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

• depends on the choice of potential reaction partners, but also on its substitution pattern and the reaction conditions. As examples, when N1 is substituted with a methyl group, the carbene can be trapped by elemental sulfur, isocyanates, and isothiocyanates which form indazolethione 4, indazolium-3

The rapid generation of isothiocyanates in flow

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 1613–1619, doi:10.3762/bjoc.9.184

• Marcus Baumann Ian R. Baxendale Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, United Kingdom 10.3762/bjoc.9.184 Abstract Isothiocyanates are versatile starting materials for a wide range of chemical reactions. However, their high nucleophilic susceptibility means they

• are best prepared and used immediately. We report here on a flow platform for the fast and efficient formation of isothiocyanates by the direct conversion of easily prepared chloroximes. To expedite this chemistry a flow insert cartridge containing two immobilised reagents is used to affect the

• which has received less attention are isothiocyanates. These species are widely utilised as valuable starting materials for many thiourea-based organocatalysts [24][25][26], numerous heterocyclic entities [27][28][29] as well as important entry points towards other key functional groups such as

End-labeled amino terminated monotelechelic glycopolymers generated by ROMP and Cu(I)-catalyzed azide–alkyne cycloaddition

• Ronald Okoth and
• Amit Basu

Beilstein J. Org. Chem. 2013, 9, 608–612, doi:10.3762/bjoc.9.66

• accomplished by amidation with an azido-amine linker followed by Cu(I)-catalyzed azide–alkyne cycloaddition with propargyl sugars. Subsequent Teoc deprotection and conjugation with pyrenyl isothiocyanates afforded well-defined end-labeled glycopolymers. Keywords: capping agent; carbohydrate; glycan; olefin

New simple synthesis of ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thiones: Direct formation from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles

• Qiuping Ding,
• Yuqing Lin,
• Guangni Ding,
• Fumin Liao,
• Xiaoyan Sang and
• Yi-Yuan Peng

Beilstein J. Org. Chem. 2013, 9, 460–466, doi:10.3762/bjoc.9.49

• or isothiocyanates bearing one o-substituted α,β-unsaturated carbonyl fragment promoted by the CS2/TBAF system [17]. However, both the low yields (30–60%) of the products and the substrate limitations outweigh their advantages. As part of a continuing effort in our laboratory toward the development

Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

• Pankaj Chauhan and
• Swapandeep Singh Chimni

Beilstein J. Org. Chem. 2012, 8, 2132–2141, doi:10.3762/bjoc.8.240

• grinding and liquid-assisted grinding (LAG) have been applied to the synthesis of mono- and bis(thiourea)s in quantitative yield by using the click coupling of aromatic or aliphatic diamines with aromatic isothiocyanates (Scheme 9) [54]. The mechanochemically prepared chiral molecules were applied as

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

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

• in the strict sense of the term, i.e. we shall not be concerned with tris- and higher oligoallenes, which have also been reported occasionally. Heteroanalogues of the bisallenes such as ketenes [15] or isothiocyanates [16] will not be dealt with either, even if they contain one “intact” allene group

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

• a very straightforward approach: Enantiopure (S)-S-methyl-S-phenylsulfoximine [(S)-2] was added to 3,5-bis(trifluoromethyl)phenyl isothiocyanate to provide product (S)-3 (Scheme 1). This kind of addition was first described by Wehr in 1965 who allowed a number of isothiocyanates to react with

• [35][59][60], two isothiocyanates, namely phenyl isothiocyanate and 3,5-bis(trifluoromethyl)phenyl isothiocyanate, were added. Both thiourea formations went very well, and the desired products (S)-12 and (S)-13 were obtained in almost quantitative yields (98% and 99%, respectively). In (S)-12 and (S

• must then be considered and serve as guideline. Conclusion In summary, we introduced enantiopure sulfoximines to the field of organocatalysis. The present work demonstrates that the addition of phenyl isothiocyanates to suitable amino-functionalized sulfoximines or to the sulfoximine nitrogen itself

Highly enantioselective access to cannabinoid-type tricyles by organocatalytic Diels–Alder reactions

• Stefan Bräse,
• Nicole Volz,
• Franziska Gläser and
• Martin Nieger

Beilstein J. Org. Chem. 2012, 8, 1385–1392, doi:10.3762/bjoc.8.160

• )phenyl)thiourea, which gave a satisfying 60% yield. In order to optimize the yield and to introduce chiral elements, we screened a number of analogues. These thiourea catalysts 9a–l were easy to obtain from the corresponding isothiocyanates 7a,b and chiral amines 8a–f in a one-step synthesis (Scheme 1

A general and facile one-pot process of isothiocyanates from amines under aqueous conditions

• Nan Sun,
• Bin Li,
• Jianping Shao,
• Weimin Mo,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2012, 8, 61–70, doi:10.3762/bjoc.8.6

• Academy of Sciences, Lanzhou 730000, China 10.3762/bjoc.8.6 Abstract A general and facile one-pot protocol for the preparation of a broad range of alkyl and aryl isothiocyanates has been developed from their corresponding primary amines under aqueous conditions. This synthetic process involves an in situ

• particularly for highly electron-deficient substrates. This novel and economical method is suitable for scale-up activities. Keywords: aqueous conditions; cyanuric acid; isothiocyanates; one-pot process; organic synthesis; primary amines; Introduction Isothiocyanates are a class of heteroallenic compounds

• which are abundant in many cruciferous vegetables. Recently, it has been found that naturally occurring isothiocyanates play a significant role in the cancer chemopreventive activity of these plant species [1][2], and thus, many of such analogues containing the isothiocyanate motif have been synthesized

A new and facile synthetic approach to substituted 2-thioxoquinazolin-4-ones by the annulation of a pyrimidine derivative

• Nimalini D. Moirangthem and
• Warjeet S. Laitonjam

Beilstein J. Org. Chem. 2010, 6, 1056–1060, doi:10.3762/bjoc.6.120

• -one libraries by solid-phase synthesis has been reported [19][20][21]. There are two approaches for the solution-phase parallel synthesis of 2-thioxoquinazolin-4-ones [22]. The first approach is based on the reaction of methyl anthranilates with isothiocyanates in refluxing pyridine or DMF. The second

(Pseudo)amide-linked oligosaccharide mimetics: molecular recognition and supramolecular properties

• José L. Jiménez Blanco,
• Fernando Ortega-Caballero,
• Carmen Ortiz Mellet and
• José M. García Fernández

Beilstein J. Org. Chem. 2010, 6, No. 20, doi:10.3762/bjoc.6.20

• followed by treatment with yellow mercury (II) oxide [68]. There are two general strategies to access pseudoamide-type oligosaccharide mimics: i) nucleophilic addition of sugar derivatives to carbohydrate isocyanates, isothiocyanates or isocyanides; and ii) conversion of sugar azides into glycosyl