Copper-catalyzed asymmetric conjugate addition of organometallic reagents to extended Michael acceptors

• Thibault E. Schmid,
• Sammy Drissi-Amraoui,
• Christophe Crévisy,
• Olivier Baslé and
• Marc Mauduit

Beilstein J. Org. Chem. 2015, 11, 2418–2434, doi:10.3762/bjoc.11.263

• converted to the spiro compounds 62 and 63 (Scheme 17). The same protocol was later applied to conjugated enynones featuring additional unsaturated units and a total regioselectivity towards the 1,4-adducts was recorded under the standard conditions (Scheme 17) [36]. The chiral polyconjugated products (64

Synthesis of a tricyclic lactam via Beckmann rearrangement and ring-rearrangement metathesis as key steps

• Sambasivarao Kotha,
• Ongolu Ravikumar and
• Jadab Majhi

Beilstein J. Org. Chem. 2015, 11, 1503–1508, doi:10.3762/bjoc.11.163

• -caprolactam from cyclohexanone oxime involving the BR. The activation energy for the BR is almost the same as that of the nucleophilic substitution at sp2 nitrogen. To synthesize various aza-arenes and cyclic imines, such as quinolines, aza-spiro compounds and dihydropyrroles, the intramolecular SN2-type

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

• presence of peaks at 197.5 and 197.8 ppm, assigned to two carbonyl groups. This eliminated the substituent pattern as defined by spiro compounds 12–16. The C-allylated product 23 was evidenced by analysis of the HMBC spectrum which showed a strong 3-bond correlation between the C2 spiro carbon and the

• red diindolone heterocycles 7–10 were already produced, an indication of the ease of the cascade processes. After 1 h reaction time, there was no evidence for the presence of the monoallylindigo products, and the spiro compounds were present in minor quantities. Instead, a greater proportion of the

• red diindolones was produced. After 3 h reaction time the spiro compounds 12–16 and azepinodiindolones 17–18 predominate with a corresponding loss of the monoallylindigos and diindolones. This includes the more sterically demanding cinnamyl bromide and 1-bromo-2-butene which also gave rise to spiro

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• was treated with the Tebbe reagent, the dimer 23 was produced, presumably through a Cope reaction of the intermediately generated isomer 22. The bis-indene derivative 23 can be alkylated with 1,2-dibromoethane to produce a 1:1 mixture of the spiro compounds 24 and 25. Although 9 could be reductively

One-pot four-component reaction for convenient synthesis of functionalized 1-benzamidospiro[indoline-3,4'-pyridines]

• Chao Wang,
• Yan-Hong Jiang and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2014, 10, 2671–2676, doi:10.3762/bjoc.10.281

• -substituted spiro[indoline-3,4’-pyridine]. It should be noted that pure products can be obtained by washing the formed precipitates from the reaction solution and no further purification process is needed. The similar reactions with ethyl cyanoacetate also produced the spiro compounds 1e–i in 68–74% (Table 1

Stereocontrolled synthesis of 5-azaspiro[2.3]hexane derivatives as conformationally “frozen” analogues of L-glutamic acid

• Beatrice Bechi,
• David Amantini,
• Cristina Tintori,
• Maurizio Botta and
• Romano di Fabio

Beilstein J. Org. Chem. 2014, 10, 1114–1120, doi:10.3762/bjoc.10.110

• rotation around the C3–C4 bond present in the azetidine derivative Ia by incorporating an appropriate spiro moiety. The cyclopropyl moiety was introduced by a diastereoselective rhodium catalyzed cyclopropanation reaction. Keywords: Amino acids; carbenes; cyclopropanation; rhodium; spiro compounds

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

• crystal X-ray analysis of one of the E-isomers, which equilibrate in solution as well as in the solid state. Heating of the indazole–indole spiro compounds results in the formation of quinazolines by a ring-cleavage/ring-closure sequence (X-ray analysis). Results of DFT calculations are presented

• CDCl3, respectively, as well as two different phenyl rings. The methyl groups of the isomeric spiro compounds 14a,c,d appear at δ = 3.74 ppm and – as overlapped signal – at δ = 2.60 ppm in the 1H NMR spectra measured in CDCl3. On conversion of the exocyclic imine groups from the Z- into the E

• chemistry of its own which differs from the chemistry of N-heterocyclic carbenes of other ring systems. At low temperatures it can be trapped as a rhodium complex. Without trapping reagents it dimerizes under ring-cleavage to form two isomeric spiro compounds possessing E- and Z-configurated methylimine

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

Four-component reaction of cyclic amines, 2-aminobenzothiazole, aromatic aldehydes and acetylenedicarboxylate

• Hong Gao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 2934–2939, doi:10.3762/bjoc.9.330

• spiro compounds by using the in situ generated Huisgen 1,4-dipoles [17][18][19][20][21][22][23][24]. During these research works, we noticed that even through the cyclic secondary amines such as pyrrolidine, piperidine and morpholine also reacted with electron-deficient alkynes to give the Huisgen 1,4

Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

• Verena Weidmann,
• Mathias Schaffrath,
• Holger Zorn,
• Julia Rehbein and
• Wolfgang Maison

Beilstein J. Org. Chem. 2013, 9, 2233–2241, doi:10.3762/bjoc.9.262

• is a suitable method to predict at least relative BDH-values of C–H bonds of the spiro compounds at hand. In absolute terms, B3LYP underestimates the BDH systematically by 2.9–4.6 kcal/mol. The experimental observation as summarized in Scheme 3, e.g., the selective oxidation in 2-position of an allyl

• that a BHD298 of around 80 kcal/mol (CBS-QB3) seems to be a threshold that might be used as a guideline to decide whether an allylic oxidation of spiro compounds related to 11 and 12 with PSA takes places or not. As a further test on the substrate scope of the reaction, we were interested in the

Facile synthesis of functionalized spiro[indoline-3,2'-oxiran]-2-ones by Darzens reaction

• Qin Fu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 918–924, doi:10.3762/bjoc.9.105

• structures of the spiro compounds 5a–p were also established by spectroscopic methods and were confirmed by single-crystal X-ray structure determination of compound 5o (Figure 3). 1H NMR spectra showed that a mixture of cis/trans isomers existed in most samples with a large range of different cis/trans

Synthesis of functionalized spiro[indoline-3,4’-pyridines] and spiro[indoline-3,4’-pyridinones] via one-pot four-component reactions

• Li-Juan Zhang,
• Qun Wu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 846–851, doi:10.3762/bjoc.9.97

• structures of the prepared spiro[indoline-3,4’-pyridines] 1a–1p were fully characterized by spectroscopic methods and were further confirmed by the determination of the single crystal structures of the spiro compounds 1c (Figure 1) and 1h (Figure 2). When ethyl cyanoacetate was utilized in the domino

• [indoline-3,4’-pyridinones] 3. Benzylamine and 2-phenylethylamine could also be used in the domino reactions to give the spiro[indoline-3,4’-pyridinones] 3k–3n as the main products (Table 2, entries 19–22). The structures of the prepared spiro compounds 2a–2h and 3a–3n were fully established by

• spectroscopic methods. The single-crystal structures of spiro compounds 2b (Figure 3) and 3b (Figure 4) were successfully determined by X-ray diffraction methods. It should be pointed out that the 1H NMR spectra of compounds 2a–2h showed some distinguishing features. The characteristic resonance of the NH2

Synthesis of 2,3-dihydronaphtho[2,3-d][1,3]thiazole-4,9-diones and 2,3-dihydroanthra[2,3-d][1,3]thiazole-4,11-diones and novel ring contraction and fusion reaction of 3H-spiro[1,3-thiazole-2,1'-cyclohexanes] into 2,3,4,5-tetrahydro-1H-carbazole-6,11-diones

• Lidia S. Konstantinova,
• Kirill A. Lysov,
• Ljudmila I. Souvorova and
• Oleg A. Rakitin

Beilstein J. Org. Chem. 2013, 9, 577–584, doi:10.3762/bjoc.9.62

• solution of spiro compounds 1d or 2d (1 mmol) and triethylamine (0.17 mL, 1.20 mmol) in chlorobenzene (20 mL) was heated under reflux for 12 h. The solvent was evaporated under reduced pressure, and the residue was crystallized from hexane/CH2Cl2 mixture. Retrosynthetic analysis of 2,3-dihydronaphtho[2,3-d

• ]carbazole-6,11-dione (15) and 5-methyl-2,3,4,5-tetrahydro-1H-naphtho[2,3-b]carbazole-6,13-dione (16). A plausible mechanism for the conversion of spiro compounds 1d or 2d into carbazolediones 15 and 16. Supporting Information Supporting Information File 134: Spectroscopic and analytical data

Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

• Yan Sun,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 8–14, doi:10.3762/bjoc.9.2

• be separated from the reaction system. On the other hand, the reaction of α-naphthylamine also gave good yields of spiro compound 1l (Table 1, entry 12). The structures of spiro compounds 1a–1l were fully characterized by 1H and 13C NMR, HRMS, and IR spectra and were further confirmed by a single

• -crystal X-ray diffraction study performed for the compound 1b (Figure 1). It should be pointed out that the structure of the obtained spiro compounds is very interesting, in which the oxindole was connected to the ortho-position of the amino group of arylamine. It is well known that the one-pot reactions

• -substituent afforded solely spiro[dihydropyridine-oxindole] 1a–1l in satisfactory yields. Trying to increase the yields of spiro compounds and decrease the yields of condensation products was not successful. Both the spiro compounds 2a–2g and condensation products 3a–3d have low solubility in common organic

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• )-catalyzed opening of the VCP moiety embedded in an azapolycyclic system occurs at high temperature (110–130 °C) to afford the corresponding 1,3-dienes in moderate yield (34–53%). Keywords: nitrogen heterocycles; rearrangement; rhodium; small ring systems; spiro compounds; Introduction The cyclopropyl

A stable enol from a 6-substituted benzanthrone and its unexpected behaviour under acidic conditions

• Marc Debeaux,
• Kai Brandhorst,
• Peter G. Jones,
• Henning Hopf,
• Jörg Grunenberg,
• Wolfgang Kowalsky and
• Hans-Hermann Johannes

Beilstein J. Org. Chem. 2009, 5, No. 31, doi:10.3762/bjoc.5.31

• the reaction products is proposed and supported by DFT calculations. Keywords: consecutive reactions; intramolecular cyclization; molecular modelling; spiro compounds; X-ray structural analysis; Introduction Compounds for optoelectronic applications with electroluminescent (e.g. organic light