SbCl₃-catalyzed one-pot synthesis of 4,4′-diaminotriarylmethanes under solvent-free conditions: Synthesis, characterization, and DFT studies

• Ghasem Rezanejade Bardajee

Beilstein J. Org. Chem. 2011, 7, 135–144, doi:10.3762/bjoc.7.19

• the reaction can be summarized as a tandem regioselective electrophilic aromatic substitution reaction of N,N-dimethylaniline and aldehydes, in which SbCl3 (as a Lewis acid catalyst) activates the carbonyl group of the aldehydes. If we accept this mechanism, one can expect a general influence of

Kinetics and mechanism of vanadium catalysed asymmetric cyanohydrin synthesis in propylene carbonate

• Michael North and
• Marta Omedes-Pujol

Beilstein J. Org. Chem. 2010, 6, 1043–1055, doi:10.3762/bjoc.6.119

• established that the asymmetric addition of TMSCN to aldehydes can be catalysed by both Lewis acids and Lewis bases [1]. A Lewis acid catalyst activates the aldehyde by formation of an aldehyde-Lewis acid complex (e.g., 4) whilst a Lewis base catalyst activates the TMSCN through formation of a hypervalent

• position of the aldehyde during the transition state, and hence that complex 1 functioned predominantly as a Lewis acid catalyst, activating the aldehyde towards attack by cyanide, and resulting in more charge transfer to the benzylic position of the aldehyde during the transition state for formation of

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• mol% Mo(CO)6 as the Lewis acid catalyst under the strict exclusion of air and moisture, the Fukuzawa group utilized Sc(OTf)3 as a water and air tolerant catalyst. Various arenes, including benzene, p-xylene, or mesitylenes were alkylated with benzyl alcohols 4 to afford the desired 1,1-diarylalkanes 5

• (Scheme 12) [49]. Recently, Cozzi et al. showed that FC benzylations can proceed even without adding a Lewis acid catalyst, just “on water” at 80 °C. However, this method is restricted to reactive heteroarenes such as indole (30), pyrrole and nucleophiles including azides or acetylacetonates. Moreover

• reduction [121]. The same authors reported shortly after their initial finding a highly efficient substitution of ferrocenyl alcohols in water, without the need of any Lewis-acid catalyst [50]. A comparable, non-chiral version of this C–C bond forming reaction using ceric ammonium nitrate has recently been

DBFOX- Ph/metal complexes: Evaluation as catalysts for enantioselective fluorination of 3-(2-arylacetyl)-2-thiazolidinones

• Takehisa Ishimaru,
• Norio Shibata,
• Dhande Sudhakar Reddy,
• Takao Horikawa,
• Shuichi Nakamura and
• Takeshi Toru

Beilstein J. Org. Chem. 2008, 4, No. 16, doi:10.3762/bjoc.4.16

• with moderate to good enantioselectivities (up to 78% ee) when the reaction was carried out in the presence of DBFOX-Ph (11 mol%), Ni(ClO4)2·6H2O (10 mol%) and 2,6-lutidine (0 or 1.0 equiv) in CH2Cl2. Keywords: fluorination; enantioselective; nickel; Lewis acid; catalyst; Background Enantioselective

The first organocatalytic carbonyl- ene reaction: isomerisation- free C-C bond formations catalysed by H-bonding thio- ureas

• Matthew L. Clarke,
• Charlotte E. S. Jones and
• Marcia B. France

Beilstein J. Org. Chem. 2007, 3, No. 24, doi:10.1186/1860-5397-3-24

• Lewis acid catalyst. [1][2][3][4] One of the drawbacks of the intermolecular carbonyl ene reaction is substrate scope. The majority of all successful catalytic ene reactions have utilised the highly activated glyoxylate esters as enophile. Extending asymmetric intramolecular carbonyl ene reactions to

Asymmetric aza-Diels- Alder reaction of Danishefsky's diene with imines in a chiral reaction medium

• Bruce Pégot,
• Olivier Nguyen Van Buu,
• Didier Gori and
• Giang Vo-Thanh

Beilstein J. Org. Chem. 2006, 2, No. 18, doi:10.1186/1860-5397-2-18

• Danishefsky's diene in chiral ionic liquids provides the corresponding cycloadduct with moderate to high diastereoselectivity. The reaction has proved to perform better at room temperature in ionic liquids without either Lewis acid catalyst or organic solvent. Chiral ionic liquids are recycled while their

• highly efficient procedure for the synthesis of 2-substituted-2,3-dihydro-4-pyridone derivatives through the aza-Diels-Alder reaction under 'green chemistry' conditions. The reaction has been found to perform well at room temperature in ionic liquids using no Lewis acid catalyst or organic solvent.[30

• solvent-free microwave activation. All aza-Diels-Alder reactions were performed under argon at room temperature without either a Lewis acid catalyst or organic solvent (Table 1). As illustrated in Table 1, both yield and diastereoselectivity are highest when performing the experiment with 2 equivalents of

An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via indium- catalyzed multi- component domino reaction

• Dipak Prajapati and
• Mukut Gohain

Beilstein J. Org. Chem. 2006, 2, No. 11, doi:10.1186/1860-5397-2-11

• Mukaiyama Aldol reactions, Friedel-Crafts acylations,[6] Pavarob reactions[7] and Diels-Alder reactions[8] in water. Since the work of Loh,[8] indium halide has also been shown to be an effective Lewis acid catalyst for various reactions in aqueous media. [9][10] However, its use in the hetero Diels-Alder

High stereoselectivity on low temperature Diels- Alder reactions

• Luiz Carlos da Silva Filho,
• Valdemar Lacerda Júnior,
• Mauricio Gomes Constantino,
• Gil Valdo José da Silva and
• Paulo Roberto Invernize

Beilstein J. Org. Chem. 2005, 1, No. 14, doi:10.1186/1860-5397-1-14

• , Brazil 10.1186/1860-5397-1-14 Abstract We have found that some of the usually poor dienophiles (2-cycloenones) can undergo Diels-Alder reaction at -78°C with unusually high stereoselectivity in the presence of niobium pentachloride as a Lewis acid catalyst. A remarkable difference in reaction rates for

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• acid catalyst such as ytterbium triflate, revealed unsuccessful, only leading to recover the starting material. To overcome this difficulty, we turned to a more electrophilic sulfate moiety [36] (Scheme 3). Thus, treatment of the cis-diols 3 and 4 with thionyl chloride in the presence of triethylamine

• and 2 the cis-epoxide 7 or 8 has been isolated as a single stereoisomer. However, all attempts to open the epoxide ring involving various nucleophiles, sodium azide, benzylamine, n-butylamine, or serinol in different experimental conditions, protic or aprotic solvent, presence or absence of a Lewis