Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• variety of reactions; that are, phosphite- or Lawesson’s reagent-mediated olefination reactions (to introduce DTF motifs), Ramirez/Corey–Fuchs dibromo-olefinations followed by Sonogashira couplings (to introduce enediynes motifs), and Knoevenagel condensations (to introduce the vinylic diester motif). By

• -annelated IF-DTF 12 by removal of the tosyl (Ts) group under alkaline conditions, followed by nucleophilic substitution to incorporate the hexyl chain on the pyrrole. Furthermore, treatment of the IF-DTF ketone 4 with Lawesson’s reagent (using a recently established protocol [20]) yielded the large dimer 13

• smaller fluorene PAH. These compounds were prepared by a Lawesson’s reagent-promoted coupling between fluorenone 5 and the Ts-protected 1,3-dithiole-2-thione building blocks 2 and 3, respectively, shown in Scheme 3 (albeit in modest yields). Fluorene-based DTF compounds have previously been explored in

Synthesis of sulfur karrikin bioisosteres as potential neuroprotectives

• Martin Pošta,
• Václav Zima,
• Lenka Poštová Slavětínská,
• Marika Matoušová and
• Petr Beier

Beilstein J. Org. Chem. 2022, 18, 549–554, doi:10.3762/bjoc.18.57

• (14), respectively, following a published procedure [21][23], while karrikin KAR2 (2) was synthesized from ᴅ-xylose [24]. The conversion of karrikins 1–4 to the corresponding C2 thiones 9–12 was accomplished using microwave-assisted heating with Lawesson’s reagent and hexamethyldisiloxane (HMDO

• pyromeconic acid (5) [26] and allomaltol (13) [27]. Unfortunately, the treatment of hydroxypyranones 5, 13 and 14 with Lawesson’s reagent resulted in an inseparable mixture (approx. 1:1) of pyranthiones 6a, 15a, 16a and thiopyranthiones 6b, 15b, 16b in low yields up to 30% in all the cases. In order to

• increase the selectivity and the yields, an improved procedure [28] has been tested. An additive, HMDO applied together with Lawesson’s reagent improved significantly the yields of thiopyranthiones 6b, 15b, 16b over pyranthiones 6a, 15a, 16a. In contrast to previous reports on related systems [28][29][30

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• alkylation of the anion of pyrrolidin-2-one (16) with ethyl bromoacetate to afford the known compound ethyl 2-(2-oxopyrrolidin-1-yl)acetate (17) [31][32][33] in 77% yield. Thionation of 17 with Lawesson’s reagent in toluene at 80 °C gave the thione 18 as a yellow oil (86%). Reaction of 18 with phenacyl

• such enaminones by the route shown in Scheme 4. Alkylation of piperidin-2-one (23) with ethyl bromoacetate followed by treatment of the resulting lactam [66][67] with Lawesson’s reagent in toluene at 80 °C gave the thione 24 in 83% overall yield. Reaction of 24 with phenacyl bromide and its 4-methoxy

• ) Lawesson’s reagent, toluene, 80 °C, 18 h; (iii) BrCH2COPh, MeCN, rt, overnight; (iv) P(OEt)3, NEt3, MeCN, rt, 18 h; (v) AcOH, microwaves (150 W, 140 °C), 10 min; (vi) SiO2, xylene, microwaves (150 W, 150 °C), 3.5 min. Proposed mechanism for the formation of pyrrolizidine 19a from enaminone (E)-15a. Synthesis

A chromatography-free and aqueous waste-free process for thioamide preparation with Lawesson’s reagent

• Ke Wu,
• Yichen Ling,
• An Ding,
• Liqun Jin,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2021, 17, 805–812, doi:10.3762/bjoc.17.69

• Ke Wu Yichen Ling An Ding Liqun Jin Nan Sun Baoxiang Hu Zhenlu Shen Xinquan Hu College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P.R. China 10.3762/bjoc.17.69 Abstract After completing the thio-substitution with Lawesson’s reagent, ethanol was found to be

• effective in the decomposition of the inherent stoichiometric six-membered-ring byproduct from the Lawesson’s reagent to a highly polarized diethyl thiophosphonate. The treatment significantly simplified the following chromatography purification of the desired thioamide in a small scale preparation. As

• generate P-containing aqueous waste, and only organic effluents were discharged. It is believed that the optimized procedure offers the great opportunity of applying the Lawesson’s reagent for various thio-substitution reactions on a large scale. Keywords: chromatography-free; Lawesson’s reagent; scale-up

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• compounds in a Barton–Kellogg coupling manner to yield the corresponding olefins. To this context, the carbonyl species were first transformed into the thiocarbonyl systems in the presence of Lawesson’s reagent which were then reacted with diazosumanene 59 to furnish the corresponding alkene systems. It has

Ferrocenyl-substituted tetrahydrothiophenes via formal [3 + 2]-cycloaddition reactions of ferrocenyl thioketones with donor–acceptor cyclopropanes

• Grzegorz Mlostoń,
• Mateusz Kowalczyk,
• André U. Augustin,
• Peter G. Jones and
• Daniel B. Werz

Beilstein J. Org. Chem. 2020, 16, 1288–1295, doi:10.3762/bjoc.16.109

• capillaries with a Melt Temp II apparatus. Starting materials: D–A cyclopropanes 5a–g were obtained following the reported procedure [28]. Ferrocenyl thioketones 8a–g were obtained by thionation of corresponding ferrocenyl ketones [29] by treatment with Lawesson’s reagent [30]. Ferrocenyl β-naphthyl

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• -Hydrazinylpyridines (a) and pyridinylhydrazones (b), as well as their acylated derivatives (c), are versatile scaffolds for the preparation of triazolopyridines (Scheme 1). The known methods for the [1,2,4]triazolopyridine ring formation use various condensation agents such as HCOOH, orthoesters, Lawesson’s reagent

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• diarylmethyl alcohols with hydride sources. These reactions require a preliminary C–OH bond activation by Brønsted or Lewis acids. Several reagent systems have recently been employed to achieve this goal, including: NaBH4–CF3COOH [26], ZnI2–NaBH3CN [27], HI–Pred [28], H3PO2–I2 [29][30], Mo(CO)6-Lawesson’s

• reagent [31], PBr3 [32], BF3·Et2O–dibutyl ether [33] and silanes (Si–H) in the presence of various Lewis acids: B(C6F5)3 [34][35][36], InCl3 [37][38], H3[PW12O40]×nH2O [39], Ca(NTf2)2 [40], Bi(OTf)3 [41], Sn(IV)-montmorillonite [42] and PdCl2 [43]. It is interesting that Seto et al. reported that Et3SiH

A novel application of 2-silylated 1,3-dithiolanes for the synthesis of aryl/hetaryl-substituted ethenes and dibenzofulvenes

• Grzegorz Mlostoń,
• Paulina Pipiak,
• Róża Hamera-Fałdyga and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 1900–1906, doi:10.3762/bjoc.13.185

• thiodibenzosuberone (1i) were prepared from the corresponding ketones by treatment with Lawesson’s reagent (L.R.) in toluene upon irradiation with microwaves (150 W) over 2 min [32]. The most efficient method for the preparation of thiofluorenone (1c) was the thionation of fluorenone by simultaneous passing of dry

Synthesis of the heterocyclic core of the D-series GE2270

• Christophe Berini,
• Thibaut Martin,
• Pierrik Lassalas,
• Francis Marsais,
• Christine Baudequin and
• Christophe Hoarau

Beilstein J. Org. Chem. 2017, 13, 1407–1412, doi:10.3762/bjoc.13.137

• , THF/H2O (2:1), rt, 14 h, 93%. e) (i) 8, Bis(pinacolato)diboron, Pd(OAc)2 (5 mol %), CyJohnPhos (20 mol %), KOAc, dioxane, 1 h; (ii) K3PO4, dioxane/H2O (4:1), 110 °C, 14 h, 82–99%. f) Lawesson’s reagent, CH2Cl2, 40 °C, 12 h, 91–94%. g) Ethyl bromopyruvate, CaCO3, THF/EtOH (1:1), 60 °C, 24 h. Synthesis

• of chiral thioamide 16. Reaction conditions: a) SnCl2∙2H2O, dioxane/H2O (1:3), 0 °C to rt, 5 h, then NaHCO3, benzyl chloroformate, rt, 18 h, 96%. b) TBDMSCl, imidazole, DMF, rt, 16 h, 99%. c) LiOH∙H2O, DME/H2O (1:1), 0 °C to rt, 72 h, then HCl, 96%. d) DCC, HOSu, THF, rt, 16 h, then Lawesson’s

• reagent, DME, rt, 36 h, 72%. Synthesis of the heterocyclic core of the D-series GE2270. Reaction conditions: a) TBDMSOTf, NEt3, DCM, 0 °C, 1 h, 51%. b) NBS, THF, 1 h, 94%. c) 16, MS 4 Å, DMF, 0 °C, 14 h, then 2,6-lutidine, TFAA, DME, −20 °C, 12 h, 85%. Supporting Information Supporting Information File

Strategies toward protecting group-free glycosylation through selective activation of the anomeric center

• A. Michael Downey and
• Michal Hocek

Beilstein J. Org. Chem. 2017, 13, 1239–1279, doi:10.3762/bjoc.13.123

• [97]. GlcNAc binding is shown as an example in Scheme 34. 4.4 Lawesson’s Reagent to form anomeric thiols Davis and co-workers described the use of Lawesson’s reagent for the synthesis of both protected and unprotected glycosyl thiols. The study demonstrated tremendous robustness in the synthesis of

• glycoproteins would be a tremendous advancement in the field. The major drawback, however, is that the authors did not isolate the purified glycoprotein; their yield is based solely on the ESIMS analysis of the crude reaction mixture. It is also known that Lawesson’s reagent is not compatible with a C2 NAc

Phosphorus pentasulfide mediated conversion of organic thiocyanates to thiols

• Chandra Kant Maurya,
• Avik Mazumder and
• Pradeep Kumar Gupta

Beilstein J. Org. Chem. 2017, 13, 1184–1188, doi:10.3762/bjoc.13.117

• reaction. Most importantly, the reaction furnished only thiols as the final product with no disulfide formation. Interestingly, no similar reaction of thiocyanates was observed with other thionating agents like Lawesson’s reagent and PSCl3 and the reactant was recovered quantitatively in those cases. In

N-Propargylamines: versatile building blocks in the construction of thiazole cores

• S. Arshadi,
• E. Vessally,
• L. Edjlali,
• R. Hosseinzadeh-Khanmiri and
• E. Ghorbani-Kalhor

Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61

• examples for the preparation of fully substituted dihydrothiazoles 46 through the treatment of N-propargylamides 45 with Lawesson’s reagent in toluene. It is suggested that the N-(propargyl)thioamide intermediate A is initially formed, followed by a facile 5-exo-dig cyclization process to give the final

• -propargylthioamide intermediate A. Synthesis of 5-(dibromomethyl)thiazoles 44 via halocyclization of N-propargylamines 43 described by Yarovenko. Synthesis of dihydrothiazoles 46 through the treatment of N-propargylamides 45 with Lawesson’s reagent. Synthesis of thiazoles 49 by treatment of silyl-protected N

A new and convenient synthetic way to 2-substituted thieno[2,3-b]indoles

• Roman A. Irgashev,
• Arseny A. Karmatsky,
• Gennady L. Rusinov and
• Valery N. Charushin

Beilstein J. Org. Chem. 2015, 11, 1000–1007, doi:10.3762/bjoc.11.112

• the starting materials, followed by treatment of the intermediate 3-(2-oxo-2-(hetero)arylethylidene)indolin-2-ones with Lawesson’s reagent. The latter process involves two sequential reactions, namely reduction of the C=C ethylidene double bond of the intermediate indolin-2-ones followed by the Paal

• –Knorr cyclization, thus affording tricyclic thieno[2,3-b]indoles. Keywords: aldol-crotonic condensation; isatin; Lawesson’s reagent; methyl ketones; Paal–Knorr reaction; thieno[2,3-b]indole; Introduction 8H-Thieno[2,3-b]indole is a fused heterocyclic system, which has attracted a considerable

• indolin-2-ones 11. Compounds 11 bearing the fragment of 4-oxobutyramides (1,4-dicarbonyl derivatives) can be cyclized into thieno[2,3-b]indoles by using the Paal–Knorr reaction with such thionation agents, as P4S10 or Lawesson’s reagent. This four-step route to thieno[2,3-b]indoles via the formation of

DNA display of glycoconjugates to emulate oligomeric interactions of glycans

• Alexandre Novoa and
• Nicolas Winssinger

Beilstein J. Org. Chem. 2015, 11, 707–719, doi:10.3762/bjoc.11.81

• ]. The first method reported was leveraged on a nucleophilic coupling between readily available glycosyl thiol (obtained in one step by treatment of a native carbohydrate with Lawesson’s reagent [37]) and a chloroacetamide-functionalized PNA (Scheme 7) [38][39]. Using this method, we have shown that

Bis(vinylenedithio)tetrathiafulvalene analogues of BEDT-TTF

• Erdal Ertas,
• İlknur Demirtas and
• Turan Ozturk

Beilstein J. Org. Chem. 2015, 11, 403–415, doi:10.3762/bjoc.11.46

• BEDT-TTF (ET) 3. It possesses a vinyl moiety at the peripheries in place of the ethylene group of ET. It can also be considered as a tetrathiafulvalene analogue having fused 1,4-dithiin rings as its peripheries. The synthesis was achieved through the reaction of a 1,8-diketone with Lawesson’s reagent

• of synthesizing fused 1,4-dithiin and thiophene ring systems, possessing functional groups such as Ph 4-MeOC6H4 and 4-O2NC6H4 (Scheme 1) [46]. The synthesis involved treatment of the diketone 6, produced through the reaction of the readily available dianion 5 [52] with α-haloketones, with Lawesson’s

• reagent 15 to obtain [1,3-dithiolo[4,5-b][1,4]dithiin-2-thione 11, which is an analogue of half ET, as a major product, and the thiophene 13 as a minor product. After employing different reaction conditions and an in depth study, we suggested that the reaction mechanism involves interaction of 6 with LR

Synthesis of new, highly luminescent bis(2,2’-bithiophen-5-yl) substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole

• Anastasia S. Kostyuchenko,
• Vyacheslav L.Yurpalov,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2014, 10, 1596–1602, doi:10.3762/bjoc.10.165

• with phosphorus oxychloride, in 78 and 83% yields, respectively. The reaction of 11 with a Lawesson’s reagent led to the formation of 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-tiadiazole (15, 70% yield) (Scheme 4). To the contrary, 3,5-bis(3-decyl-2,2'-bithiophen-5-yl)-4-phenyl-4H-1,2,4-triazole (18

Isocyanide-based multicomponent reactions towards cyclic constrained peptidomimetics

• Gijs Koopmanschap,
• Eelco Ruijter and
• Romano V.A. Orru

Beilstein J. Org. Chem. 2014, 10, 544–598, doi:10.3762/bjoc.10.50

• aldehydes and carboxylic acids [106]. Subsequent TFA-treatment provided the precursor 125 that via a follow-up reaction with Lawesson’s reagent and an intramolecular cyclization gave access to the thiazole derivative 126. A second TFA-cleavage of the N-(1,1,3,3-tetramethylbutyl) group resulted in the 5

Amyloid-β probes: Review of structure–activity and brain-kinetics relationships

• Todd J. Eckroat,
• Abdelrahman S. Mayhoub and
• Sylvie Garneau-Tsodikova

Beilstein J. Org. Chem. 2013, 9, 1012–1044, doi:10.3762/bjoc.9.116

• amide 69, which was subsequently converted to the thioamide by using Lawesson’s reagent and cyclized to form the benzothiazole core 70 (Scheme 6B). Demethylation with BBr3 and protection of the resulting hydroxy moiety as the methoxymethyl (MOM) ether gave 71. Reduction of the nitro group to 72

Appel-reagent-mediated transformation of glycosyl hemiacetal derivatives into thioglycosides and glycosyl thiols

• Tamashree Ghosh,
• Abhishek Santra and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 974–982, doi:10.3762/bjoc.9.112

• halide or acetate with thiourea or thioacetate and hydrolysis of the resulting intermediates [26][27]; (b) reaction of hydrogen sulfide gas with glycosyl halides in hydrogen fluoride [39]; (c) treatment of the glycosyl hemiacetal derivatives with Lawesson’s reagent [40] and (d) treatment of 1,6-anhydro

Imidazolinium and amidinium salts as Lewis acid organocatalysts

• Oksana Sereda,
• Nicole Clemens,
• Tatjana Heckel and
• René Wilhelm

Beilstein J. Org. Chem. 2012, 8, 1798–1803, doi:10.3762/bjoc.8.205

• , the model reaction shown in Scheme 2 was evaluated. The α,β-unsaturated thioester 5 was prepared from ethyl cinnamate and 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson’s reagent) [22]. The cycloaddition of ethyl thionocinnamate (5) with 1.5 equiv of cyclopentadiene (2

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• -immobilized β-ketoamides 121. The latter β-ketoamides 121, aryl- or alkylhydrazines and Lawesson’s reagent were suspended in a mixture of THF/Py and heated at 50–55 °C to afford resin-bound 5-aminopyrazoles 122. The free 5-aminopyrazoles 123 were liberated from the solid support by treatment with TFA (Scheme