Derivatives of the triaminoguanidinium ion, 5. Acylation of triaminoguanidines leading to symmetrical tris(acylamino)guanidines and mesoionic 1,2,4-triazolium-3-aminides

• Jan Szabo,
• Julian Greiner and
• Gerhard Maas

Beilstein J. Org. Chem. 2017, 13, 579–588, doi:10.3762/bjoc.13.57

• -thiadiazolium-2-phenylaminides. We present now the results of our studies on the acylation of triaminoguanidines with carboxylic acid chlorides. Further, we show that N,N’,N’’-tris(benzylamino)guanidine reacts with acid chlorides to afford either the threefold N-acylation product or a mesoionic 1,2,4-triazolium

• hydrochloride (TAG-Cl) in aqueous alkaline solution, can be triply acylated to give 1,2,3-tris(acylamino)guanidinium salts only with acyl chlorides that are not easily hydrolyzed. On the other hand, 1,2,3-tris(benzylamino)guanidinium chloride underwent a threefold N-acylation under carefully controlled

• for II and III, suggesting a positively charged heteroaromatic ring system, are discontinued nowadays, because they do not represent the bond structure appropriately (vide infra). Threefold N-acylation of triaminoguanidinium chloride (1) with acyl chloride 2b. Reaction of 1,2,3-tris(benzylamino

Synthesis of highly functionalized 2,2'-bipyridines by cyclocondensation of β-ketoenamides – scope and limitations

• Paul Hommes and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1170–1177, doi:10.3762/bjoc.12.112

• corresponding β-ketoenamines 2a–e were converted into different β-ketoenamides 3a–g by N-acylation with 2-pyridinecarboxylic acid derivatives. These β-ketoenamides were treated with a mixture of TMSOTf and Hünig’s base to promote the cyclocondensation to 4-hydroxypyridine derivatives. Their immediate O

• we reported on a new pyridine synthesis starting from symmetrically substituted 1,3-diketones 1a and 1b, respectively, that were converted into the corresponding β-ketoenamines and subsequently by N-acylation into β-ketoenamides such as 3a or 3b [1]. Their cyclocondensation followed by O-alkylation

• to this compound class the design of new derivatives is possible thus supplementing the existing collection of available 2,2´-bipyridines. Results and Discussion First we prepared the corresponding β-ketoenamines 2 required for the N-acylation step (Scheme 2). The known compounds 2a and 2b are

Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives

• Larisa Yu. Gurskaya,
• Diana S. Belyanskaya,
• Dmitry S. Ryabukhin,
• Denis I. Nilov,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93

• , B under the superelectrophilic activation. N-Formylation and N-acylation of dihydroquinolinones 2. Superelectrophilic activation of the N-formyl group of compounds 5 and their reaction with benzene. Reactions of amides 1a–u with benzene (and other arenes) under superelectrophilic activation, leading

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• -iodoaniline, PPTS (pyridinium p-toluenesulfonate) and NaBH4 (64%) was followed by N-acylation of the aniline nitrogen atom (80%) provided the target precursor 10. The reaction of 7 with 1 equiv of tributyltin hydride was incomplete, but the use of 2.5 equiv of tributyltin hydride at fixed concentration ([7

Chemoselective O-acylation of hydroxyamino acids and amino alcohols under acidic reaction conditions: History, scope and applications

• Tor E. Kristensen

Beilstein J. Org. Chem. 2015, 11, 446–468, doi:10.3762/bjoc.11.51

• -acetylhydroxyamino acids. They were in fact the first researchers to at all investigate compounds belonging to this class of amino acid derivatives. Under the mantra «acidity favors O-acylation, while alkalinity favors N-acylation», they accomplished this feat by treatment of hydroxy-L-proline, DL-serine, DL

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• irradiation conditions with the substrates adsorbed onto Montmorillonite K-10 clay (Scheme 45) [122]. The formation of compounds 110 proceeded via: (a) N-acylation of aminosugar by the anthranilic acid derivative, and (b) N-acylation of the resulting amide at the aromatic amino group by benzoic acid (or 4

Chromatographically separable rotamers of an unhindered amide

• Mario Geffe,
• Lars Andernach,
• Oliver Trapp and
• Till Opatz

Beilstein J. Org. Chem. 2014, 10, 701–706, doi:10.3762/bjoc.10.63

• for the syntheses of various isoquinoline alkaloids [5][6][7]. Spontaneous dehydrocyanation afforded the 1-benzylated 3,4-dihydroisoquinoline which was subsequently reduced in situ to tetrahydroisoquinoline 3 in a one-pot procedure with sodium borohydride in 63% yield. N-Acylation was effected

Non-cross-linked polystyrene-supported 2-imidazolidinone chiral auxiliary: synthesis and application in asymmetric alkylation reactions

• Quynh Pham Bao Nguyen and
• Taek Hyeon Kim

Beilstein J. Org. Chem. 2013, 9, 2113–2119, doi:10.3762/bjoc.9.248

• result, polymer 3 with 50% active sites was balanced between the largest number of reactive sites and the most suitable solubility property of the polymer itself. N-Acylation of polymer 3 proceeded smoothly to yield polymers 5 in quantitative yields, as evidenced from the 1H NMR spectra of polymers 5

Carbolithiation of N-alkenyl ureas and N-alkenyl carbamates

• Julien Lefranc,
• Alberto Minassi and
• Jonathan Clayden

Beilstein J. Org. Chem. 2013, 9, 628–632, doi:10.3762/bjoc.9.70

• -alkenyl carbamates. Results and Discussion Simple N-alkenyl ureas 1 were prepared by a reported method [2] entailing N-acylation of an acetophenimine with an isocyanate, followed by N-alkylation of the resulting urea. When urea 1a was treated with t-BuLi or s-BuLi in THF at −78 °C for one hour, followed

• method of synthesis: N-acylation of a propiophenimine typically generates an E-alkenylurea, but deprotonation and reprotonation of the urea inverts its geometry to Z [2], probably via an intramolecularly chelated urea-substituted allyl anion [17]. Urea E-3a was treated with n-BuLi in Et2O (the less

Synthesis and characterization of Sant-75 derivatives as Hedgehog-pathway inhibitors

• Chao Che,
• Song Li,
• Bo Yang,
• Shengchang Xin,
• Zhixiong Yu,
• Taofeng Shao,
• Chuanye Tao,
• Shuo Lin and
• Zhen Yang

Beilstein J. Org. Chem. 2012, 8, 841–849, doi:10.3762/bjoc.8.94

• [39][40]. It is noteworthy that some polar groups, including amino, hydroxy and sulfonamide, could not tolerate the conditions of Higa cyclization, and had to be introduced through transformation reactions after the N-acylation step. As depicted in Scheme 3, NH2-derivative 7m was prepared from the NO2

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• achieved at an early stage by N-acylation of the tropinone fragment 287 with 2-methylpropanoyl chloride (288). The resulting amide 289 is then converted to the corresponding imidoyl chloride 290 using phosphorous pentachloride in dichloromethane (which proved to be superior to phosphoryl chloride) followed

Kinetic studies and predictions on the hydrolysis and aminolysis of esters of 2-S-phosphorylacetates

• Milena Trmčić and
• David R. W. Hodgson

Beilstein J. Org. Chem. 2010, 6, 732–741, doi:10.3762/bjoc.6.87

• ; heterobifunctional cross-linker; hydrolysis; kinetics; thiophosphate; Introduction Heterobifunctional cross-linking agents are used widely in protein science for forming covalently-bonded protein-protein complexes [1] and protein-small molecule systems [2]. S-Alkylation and N-acylation processes are used together

• extensively as orthogonal methods to effect hetero-cross-linking. S-Alkylation processes are not affected by competing hydrolysis, however, N-acylation using reactive esters is hampered by competing hydrolysis processes. The aminolysis and hydrolysis of activated esters has been well studied [3], however, the

Bioorthogonal metabolic glycoengineering of human larynx carcinoma (HEp-2) cells targeting sialic acid

• Arne Homann,
• Riaz-ul Qamar,
• Sevnur Serim,
• Petra Dersch and
• Jürgen Seibel

Beilstein J. Org. Chem. 2010, 6, No. 24, doi:10.3762/bjoc.6.24

• ), followed by N-acylation with the activated ester 7 led to the alkyne 8 in a yield of 75% based on D-arabinose. A [3+2] cycloaddition reaction between N-tert-butyl nitrone 9 and 8 and subsequent base-catalyzed ring-opening and hydrolysis afforded N-(1-oxohex-5-ynyl)neuraminic acid (Neu5Hex, 3) in 38% yield

Fused bicyclic piperidines and dihydropyridines by dearomatising cyclisation of the enolates of nicotinyl-substituted esters and ketones

• Heloise Brice,
• Jonathan Clayden and
• Stuart D. Hamilton

Beilstein J. Org. Chem. 2010, 6, No. 22, doi:10.3762/bjoc.6.22

• potassium enolates are more reactive than the lithium enolate and compete too well with N-acylation. We surmised that effective cyclisation onto the acylpyridinium species, avoiding the N- vs. C-acylation problem, might be made possible by decreasing the reactivity of the enolate still further, transforming

2-Phenyl- tetrahydropyrimidine- 4(1H)-ones – cyclic benzaldehyde aminals as precursors for functionalised β²-amino acids

• Markus Nahrwold,
• Arvydas Stončius,
• Anna Penner,
• Beate Neumann,
• Hans-Georg Stammler and
• Norbert Sewald

Beilstein J. Org. Chem. 2009, 5, No. 43, doi:10.3762/bjoc.5.43

• consists of a 4-DMAP catalysed N-acylation reaction with acyl chlorides and usually affords the target compounds in moderate yields [39][40]. We chose Nα-Cbz-protected β-alanine amide (3) as starting material for the synthesis of the 2-phenyltetrahydropyrimidine-4(1H)-one rac-4 to circumvent the difficulty

N-acylation of ethanolamine using lipase: a chemoselective catalyst

• Mazaahir Kidwai,
• Roona Poddar and
• Poonam Mothsra

Beilstein J. Org. Chem. 2009, 5, No. 10, doi:10.3762/bjoc.5.10

• Mazaahir Kidwai Roona Poddar Poonam Mothsra Green Chemistry Research Laboratory, Department of Chemistry, University of Delhi, Delhi-110007, India 10.3762/bjoc.5.10 Abstract The N-acylation of ethanolamine (2) with various fatty acids 1a–d and esters of fatty acids 1e–h using Candida antarctica B

• lipase (Novozym® 435) are described and optimum conditions for selective N-acylation rather than O-acylation are also discussed. Microwave assisted solution phase, solid supported and conventional methods were investigated and results were compared. There is a synergy between the enzyme catalysis and

• acylations, O-acylation and N-acylations, the latter is more favoured in aminoalkanol NH2(CH2)nOH because the amino residue serves as a better nucleophile than the hydroxy group. The selectivity of the aminoalkanol NH2(CH2)nOH towards N-acylation rather than O-acylation is attributed to following reasons (i

Synthesis of (S)-1-(2-chloroacetyl)pyrrolidine- 2-carbonitrile: A key intermediate for dipeptidyl peptidase IV inhibitors

• Santosh K. Singh,
• Narendra Manne and
• Manojit Pal

Beilstein J. Org. Chem. 2008, 4, No. 20, doi:10.3762/bjoc.4.20

• inhibitor Vildagliptin. Keywords: amides; DPP-IV inhibitors; L-proline; N-acylation; 2(S)-cyanopyrrolidine; Background One of the emerging and mechanism based approaches for the treatment of type-II diabetes is dipeptidyl peptidase IV (DPP-IV; CD26; E.C. 3.4.14.5) inhibition with the help of small

• reported process, the major one being the longer reaction time (48 h) at a low temperature (−20 °C). Nevertheless, we observed that N-acylation of L-proline proceeds faster in THF at an elevated temperature. Thus changing the solvent from MeCN [26] to THF and conducting the reaction at reflux we were able