Iodine-catalyzed coupling of β-hydroxyketones with aromatic amines to form β-aminoketones and Benzo[h]quinolones

An iodine-catalyzed coupling of β-hydroxyketones with aromatic amines to yield β-aminoketones and benzo[h]quinolones had been developed. Noble metallic catalysts, oxidants, α, β-unsaturated ketone intermediates and aza-Michael addition were not involved in this coupling reaction which made it unique when compared to other reactions reported in literature. Inexpensive iodine catalyst, easy accessible raw materials, mild reaction conditions, good functional group tolerance and excellent selectivity made this coupling reaction be a practical method. This reaction can also be scaled up.     

Molecular iodine-catalyzed diastereoselective synthesis of cis-fused pyranobenzopyrans and furanobenzopyrans

A highly efficient method for the diastereoselective synthesis of cis-fused pyranobenzopyrans and furanobenzopyrans via 2 mol % of molecular iodine-catalyzed reaction of o-hydroxybenzaldimines with 3,4-dihydro-2H-pyran and 2,3-dihydrofuran at ambient temperature is described. 2-Butoxy-4-N-arylaminobenzopyrans were also synthesized from o-hydroxybenzaldimine and n-butyl vinyl ether using this procedure.     

Iodine-catalyzed aerobic oxidation of o-alkylazoarenes to 2H-indazoles

An iodine-catalyzed aerobic-oxidative C-H functionalization of o-alkylazoarenes to afford 2H-indazoles has been developed. CuI was found to be an effective additive to accelerate the regeneration of iodine in the catalytic cycle. This catalytic system is suitable for both electron-rich and electron-deficient azoarenes and tolerates a variety of functional groups with high yields. A gram-scale reaction was successfully conducted, proving the scalability of this reaction.     

Iodine-catalyzed direct allylation of chiral oxazolidinones by the amide-aldehyde-alkene condensation

An iodine-catalyzed direct allylation of chiral oxazolidinones with aldehydes and alkenes has been developed. The reaction proceeds, without use of any bases or metals, directly converted the 3-chiral oxazolidinones into N-allylated oxazolidinones. Additionally, the 3-chiral allylamine skeleton was constructed and the diastereomers were isolated by simple column chromatography.     

Iodine-catalyzed synthesis of 5-benzoyl-8H-phthalazino[1,2-b]quinazolin-8-one derivatives via a domino reaction involving a benzyl automatic oxidation by oxygen

A one-pot procedure for the synthesis of 5-benzoyl-8H-phthalazino[1,2-b]quinazolin-8-ones is achieved by an iodine-catalyzed reaction of 2-aminobenzohydrazides and 2-alkynylbenzaldehydes in good yields. The salient feature of this strategy is a domino type process including a condensation, addition, hydroamination, and a noteworthy benzyl automatic oxidation by oxygen under metal-catalyst-free conditions.     

Iodine-catalyzed C3-formylation of indoles using hexamethylenetetramine and air

An efficient iodine-catalyzed chemoselective 3-formylation of free (N–H) and N-substituted indoles was achieved by using hexamethylenetetramine (HMTA) in the presence of activated carbon under air atmosphere. This new method could provide 3-formylindoles in moderate to excellent yields with fairly short reaction times. Moreover, this catalytic formylation of indoles procedure can be applied to gram-scale synthesis.     

Regioselective synthesis of pyrano[3,2-f]quinoline and phenanthroline derivatives using molecular iodine

A series of polysubstituted pyrano[3,2-f]quinoline and phenanthroline derivatives have been synthesized by molecular iodine-catalyzed tandem reaction of various propargylic alcohols with or without substituted amines in excellent yields. Moreover, the cyclized side products are also pyrano[3,2-f]quinoline and phenanthroline derivatives.     

Formal [4 + 1] cycloaddition strategy for the synthesis of dihydrobenzofurans via Michael addition of 2-(2-nitrovinyl)-phenols and malonate esters (C1 synthon) and subsequent iodine-catalyzed oxidative annulation

A novel [4 + 1] cycloaddition protocol for the synthesis of dihydrobenzo(naphtho)furan skeletons from readily available 2-(2-nitrovinyl)-phen(naphth)ols and malonate esters via a tandem Michael addition/iodine-catalyzed oxidative annulation has been developed. This method provides a new and facile application of malonate esters as 1,1-nucleophilic/electrophilic type C1 synthons without a pre-functionalization step and the plausible reaction mechanism is proposed.     

Visible light-promoted,iodine-catalyzed selenoalkoxylation of olefins with diselenides and alcohols in the presence of hydrogen peroxide/air oxidant: an efficient access to <Emphasis Type="Italic">α</Emphasis>-alkoxyl selenides

Under iodine-catalyzed and visible light-irradiated aerobic conditions, selenoalkoxylation of olefins with diselenides and alcohols can be efficiently achieved to afford the useful α-alkoxyl selenides in the presence of only 0.5 equiv. of H₂O₂. Controlling the sub-stoichiometric H₂O₂ amount is crucial to avoid the non-selective over-oxidation of the diselenides that leads to the ineffective hyper-valent selenium compounds. Meanwhile, under visible light irradiation, the green, safe, and low-cost air can work as a supplemental mild oxidant in the reaction to ensure selective oxidation of the diselenides, full conversion of the reactants, and ultimately good yield of the products.     

Molecular iodine-catalyzed C3-alkylation of 4-hydroxycoumarins with secondary benzyl alcohols

A highly efficient method for the C-C bond formation via molecular iodine-catalyzed C3-alkylation reaction of 4-hydroxycoumarins with benzylic, benzhydrylic, allylic, and propargyl alcohols at 50 °C in MeNO₂ is described. The 3-alkylated-4-hydroxycoumarins were obtained in good yields (up to 97%). By applying this reaction as the key step, a multi-substituted pyranocoumarin can easily be synthesized in a one-pot procedure. The advantages of this method are broad scope, mild conditions, and easy handling since water is the only side product.     

Alkylation of 4,5-dihydro-1<Emphasis Type="Italic">H</Emphasis>-imidazole-2-thiol with iodomethylsilanes and -siloxanes

The alkylation of 4,5-dihydro-1H-imidazole-2-thiol with 1-iodomethyl(dimethyl)phenylsilane, 1-(iodomethyl)-1,1,3,3,3-pentamethyldisiloxane, and 1,3-bis(iodomethyl)-1,1,3,3-tetramethyldisiloxane involved iodine-catalyzed cleavage of the Si–C_sp ² and Si–O bonds with liberated (in situ) hydrogen iodide to afford 2-({[(4,5-dihydro-1H-imidazolium-2-ylsulfanyl)methyl]-1,1,3,3-tetramethyldisiloxanylmethyl}sulfanyl)-4,5-dihydro-1H-imidazolium di- and tetraiodides. Replacement of iodide ion in the products by triiodide gives new organosilicon ionic liquids with several charged fragments.     

碘作为Lewis酸催化剂在合成中的应用

碘催化的有机反应具有价廉易得、操作简单、温和、清洁、高效及高选择性等优点, 广泛应用于亲电反应、亲核反应、多组份反应以及其它涉及复杂官能团化合物的合成反应中, 在环境友好化学合成、复杂化合物合成及选择性合成领域具有应用价值.     

Iodine-catalyzed cycloalkenylation of dihydroquinolines and arylamines through a reaction with cyclic ketones under neat conditions

An iodine-catalyzed direct cycloalkenylation of dihydroquinolines and arylamines has been developed. This method consists of a Friedel–Crafts reaction between dihydroquinolines (or arylamines) and cyclic ketones in which the double bond is selectively generated throughout the course of the reaction resulting in a direct cycloalkenylation, under neat conditions.     

Synthesis of 6-aryl-5H-quinazolino[4,3-b]quinazolin-8(6H)-one derivatives in ionic liquids catalyzed by iodine

Research on Chemical Intermediates - The iodine-catalyzed reaction of 2-(2-aminophenyl)quinazolin-4(3H)-ones and benzaldehydes was treated in ionic liquids, giving a series of...     

Isocyanide based multicomponent reactions of oxazolidines and related systems

N-Alkyloxazolidines react in a multicomponent reaction with carboxylic acids and isocyanides to give N-acyloxyethylamino acid amides. The previously reported reaction conditions were improved using a design of experiments approach (DoE). Under the optimised conditions, good yields of the N-acyloxyethylamino acid amide products are obtained both via a three- or four-component approach from N-alkylethanolamines, aldehydes/ketones, isocyanides and carboxylic acids. The reaction of oxazolidines without a nitrogen substituent was found to give either the expected Ugi products or the N-acyloxyethylamino acid amides depending on the choice of reaction conditions. Optimised reaction conditions were also developed for the ring-expansion of oxazolidines to morpholin-2-ones via reaction with an isocyanide followed by hydrolysis. The mechanistic pathway of the multicomponent reaction was briefly investigated using an ¹⁸O labelling experiment. The carboxylic acid component can be replaced by a range of other acidic nucleophiles including thiobenzoic acid, thiophenol or 5-phenyltetrazole, which are incorporated via an alternative pathway. These latter reactions can also be applied to 2-aminotetrahydrofurans, 2-aminotetrahydropyrans or 4-hydroxybut-2-one, further extending the structural diversity of the multicomponent reaction products.     

Molecular iodine-catalyzed one-pot synthesis of substituted quinolines from imines and aldehydes

A mild, efficient, and general method for the synthesis of substituted quinolines via a molecular iodine-catalyzed one-pot domino reaction of imines with enolizable aldehydes has been described.     

Dual behavior of alcohols in iodine-catalyzed esterification under solvent-free reaction conditions

The dual behavior phenomenon of alcohols in iodine-catalyzed esterification under solvent-free reaction conditions (SFRCs) is described; the governing factor is the stability of the carbonium ion generated from the alcohol; high concentration reaction conditions (HCRCs) or dilute solutions are much less suitable. In the case of benzylic alcohols, loss of optical activity was noted, whereas alkyl alcohols furnished a product with retention of stereochemistry.     

Practical synthesis of blepharismone,a mating inducing pheromone of Blepharisma japonicum

Both enantiomers of blepharismone, a mating inducing pheromone produced by type II cells of Blepharisma japonicum, were synthesized via the Stille cross-coupling reaction of [4-(tert-butyl-dimethyl-silanyloxy)-2-trimethylstannanyl-phenyl]-carbamic acid tert-butyl ester with an acid chloride derived from (S)- and (R)-malic acid as a key reaction. The mating inducing activity of synthetic (S)-blepharismone was as effective as that of the natural one. The enantiomer (R)-blepharismone showed no mating inducing activity.     

Unusual reactivity of ortho-carbonylphenylboronic acids with diethanolamine

The reaction of carbonyl-substituted phenylboronic acids with diethanolamine has been investigated. For compounds containing carbonyl groups at the meta or para positions the reaction occurs exclusively at the boronic acid. Different reactivities were observed for ortho-substituted acetyl- and formylphenylboronic acids where the reaction occurred at both the boronic acid and at the carbonyl group. X-ray studies revealed the presence of a polycyclic structure with tetravalent boron and nitrogen atoms.     

A novel Barton decarboxylation produces a 1,4-phenyl radical rearrangement domino reaction

A novel 1,4-Phenyl radical rearrangement (1,4-PhRR) is described in a typical Barton decarboxylation procedure. While carrying out this reaction in presence of a N,N-disubstituted β-amino acid derivative, the decarboxyphenyl rearranged derivative is obtained, as well as in presence of β-N,N-acylamide. On the other hand, secondary amines give the β-lactam derivative without rearrangement, as well as N-Fmoc derivatives give the normal decarboxylation reaction. In regards of amines which are far away from the carboxylic group, such as δ-amino acid derivatives, the reaction occur through a typical Barton decarboxylation without rearrangement. The diversity of the reaction proves synthetic usefulness paving the way to interesting biologically active compounds.