Samarium Triiodide–Catalyzed Formation of Mannich‐Type Products by Amidoalkylation of 1,3‐Dicarbonyl Compounds

With samarium triiodide (SmI₃) as a catalyst, the amidoalkylation of 1,3‐dicarbonyl compounds with N‐(1‐benzotriazol‐1‐ylalkyl)amides proceeded readily under mild conditions to afford Mannich‐type products in good to excellent yields.     

A Facile Route to Convert Acetylacetone into Other β-Diketones with Acyl Chlorides Promoted by Samarium Triiodide

Reaction of acetylacetone with acyl chlorides in the presence of SmI₃ gave β-diketones RCOCH₂COCH₃ (I) or RCOCH₂COR (II) in good yields under mild and neutral conditions.     

Synthesis of 1,3-Diketones by Reaction of α-Haloketones with Acyl Cyanides Promoted by Samarium Diiodide

α-Haloketones reacted with acyl cyanides to form 1,3-diketones in the presence of samarium diiodide. The reaction was assumed to proceed via a mechanism involving samarium enolates formed in situ from α-haloketones.     

One‐Pot Syntheses of Amides from N‐Acylation of Nitroarenes with Esters Mediated by Samarium Diiodide

Abstract

Mediated by samarium diiodide, various amides were prepared directly from nitroarenes and esters under mild conditions in a one‐pot procedure.     

Synthesis of Ketones from Acyl Chlorides and Triorganoindium Reagents by Pd‐Catalyzed Cross‐Coupling

Triorganoindium reagents prepared from indium tribromide and 3 equiv of organolithium reagents react with acyl chlorides in palladium‐catalyzed cross‐coupling for preparation of new ketones.     

β-Diketone Synthesis by Reaction of α-Haloketones with Acid Chlorides or Acid Anhydrides Promoted by Samarium Triiodide

Promoted by SmI₃, α-haloketones were reacted with acid chlorides or acid anhydrides and β-diketones were synthesized via intermediate samarium enolates.     

Efficient and Convenient Procedure for Preparation of N‐Sulfonylimines Catalyzed by Montmorillonite K‐10

A general and practical chemical route to the synthesis of N‐sulfonylimines using montmorillonite K‐10 as the catalyst is described. This method provides several advantages such as operational simplicity, short reaction time, using of inexpensive materials, noncorrosivity, lack of pollution, and high yields.     

Conformational Study of α‐N‐Acetyl‐D‐Neuraminic Acid by Density Functional Theory

The stable structures of α‐N‐acetyl‐D‐neuraminic acid (Neu5Acα) in the gas phase were studied at the B3LYP level of theory using 6‐31G(d,p) and 6‐31++G(d,p) basis sets. They are classified into five types according to the patterns of the intramolecular hydrogen bond formations. One of the stable structures had intramolecular hydrogen bond network of O₉H_O9 … O₈H_O8 … O?C₁‐O₁H_O1 and O₇H_O7…O?CHN‐C₅ similar to the crystal structure of Neu5Ac‐α‐methyl glycoside methyl ester. The stable structures of Neu5Acα are reasonable for the following sialooligosaccharide ligand studies with respect to the relationship between OH group orientations and intramolecular hydrogen bond formations. The barrier heights for isomerizations between the stable structures were computed to be 2.8 to 6.7 kcal/mol at the B3LYP/6‐31++G(d,p)//B3LYP/6‐31G(d,p) level, which are basic factors for the conformational behavior of Neu5Acα before its interactions with receptors. We also calculated Neu5Acα–4 or 5‐water complexes to take account of the solvent effect on the intramolecular hydrogen bonds in the stable structures. Consequently, the structures of Neu5Acα in the complexes are similar to each other, which is consistent with the known NMR data. Thus, the optimum Neu5Acα‐water complexes are some of the reasonable pseudohydrous Neu5Acα.     

Functionalized N‐Aryl‐Substituted Cyclens by Nucleophilic Aromatic Substitution

The reaction of trifold protected cyclen with fluorinated dinitroarenes yields aryl‐substituted or aryl‐bridged cyclen derivatives in good yield. The two arene nitro groups, necessary for the nucleophilic aromatic substitution, are subsequently selectively reduced to amines and further functionalized by amide formation. As an example, a cyclen derivative bearing a heterocyclic oligoamide with potential DNA binding ability was prepared.     

Introduction of N‐Containing Heterocycles into Pyrazole by Nucleophilic Aromatic Substitution

Abstract

The nucleophilic aromatic substitution on 5‐chloropyrazoles activated by the electron‐withdrawing formyl group offers a useful method to introduce a wide range of N‐containing heterocycles into them. The rate of reaction was greatly affected by the electronic nature of the N‐1 substitution.     

Synthesis and Properties of Surfactants derived from N‐Acetyl‐D‐Glucosamine

The synthesis of 2‐acetamido‐2‐deoxy‐6‐O‐octanoyl‐D‐glucono‐1,5‐lactone 9 and 2‐acetamido‐2‐deoxy‐6‐O‐octanoyl‐α‐D‐glucopyranose 7 from 2‐acetamido‐2‐deoxy‐α‐D‐glucopyranose is reported. For both targets, the key intermediate was allyl 2‐acetamido‐3,4‐di‐O‐benzyl‐2‐deoxy‐6‐O‐octanoyl‐α‐D‐glucopyranoside 5. Surface tension measurements (critical micellar concentration of 22.3 mM and 5 mM for 9 and 7, respectively) showed up the surface activity of both compounds, while enzyme inhibition assays indicated that 9 could inhibit bovine β‐N‐acetylglucosaminidase (K_i=6.5 µM) but not Serratia marcescens chitobiase nor hen egg‐white lysozyme. Moreover, 7 was shown to induce chitinase production of S. marcescens and to be readily metabolized by these bacteria.      

Efficient Synthesis of N,N′‐Disubstituted Ureas/Thioureas Catalyzed by Iodine

Iodine is an efficient catalyst for the synthesis of symmetrically N,N′‐disubstituted ureas/thioureas by heating respective amines or phenyl hydrazine and urea/thiourea on a preheated hot plate at 90–95°C, under solvent‐free conditions. The yields are excellent, and the reactions go to complete within 5–10 min.     

Aldol Condensation of β-Diketones and β-Ketoesters with Aldehydes Catalyzed by Samarium (III) Iodide

Catalyzed by SmI₃ β-diketones and β-ketoesters condense with aldehydes to give benzylidene substituted β-diketones and β-ketoesters at room temperatures in fair yields.     

Pd‐Catalyzed Synthesis of Biphenyls with Methylthio Group

The synthesis of unsymmetrical biaryls with a methylthio group is achieved using the air‐stable palladium–phosphinous acid complexes, [(t‐Bu)₂P(OH)]₂ PdCl₂ (POPd), as the catalyst. A great variety of substituted bromobenzenes having electron‐withdrawing and electron‐donating functional groups in para and meta positions have been successfully coupled with 3‐methylthiophenylboronic acid.     

Facile Allylation of N‐Boc and N‐Cbz Imines with Allyltrichlorosilane promoted by DMF

Facile allylation of various N‐Boc and N‐Cbz imines with allyltrichlorosilane has been effected using N,N‐dimethylformamide (DMF) as the activator. The N‐Boc and N‐Cbz homoallylic amines were obtained in good to high yields under mild conditions.     

Conjugate Addition of Indoles with Electron‐Deficient Olefins Catalyzed by Fe‐Exchanged Montmorillonite K10

Conjugate addition of indoles with a variety of electron‐deficient olefins in the presence of Fe‐exchanged montmorillonite K10 affords the corresponding Michael adduct in excellent yields with high selectivity. The catalyst was also found to be recyclable.     

Efficient Method for the Synthesis of 1,5‐Benzodiazepine Derivatives Catalyzed by Monoammonium Salt of 12‐Tungstophosphoric Acid

Monoammonium salt of 12‐tungstophosphoric acid [(NH₄)H₂PW₁₂O₄₀] was found to be a practical, inexpensive, reusable, and efficient heterogeneous catalyst for the preparation of 1,5‐benzodiazepine derivatives of o‐phenylenediamine and ketones. The heteropolyacid‐based catalyst has the advantages of simple workup procedure, water insolubility with good activity, and high‐yielding reaction for the synthesis of 1,5‐benzodiazepine derivatives.     

Synthesis of C‐Glycosyl Phosphate and Phosphonate,Analogues of N‐Acetyl‐α‐d‐Glucosamine 1‐Phosphate

Synthesis of α‐C‐ethylene phosphate and phosphonate as well as α‐C‐methylene phosphate analogues of N‐acetyl‐α‐d‐glucosamine 1‐phosphate is reported starting from the common perbenzylated 2‐acetamido‐2‐deoxy‐α‐C‐allyl glucoside. Anomerisation of the corresponding amino α‐C‐glucosyl aldehyde to the β‐aldehyde was observed. Thus, both amino α‐ and β‐C‐glucosyl methanol were obtained after reduction.     

Reaction of N‐Nonaflyl and N‐Cyano‐Benzotriazoles with Enamines

N‐Nonaflyl‐benzotriazole 1a reacts with enamines 2 in tetrahydrofurane (THF) at room temperature to afford o‐nonafluorobutansulfonamido‐phenylazo‐enamines 3 in 74–81% yield. Compound 1a reacts with 1‐diethylaminobutadien 2f twice, affording pyridazine derivative 3f in 20% yield. Ringopening of N‐cyano‐benzotriazole 1b with pyrrolidinocyclohexene 2a affords, under cleavage of pyrrolidine 1,2,3,4‐tetrahydro‐dibenzo[4,5:e]imidazo[1,2‐b][1,2,4]triazine 4 in 43% yield.     

MM3 Conformational Analysis and X‐ray Crystal Structure of 2,3,4,5‐Tetra‐O‐Acetyl‐N,N′‐Dimethyl‐D‐Glucaramide as a Conformational Model for the d‐Glucaryl Unit of Poly(Alkylene 2,3,4,5‐Tetra‐O‐Acetyl‐d‐Glucaramides)

This report describes the MM3 conformational analysis and X‐ray crystal structure of tetra‐O‐acetyl‐N,N′‐dimethyl‐d‐glucaramide as a conformational model for the D‐glucaryl monomer unit of poly(alkylene tetra‐O‐acyl‐d‐glucaramides). The driving force for this study was to determine the conformational preferences for the diacid unit as a function of the increasing steric bulk of pendant O‐acyl groups: acetyl, propanoyl, 2‐methylpropanoyl, and 2,2‐dimethylpropanoyl. The model dialkyl d‐glucaramides all displayed a large vicinal proton coupling between the central backbone glucaryl hydrogens, indicating an essentially fixed anti conformational arrangement of these protons. The MM3 molecular mechanics program was then applied to calculate the corresponding low‐energy conformations of the structurally simplest of these molecules, tetra‐O‐acetyl‐N,N′‐dimethyl‐d‐glucaramide (4). Given the large number of dihedral angles to be considered and the apparent rigidity of these molecules around the central carbons of the glucaryl backbone, a number of conformational approximations based upon model compounds were applied regarding the rotameric disposition of the pendant O‐acetyl and terminal N‐methyl groups. The calculated, and dominant, lowest energy conformer has a sickle structure very similar to the global minimum conformation previously calculated for unprotected d‐glucaramide. The x‐ray crystal structure data from 4 indicated an extended conformation in the solid state and gave solid‐state torsion angle information that was comparable to that obtained computationally.