One-pot nucleophilic substitution–double click reactions of biazides leading to functionalized bis(1,2,3-triazole) derivatives

• Hans-Ulrich Reissig and
• Fei Yu

Beilstein J. Org. Chem. 2023, 19, 1399–1407, doi:10.3762/bjoc.19.101

• reaction time and the fairly high amount of catalyst employed. As an alternative method, which should be more chemoselective, we examined the reduction with samarium diiodide [60]. This versatile one-electron transfer reagent is known to cleave N–O bonds with high selectivity [61][62] and was applied

• several times by our group with good success for reductive ring-openings of 1,2-oxazine derivatives [63][64]. A slight excess of samarium diiodide in tetrahydrofuran completely consumed compound 21 within five hours. Compound 26 was isolated in 50% yield, but again the sample was not clean. The NMR data

• reductive ring openings of bis(1,2,3-triazole) derivative 21 to divalent carbohydrate mimetics with hydrogen under palladium catalysis or with samarium diiodide did not proceed cleanly and need further optimization. Earlier approaches to multivalent carbohydrate mimetics B, D or F based on enantiopure

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• by a vinyl ketone (compound 135) or a butenolide (compound 137) moiety dramatically influenced the outcome of the reaction and no cycloadduct was observed in both cases (Scheme 27). 4 Radical cyclization (including SmI2) Introduced by Kagan more than four decades ago, samarium diiodide (SmI2) has

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• [16]. Based on their reactivity, major contributions in carbon-centered radical formation followed, consequently unlocking highly predictable intramolecular reactions, deoxygenation protocols (Barton–McCombie reaction) [17], etc. Other reagents that majorly contributed were samarium diiodide for the

• reduction of the amide using Wilkinson’s catalyst provided diastereoisomeric indole 131. Careful manipulation of the nitrile and alcohol side chains allowed selective cyclizations to the nitrogen atom of the indole core to conclude the total syntheses of 132–134. Samarium diiodide-mediated reductive

• , bipolamine I (176) was obtained from 169 via a samarium diiodide reduction of the mesylate, followed by sodium borohydride reduction of the ketone, hydroboration, and base-mediated cyclization. Flow-controlled divergent synthesis of aporphine and morphinandienone natural products (Felpin 2022) [92

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• have also been obtained (TiCl4/Zn [12][13][14][15][16][17] or TiCl3/Zn-Cu [18][19][20]), often as mixture of diastereomers. The use of samarium diiodide to achieve the pinacol coupling was not advised, since we had observed that intially formed ketyl radicals would add to the alkyne moiety [11], even

• on reaction with TiCl4/Zn/pyridine (27, Scheme 3) without cyclization. As before, the aldehyde had stayed in place. Interestingly, treatment of 25 with samarium diiodide afforded the primary alcohol and left the keto group unchanged. Still, no cyclization took place. One could think that endocyclic

Stereoselective synthesis of tricyclic compounds by intramolecular palladium-catalyzed addition of aryl iodides to carbonyl groups

• Jakub Saadi,
• Christoph Bentz,
• Kai Redies,
• Dieter Lentz,
• Reinhold Zimmer and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2016, 12, 1236–1242, doi:10.3762/bjoc.12.118

• reaction requires a reduction of palladium(II) back to palladium(0) which is apparently achieved by the present triethylamine. Keywords: 1,2-addition; aryl iodides; ketones; nucleophilic addition; palladium catalysis; Introduction For our systematic studies on samarium diiodide promoted cyclizations

Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms

• Tatjana Huber,
• Lara Weisheit and
• Thomas Magauer

Beilstein J. Org. Chem. 2015, 11, 2521–2539, doi:10.3762/bjoc.11.273

• silylation and oxidation afforded aldehyde 123. Next, the formation of the cyclobutanol ring was realized by an intramolecular samarium diiodide-mediated radical conjugate addition to afford tricycle 124 in 60% yield. Introduction of the dihydropyran ring of plumisclerin A (118) was envisioned to be carried

SmI₂-mediated dimerization of indolylbutenones and synthesis of the myxobacterial natural product indiacen B

• Nils Marsch,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2015, 11, 1700–1706, doi:10.3762/bjoc.11.184

• treatment of the indolylbutenone 5 with samarium diiodide in THF (formed from Sm and diiodoethane), the dimeric bisindolylcyclopentanes 6 (26%), 7 (27%) and a mixture of 8 and the open-chain dimer 9 (16%, 4:1) were isolated by semipreparative HPLC. The structures were elucidated by 2D NMR spectroscopy and

Diastereoselective and enantioselective conjugate addition reactions utilizing α,β-unsaturated amides and lactams

• Katherine M. Byrd

Beilstein J. Org. Chem. 2015, 11, 530–562, doi:10.3762/bjoc.11.60

• enantioselectivities when both electron-deficient and -rich anilines were added (Scheme 34). In 2008, Collin and co-workers developed the asymmetric aza-Michael addition of N-alkenoyloxazolidinones catalyzed by iodo(binaphtholato)samarium [243]. This group had previously reported the use of samarium diiodide in the

Synthesis of rigid p-terphenyl-linked carbohydrate mimetics

• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 1749–1758, doi:10.3762/bjoc.10.182

• -couplings to form biphenyl aminopyran or p-terphenyl-linked dimers. Hydrogenolysis afforded new unnatural aminosugar mimetics. Zinc in the presence of acid or samarium diiodide were examined for the N–O bond cleavage in order to obtain the rigid p-terphenyl-linked C-glycosyl dimers. Keywords: carbohydrate

• mimetics; hydrogenolysis; multivalent glycosystems; 1,2-oxazines; samarium diiodide; Suzuki cross-coupling; Introduction Carbohydrates are the class of biomolecules with the highest structural diversity [1][2]. Specific carbohydrates are responsible for cell-type specific interactions [3] and they are

• into 22 long reaction times were required and the high acidity led to the formation of side products. Nevertheless, the target compound 22 was isolated in a moderate yield of 59%. As a milder alternative, samarium diiodide was examined for the N–O bond cleavage [40][41][42][43][44][45]. With this

Development of an additive-controlled, SmI₂-mediated stereoselective sequence: Telescoped spirocyclisation, lactone reduction and Peterson elimination

• Brice Sautier,
• Karl D. Collins and
• David J. Procter

Beilstein J. Org. Chem. 2013, 9, 1443–1447, doi:10.3762/bjoc.9.163

• Peterson elimination. The approach allows functionalised cyclopentanols containing two vicinal quaternary stereocentres to be conveniently prepared from simple starting materials. Keywords: cyclisation; free radical; Peterson elimination; reduction; samarium; telescoped process; Introduction Samarium

• diiodide (SmI2) has become an essential tool for chemists since its introduction by Kagan [1][2], efficiently mediating a wide range of reductive transformations [3]. The reagent’s versatility and the high degree of control usually observed in SmI2-mediated reactions make it the first choice for an array

Copper(II)-salt-promoted oxidative ring-opening reactions of bicyclic cyclopropanol derivatives via radical pathways

• Eietsu Hasegawa,
• Minami Tateyama,
• Ryosuke Nagumo,
• Eiji Tayama and
• Hajime Iwamoto

Beilstein J. Org. Chem. 2013, 9, 1397–1406, doi:10.3762/bjoc.9.156

• hexenyl radical cyclization reactions [21], (Figure 1) [22][23][24][25][26][27][28][29][30]. For example, PET reactions of probe I with amines were observed to produce a spirocyclic ketone product while its reduction reaction induced by samarium diiodide (SmI2) gives rise to a cyclopropanol (left in

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Synthesis of chiral sulfoximine-based thioureas and their application in asymmetric organocatalysis

• Marcus Frings,
• Isabelle Thomé and
• Carsten Bolm

Beilstein J. Org. Chem. 2012, 8, 1443–1451, doi:10.3762/bjoc.8.164

• reduce the α-nitro group of (R)-7 to the corresponding amino substituent (as in (R)-8) failed [58]. None of the reductive conditions, which included (1) hydrogenation over palladium/charcoal, (2) applying samarium diiodide with methanol as proton source, and (3) using a combination of zinc powder with

Carbohydrate-auxiliary assisted preparation of enantiopure 1,2-oxazine derivatives and aminopolyols

• Marcin Jasiński,
• Dieter Lentz and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2012, 8, 662–674, doi:10.3762/bjoc.8.74

• samarium diiodide leading to enantiopure acyclic aminopolyols. We also report on our attempts to convert these compounds into enantiopure hydroxylated pyrrolidine derivatives. Keywords: aminopolyols; carbohydrates; chiral auxiliaries; lithiated alkoxyallenes; 1,2-oxazines; pyrroles; pyrrolidines; samarium

• samarium diiodide-induced reactions, are presented as well. Results and Discussion In continuation of our recent exploration of L-erythrose-derived nitrones for the synthesis of 3,6-dihydro-2H-1,2-oxazine derivatives [34], we turned our attention to benzaldehyde-derived nitrone 1a, which is readily

• type 12 contain a benzylamine substructure, standard methods that may possibly attack this moiety, such as catalytic hydrogenation, should be avoided. As an alternative, samarium diiodide is an attractive reagent for this purpose. Apart from its extraordinary potential for the formation of new carbon

Photocycloaddition of aromatic and aliphatic aldehydes to isoxazoles: Cycloaddition reactivity and stability studies

• Axel G. Griesbeck,
• Marco Franke,
• Jörg Neudörfl and
• Hidehiro Kotaka

Beilstein J. Org. Chem. 2011, 7, 127–134, doi:10.3762/bjoc.7.18

• , probably due to traces of acetic acid contained in the hydride reagent. Reductive treatment with sodium or samarium diiodide also led to decomposition of the photoproduct. Treatment of 9a with ethylmagnesium bromide did not lead to the alkylated photoproduct, but to partial decomposition into isoxazole 7e

Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations

• Jakub Saadi,
• Irene Brüdgam and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, 1229–1245, doi:10.3762/bjoc.6.141

• Jakub Saadi Irene Brudgam Hans-Ulrich Reissig Freie Universität Berlin, Institut für Chemie und Biochemie, Takustrasse 3, D-14195 Berlin, Germany 10.3762/bjoc.6.141 Abstract A series of γ-oxo esters suitably substituted with various styrene subunits was subjected to samarium diiodide-induced 8

• -trig cyclizations to cycloheptanol derivatives have been observed. In examples with high steric hindrance the ketyl–aryl coupling can be a competing process. Keywords: cyclooctanes; ketones; ketyls; medium-sized rings; samarium diiodide; single electron transfer; styrene derivatives; radicals

• ]. Among these approaches to carbocyclic compounds, samarium diiodide-mediated reactions play an important role and have been described in a number of excellent review articles [19][20][21] and original publications [22][23][24][25][26][27][28][29][30][31][32][33][34][35]. In our previous reports we have

Photosonochemical catalytic ring opening of α-epoxyketones

• Hamid R. Memarian and
• Ali Saffar-Teluri

Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2

• ] tribenzylamine (TBA) [20] and 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI) [22][23][24] or thermally induced single electron transfer by electron donating compounds such as samarium diiodide, [25] tributyltin hydride [26] and bis(cyclopentadienyl)titanium(III) chloride. [27] Ring opening reactions of epoxides