Synthesis of (−)-julocrotine and a diversity oriented Ugi-approach to analogues and probes

• Ricardo A. W. Neves Filho,
• Bernhard Westermann and
• Ludger A. Wessjohann

Beilstein J. Org. Chem. 2011, 7, 1504–1507, doi:10.3762/bjoc.7.175

• , and melting point of 1 were consistent with the reported data [2][14][15]. For the diversity oriented synthesis the advanced intermediate 5 was used as the amino component in an Ugi-4CR with (S)-2-methylbutanoic acid, hydrophobic amino acids, formaldehyde and tert-butyl isocyanide (Scheme 2). These

• addition of (S)-2-methylbutanoic acid, Boc-Gly, Boc-Ala, Boc-Val, Boc-Leu, Boc-Phe and Boc-Ile and tert-butyl isocyanide. Following this procedure, the desired optically active compounds 6a–g were obtained in 55–63% yields. Their structures were confirmed by 1H, 13C NMR and HRMS spectra. Finally, the Ugi

Ugi post-condensation copper-triggered oxidative cascade towards pyrazoles

• Aurélie Dos Santos,
• Laurent El Kaim,
• Laurence Grimaud and
• Caroline Ronsseray

Beilstein J. Org. Chem. 2011, 7, 1310–1314, doi:10.3762/bjoc.7.153

• ; isocyanide; pyrazolidinone; Introduction In the last twenty years, the Ugi reaction coupled with its various post-condensations towards heterocyclic libraries has established the success of isocyanide-based multicomponent reactions [1][2][3][4][5][6][7]. Chemists in both academia and industry have taken

• MeOH under standard Ugi conditions, led to the formation of the amide 2a in 64% isolated yield. The compatibility of the hydrazone with this coupling is certainly due to the higher electrophilicity of the intermediate iminium. The latter traps the isocyanide before any interaction with the hydrazone

Multicomponent synthesis of artificial nucleases and their RNase and DNase activity

• Anton V. Gulevich,
• Lyudmila S. Koroleva,
• Olga V. Morozova,
• Valentina N. Bakhvalova,
• Vladimir N. Silnikov and
• Valentine G. Nenajdenko

Beilstein J. Org. Chem. 2011, 7, 1135–1140, doi:10.3762/bjoc.7.131

• activity of the new compounds towards single-stranded RNA and double-stranded circular DNA. Keywords: DNA; isocyanide; multicomponent reaction; organocatalysis; peptidomimetic; RNA; Introduction RNA cleavage can serve as a molecular tool for biological research [1], as well as for development of

• especially important because multicomponent reactions (MCR) could be adapted to a high throughput synthesis of libraries of compounds. It is known that isocyanide-based MCR are very efficient for synthesis of peptides and peptide molecules [19][20][21][22][23][24]. We proposed that the desired compounds 5

• ); 13C NMR (100 MHz, CDCl3) δ 155.6 (t, J = 5.9 Hz, NC), 41.1 (t, J = 6.6 Hz, (CH2CH2CH2NC)2), 28.5, 25.2; IR (cm−1) 2150 (NC); Anal. calcd for C8H12N2: C, 70.55; H, 8.88; found: C, 70.34; H, 8.62. General procedure for the synthesis of 4a–g The corresponding isocyanide 3 (3 mmol) and phenyl phosphinic

Novel synthesis of pseudopeptides bearing a difluoromethyl group by Ugi reaction and desulfanylation

• Jingjing Wu,
• Hui Li and
• Song Cao

Beilstein J. Org. Chem. 2011, 7, 1070–1074, doi:10.3762/bjoc.7.123

• out with Merck 60 (230–400 mesh) silica gel. General procedure for compounds 3a–m To a stirred amine (1 mmol), the aldehyde (1 mmol) was added in portions for about 5 min. The mixture was stirred for 30 min at rt. Then, the reaction mixture was heated to 60 °C, and isocyanide (1 mmol) and 2,2-difluoro

Long-range diastereoselectivity in Ugi reactions of 2-substituted dihydrobenzoxazepines

• Luca Banfi,
• Andrea Basso,
• Valentina Cerulli,
• Valeria Rocca and
• Renata Riva

Beilstein J. Org. Chem. 2011, 7, 976–979, doi:10.3762/bjoc.7.109

• reaction, despite the fact that the stereogenic centre is only γ to the imine carbon (1,4 relative induction). This is, to our knowledge, the first example of 1,4 asymmetric induction in an isocyanide based multicomponent reaction of chiral carbonyl compounds or imines, and the first example of

• diastereoselectivity (from 5.25:1 up to 9:1) is completely unprecedented for an isocyanide based multicomponent reaction. A slight increase in the dr was observed on passing from R1 = Me to bulkier R1 = iBu. On the other hand the structure and the nature of both isocyanides and carboxylic acids seem to have little

• position is strongly favored. In this situation (Figure 1), the substituent at C-2 should be quite far away from the site of isocyanide attack, being unable to discriminate the two diastereotopic faces. Thus, rationalization of the observed stereoselectivity is not trivial, also because we have not yet

Synthesis of dihydrophenanthridines by a sequence of Ugi-4CR and palladium- catalyzed intramolecular C-H functionalization

• Florence Bonnaterre,
• Michèle Bois-Choussy and
• Jieping Zhu

Beilstein J. Org. Chem. 2008, 4, No. 10, doi:10.3762/bjoc.4.10

• -functionalization reaction has proven to be an efficient strategy to increase the skeleton diversity. Results The Ugi reaction of an o-iodobenzaldehyde (2), an aniline (3), an isocyanide (4), and a carboxylic acid (5) afforded α-acetamido-α-phenylacetamide (6) in good to excellent yields. The palladium-catalyzed

• Scheme 1. The Ugi four-component reaction between an o-iodobenzaldehyde 2, an aniline 3, an isocyanide 4 and a carboxylic acid 5 should afford an α-acetamido-α-phenylacetamide 6, which upon palladium-catalyzed C-H activation process should provide dihydrophenanthridine 1 [15][16][17][18][19][20][21

• needed for the success of the cyclization. We report herein our results on the two-step synthesis of dihydrophenanthridines 1 [23]. Results and Discussion Reaction of o-iodobenzaldehyde (2a, R1 = H), aniline (3a, R2 = H), tert-butyl isocyanide (4a) and butyric acid (5a) in trifluoroethanol (TFE) at room

Aroylketene dithioacetal chemistry: facile synthesis of 4-aroyl- 3-methylsulfanyl- 2-tosylpyrroles from aroylketene dithioacetals and TosMIC

• H. Surya Prakash Rao and
• S. Sivakumar

Beilstein J. Org. Chem. 2007, 3, No. 31, doi:10.1186/1860-5397-3-31

• H. Surya Prakash Rao S. Sivakumar Department of Chemistry, Pondicherry University, Puducherry, 605 014, India 10.1186/1860-5397-3-31 Abstract The cycloaddition of the von Leusen's reagent (p-tolylsulfonyl)methyl isocyanide (TosMIC) to α-aroylketene dithioacetals (AKDTAs) in the presence of sodium

• heterocyclic systems, examples of their participation in the cycloaddition reactions are rare. In continuation of our interest on ketene acetals [5][6][7] we considered that 1,3-dipolar cycloaddition of the anion generated from the von Leusen's reagent (p-tolylsulfonyl)methyl isocyanide (TosMIC) 2 to AKDTAs 1