New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• directionality that might make these interactions of a great value to the field of organocatalysis [71][72][73]. Molecular iodine has been used for many decades as a mild catalyst or promoter of various organic transformations such as conjugate addition, imine formation or aldolate dehydration reactions [74][75

• ][76][77][78][79]. Interestingly, such reaction mechanisms are not well understood, and the formation of trace quantities of hydroiodic acid rather than the direct substrate activation by molecular iodine has been frequently invoked to rationalize the outcome of these studies. Recently, Breugst and co

• -workers have re-evaluated the molecular iodine-catalyzed conjugate addition to α,β-unsaturated carbonyls or nitrostyrenes (Scheme 14) [80]. Based on their computational studies, they proposed that iodine activates the enone moiety by forming a halogen bond with the carbonyl and thus forming a more

TBHP-mediated highly efficient dehydrogenative cross-oxidative coupling of methylarenes with acetanilides

• Cui Chen,
• Weibing Liu and
• Peng Zhou

Beilstein J. Org. Chem. 2016, 12, 2250–2255, doi:10.3762/bjoc.12.217

• reaction does not occur in the absence of molecular iodine (Table 1, entry 14), which indicates that molecular iodine is requisite for this conversion. We were pleased to find that an excellent product yield of 86% was obtained (Table 1, entry 15) when increasing the loading of TBHP to 3.0 equivalents

• by the formation of 3aa. Initially, toluene (1a) reacted with molecular iodine and TBHP to produce the 1-(iodomethyl)benzene (4) and benzaldehyde (5) [21][22]. Intermediate 6 was generated from the coupling of 2a with intermediate 4 [22], by eliminating a molecule of HI. According to the results of

C–H bond halogenation catalyzed or mediated by copper: an overview

• Wenyan Hao and
• Yunyun Liu

Beilstein J. Org. Chem. 2015, 11, 2132–2144, doi:10.3762/bjoc.11.230

• methylketones 75 in the presence of molecular iodine, respectively. The tandem transformation of a carbonyl acetalization and a iodination in sustainable ethylene glycol under mild heating provided a practical approach in the synthesis of useful protected α-haloketones (Scheme 25). Recently, Kakiuchi and co

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• , for example, molecular iodine, the Bu4NI/t-BuOOH system, organic iodine(III or V) compounds, bromides combined with oxidants, hypochlorite, and so on, acted as oxidants. The oxidative coupling of primary alcohols 130 with methanol or trifluoroethanol and the oxidative coupling of aldehydes 132 with

• structurally diverse alcohols 133 were performed using molecular iodine in the presence of potassium carbonate (Scheme 26) [127]. In the former case, methanol or trifluoroethanol served as the solvent. In the latter case, the reaction was carried out in tert-butanol; the amount alcohol was nearly equivalent

• commonly employed in the oxidative coupling of OH-reagents with carbonyl compounds. Methods were developed for the sulfonyloxylation of ketones, in which iodoarene is generated in situ by the iodination of arene with molecular iodine [183] or NH4I [184] in the presence of m-chloroperbenzoic acid. In the

A general metal-free approach for the stereoselective synthesis of C-glycals from unactivated alkynes

• Shekaraiah Devari,
• Manjeet Kumar,
• Ramesh Deshidi,
• Masood Rizvi and
• Bhahwal Ali Shah

Beilstein J. Org. Chem. 2014, 10, 2649–2653, doi:10.3762/bjoc.10.277

• , respectively, and with a high selectivity. The present results indicate the activation of terminal alkynes by TMSOTf forming trimethylsilylacetylenes [39]. In order to confirm the formation of trimethylsilylacetylenes, we attempted a control experiment involving the addition of molecular iodine instead of

Synthesis of α-amino amidines through molecular iodine-catalyzed three-component coupling of isocyanides, aldehydes and amines

• Praveen Reddy Adiyala,
• D. Chandrasekhar,
• Jeevak Sopanrao Kapure,
• Chada Narsimha Reddy and
• Ram Awatar Maurya

Beilstein J. Org. Chem. 2014, 10, 2065–2070, doi:10.3762/bjoc.10.214

• the synthesis of α-amino amidines has been developed using a molecular iodine-catalyzed three-component coupling reaction of isocyanides, amines, and aldehydes. The presented strategy offers the advantages of mild reaction conditions, low environmental impact, clean and simple methodology, high atom

• reaction, we carried out a model reaction of tert-butyl isocyanide (1 mmol), benzaldehyde (1 mmol), and aniline (2 mmol) using 5 mol % of molecular iodine in methanol (Table 1). The reaction worked well at ambient temperature and led to good yields of 4a. Among various solvents screened, methanol was found

• -amino amidines 4 [17]. Conclusion In conclusion, we have developed a simple and clean methodology for the synthesis of substituted α-amino amidines using a three-component coupling of isocyanide, aldehyde, and aromatic amines with molecular iodine as a catalyst. The current strategy provides elegant

Nonanebis(peroxoic acid): a stable peracid for oxidative bromination of aminoanthracene-9,10-dione

• Vilas Venunath Patil and
• Ganapati Subray Shankarling

Beilstein J. Org. Chem. 2014, 10, 921–928, doi:10.3762/bjoc.10.90

• , methanol and also with molecular iodine as a catalyst. These reactions have various disadvantages such as long reaction time (up to 24 h), high temperature (60 to 100 °C) and are accompanied by a mixture of mono- and dibromo products. The reaction performed in glacial acetic acid at 100 °C resulted in 76

Efficient synthesis of dihydropyrimidinones via a three-component Biginelli-type reaction of urea, alkylaldehyde and arylaldehyde

• Haijun Qu,
• Xuejian Li,
• Fan Mo and
• Xufeng Lin

Beilstein J. Org. Chem. 2013, 9, 2846–2851, doi:10.3762/bjoc.9.320

• Haijun Qu Xuejian Li Fan Mo Xufeng Lin Department of Chemistry, Zhejiang University, Hangzhou 310027, China 10.3762/bjoc.9.320 Abstract A one-pot three-component synthesis of dihydropyrimidinones via a molecular iodine-catalyzed tandem reaction of simple readily available mono-substituted urea

• developed to be carried out in the presence of a Lewis or protic acid. It is still highly valuable to develop new direct approaches for the efficient synthesis of DHPMs due to the continued importance of the dihydropyrimidinone core in organic and medicinal chemistry. Recently, molecular iodine has emerged

• as an inexpensive, low-toxic catalyst with moderate Lewis acidity and water-tolerance in organic chemistry [16]. Previously, we have developed some molecular iodine-catalyzed organic transformations [17][18][19][20][21], herein we describe the first molecular iodine-catalyzed one-pot three-component

Short synthesis of the common trisaccharide core of kankanose and kankanoside isolated from Cistanche tubulosa

• Goutam Guchhait and
• Anup Kumar Misra

Beilstein J. Org. Chem. 2013, 9, 705–709, doi:10.3762/bjoc.9.80

• glycosyl acceptors with two hydroxy groups; (b) application of molecular iodine to the functional group transformations [13]; and (c) activation of the glycosyl trichloroacetimidate derivative by using nitrosyl tetrafluoroborate (NOBF4) [14]. The treatment of D-glucose pentaacetate with 2-phenylethanol in

• presence of molecular iodine [13] furnished compound 5 in 86% yield. Regioselective 3-O-glycosylation of compound 5 with L-rhamnose derived trichloroacetimidate derivative 3 [11] in the presence of NOBF4 [14] followed by acetylation in the same pot furnished disaccharide derivative 6 in 76% yield. In this

• was filtered and concentrated under reduced pressure. To a solution of the deacetylated product (3.1 g) in CH3CN (10 mL) was added benzaldehyde dimethylacetal (2.5 mL, 16.65 mmol) followed by molecular iodine (0.3 g, 1.18 mmol), and the reaction mixture was stirred at room temperature for 1.5 h. The

Tricyclic flavonoids with 1,3-dithiolium substructure

• Lucian G. Bahrin,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2012, 8, 1999–2003, doi:10.3762/bjoc.8.226

• in good to excellent yields (60–80%). Attempts to cyclize N,N-dialkyldithiocarbamates 6g and 6h by using the above-mentioned or other common cyclization agents, according to the literature [25][26][27], led to degradation of the substrates, often accompanied by loss of molecular iodine. A literature

A novel asymmetric synthesis of cinacalcet hydrochloride

• Veera R. Arava,
• Laxminarasimhulu Gorentla and
• Pramod K. Dubey

Beilstein J. Org. Chem. 2012, 8, 1366–1373, doi:10.3762/bjoc.8.158

• simply by heating 12 in 48% aqueous HBr solution under reflux for 15 h. The obtained crude was purified by passing it through a silica gel plug with n-hexane to afford 5 in 82% yield. Iodide 6 was prepared by reacting 12 with molecular iodine in the presence of triphenylphosphine and imidazole in CH2Cl2

When gold can do what iodine cannot do: A critical comparison

• Sara Hummel and
• Stefan F. Kirsch

Beilstein J. Org. Chem. 2011, 7, 847–859, doi:10.3762/bjoc.7.97

• the alkyne, and induce nucleophilic attack by the alkene (Scheme 12b). In this variant, molecular iodine coordinates first with the alkyne 40 analogous to the activation using gold to form an iodonium ion, after which the cyclization proceeds as before to give the final product 42 containing iodine

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

• ]arene sulfonates [20] or molecular iodine [21][22] as catalysts. In 2005 Beller et al. systematically tested the activity of various Lewis- and Brønsted acids in FC benzylations. They found that late transition metals such as HAuCl4 [23], IrCl3, [MesW(CO)3], RhCl3, H2PdCl4, H2PtCl6 [24] and FeCl3 [25

• ], polymolybdophosphoric acid supported silica [99], TsOH [100], FeCl3 [101][102], BiCl3 [103], Sc(OTf)3 [104] other Ru- or [105][106][107], Re-complexes [108] and even molecular iodine [109]. Toste and co-workers developed a mild rhenium-catalyzed propargylation of electron-rich arenes. In addition to principal method

Trifluoromethyl ethers – synthesis and properties of an unusual substituent

• Frédéric R. Leroux,
• Baptiste Manteau,
• Jean-Pierre Vors and
• Sergiy Pazenok

Beilstein J. Org. Chem. 2008, 4, No. 13, doi:10.3762/bjoc.4.13

• potassium tert-butoxide (KOR) in tetrahydrofuran at −100 °C. Upon trapping with molecular iodine, 3-iodo-4-trifluoromethoxybiphenyl was isolated in 90% yield [73]. Under the same conditions as employed with trifluoromethoxybenzene, 1- and 2-trifluoromethoxynaphthalene undergo selective lithiation at the 2