2H-1,3-oxazines. Therefore, the reaction of diazo esters with 5-alkoxyisoxazoles is a good approach to yield 1,4-di(alkoxycarbonyl)-2-azabuta-1,3-dienes, which are useful building blocks in heterocyclic synthesis [25][26]. We found reaction conditions which allow for the preparation of aryl- and

Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

• Zong Guan,
• Jan C. Namyslo,
• Martin H. H. Drafz,
• Martin Nieger and
• Andreas Schmidt

Beilstein J. Org. Chem. 2014, 10, 832–840, doi:10.3762/bjoc.10.79

• NHCs of indazole which have been generated and applied in heterocyclic synthesis (vide infra) as well as in complex chemistry [13]. Undoubtedly the N-heterocyclic carbenes of imidazole, imidazoline and the triazoles play the most important roles as ligands in metal-organic chemistry [14] or as

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• reactivity, silver(I) salts and complexes have been used to activate either the nucleophile or the imine. Isocyanides have been found to be versatile reagents in heterocyclic synthesis [82][83]. In particular, the α-metallation of isocyanides was accomplished by Schöllkopf [84] and Van Leusen [85] for the

Directed aromatic functionalization

• Victor Snieckus

Beilstein J. Org. Chem. 2011, 7, 1215–1218, doi:10.3762/bjoc.7.141

• , representative of the subject areas described above, demonstrates the current activity in aromatic chemistry. For example, the DoM reaction as applied to the construction of molecules of value for asymmetric synthesis is nicely presented by Rob Britton; lithiation chemistry in service of heterocyclic synthesis

Isotopic labelling studies for a gold-catalysed skeletal rearrangement of alkynyl aziridines

• Paul W. Davies,
• Nicolas Martin and
• Neil Spencer

Beilstein J. Org. Chem. 2011, 7, 839–846, doi:10.3762/bjoc.7.96

• 1,2-alkyl migrations are well-established in gold-catalysed heterocyclic synthesis [12][13], 1,2-aryl shifts are much less common [14][15][16][17]. In relation to these processes, we recently reported the gold-catalysed reactions of aryl substituted alkynyl aziridines, such as 1. Careful choice of

9,10-Dioxa-1,2-diaza-anthracene derivatives from tetrafluoropyridazine

• Graham Pattison,
• Graham Sandford,
• Dmitrii S. Yufit,
• Judith A. K. Howard,
• John A. Christopher and
• David D. Miller

Beilstein J. Org. Chem. 2010, 6, No. 45, doi:10.3762/bjoc.6.45

• systems. Keywords: benzodioxinopyridazine; 9,10-dioxa-1,2-diaza-anthracene; heterocyclic synthesis; nucleophilic aromatic substitution; perfluoroheteroaromatic; tetrafluoropyrazine; Introduction Drug discovery programmes are continually searching for viable synthetic routes to highly novel classes of

2-Arylhydrazononitriles as building blocks in heterocyclic synthesis: A novel route to 2-substituted- 1,2,3-triazoles and 1,2,3-triazolo[4,5-b]pyridines

• Saleh M. Al-Mousawi and
• Moustafa Sh. Moustafa

Beilstein J. Org. Chem. 2007, 3, No. 12, doi:10.1186/1860-5397-3-12

Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes

• Stephen P. Marsden and
• Pascal C. Ducept

Beilstein J. Org. Chem. 2005, 1, No. 5, doi:10.1186/1860-5397-1-5

• chemistry undertaken by allenylsilanes, we expect that these new highly functionalised members of the class will find broad synthetic utility. Our own studies on their application in heterocyclic synthesis will be disclosed in due course. Description of Supporting Information Supporting Information features