Synthesis and properties of phosphorus containing polyester‐amides derived from 1,4‐bis(3‐aminobenzoyloxy)‐2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉oxaphosphorin‐6‐yl) phenylene

A series of polyester‐amides that contain phosphorus were synthesized by low temperature solution condensation of 1,4‐bis(3‐aminobenzoyloxy)‐2‐(6‐oxido‐6H‐dibenz〈c,e〉〈1,2〉oxaphosphorin‐6‐yl) phenylene (III) with various aromatic acid chlorides in N‐methyl pyrrolidone (NMP). All polyester‐amides are amorphous and readily soluble in many organic solvents such as dimethylacetamide (DMAc), NMP, dimethylsulfoxide, and dimethylformamide at room temperature or on heating. Light yellow and flexible films of these polyester‐amides could be cast from the DMAc solutions. The polymers with an inherent viscosity of 0.26–0.72 dL/g were obtained in quantitative yields. These polyester‐amides have good mechanical properties (G′ of ∼ 10⁹ Pa up to 200°C) and good thermal and flame retardant properties. The glass transition temperatures of these polyester‐amides ranged from 250 to 273°C. The degradation temperatures (T_d 5%) in nitrogen ranged from 466 to 478°C and the char yields at 800°C were 59.6–65.2%. The limiting oxygen indexes of these polyester‐amides ranged from 35 to 43. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 891–899, 1999     

Enantioselective Synthesis of α‐Hydroxy Amides and β‐Amino Alcohols from α‐Keto Amides

Synthesis of enantiomerically enriched α‐hydroxy amides and β‐amino alcohols has been accomplished by enantioselective reduction of α‐keto amides with hydrosilanes. A series of α‐keto amides were reduced in the presence of chiral Cu^II/(S)‐DTBM‐SEGPHOS catalyst to give the corresponding optically active α‐hydroxy amides with excellent enantioselectivities by using (EtO)₃SiH as a reducing agent. Furthermore, a one‐pot complete reduction of both ketone and amide groups of α‐keto amides has been achieved using the same chiral copper catalyst followed by tetra‐n‐butylammonium fluoride (TBAF) catalyst in presence of (EtO)₃SiH to afford the corresponding chiral β‐amino alcohol derivatives.     

A Facile and Simple Synthesis of Novel 2‐(substituted)‐5‐(1‐methyl‐1H‐indazol‐3‐yl)‐Oxazole Derivatives

Novel 2‐(substituted)‐5‐(1‐methyl‐1H‐indazol‐3‐yl)‐oxazoles ( 13 ) were synthesized in moderate yields, from 1‐methyl‐1H‐Indazole 3‐carboxylic acid ( 1 ), by converting it into a variety of amides ( 12 ) and further its heterocyclization. The structures of all the compounds have been elucidated on the basis of IR, ¹H‐NMR, and HRMS.     

Copper‐Promoted Site‐Selective Acyloxylation of Unactivated C(sp3)H Bonds

The site‐selective acyloxylation of aliphatic amides was achieved via a copper‐promoted C(sp³)? H bond functionalization process directed by a bidentate ligand. The reaction showed a great preference for activating C? H bonds of β‐methyl groups over those of γ‐methyl and unactivated methylene groups.     

Darstellung von Organylquecksilber(II)‐di(methansulfonyl)amiden und Kristallstruktur von Ph–Hg–N(SO2Me)2

Polysulfonylamines. CXXIV. Preparation of Organylmercury(II) Di(methanesulfonyl)amides and Crystal Structure of Ph–Hg–N(SO₂Me)₂ Four N,N‐disulfonylated organylmercury(II) amides R–Hg–N(SO₂Me)₂, where R is Me, ⁱPr, Me₃SiCH₂ or Ph, were obtained on treating the appropriate chlorides RHgCl with AgN(SO₂Me)₂, and characterized by ¹H and ¹³C NMR spectra. In the crystal structure of the phenyl compound (orthorhombic, space group Pbca, Z = 8, X‐ray diffraction at –95 °C), the molecule exhibits a covalent and significantly bent C–Hg–N grouping [bond angle 172.7(3)°; Hg–C 204.0(8), Hg–N 209.1(7) pm]. One sulfonyl oxygen atom forms a short intramolecular Hg…O contact [296.1(5) pm] and simultaneously catenates glide‐plane related molecules via a second Hg…O interaction 297.6(5) pm], thus conferring upon Hg^II the effective coordination number 4 and a geometrically irregular coordination polyhedron (bond angles from 173 to 54°).     

Grenzen für die Bildung lamellarer Metall‐di(arensulfonyl)amide: Drei Lithium‐Komplexe und ein Cadmium‐Komplex

Structures of Ionic Di(arenesulfonyl)amides. 6. Limits to the Formation of Lamellar Metal Di(arenesulfonyl)amides: Three Lithium Complexes and One Cadmium Complex According to low‐temperature X‐ray studies, the new compounds LiN(SO₂C₆H₄‐4‐X)₂ · 2 H₂O, where X = COOH ( 1 ) or COOMe ( 2 ), LiN(SO₂C₆H₄‐4‐CONH₂)₂ · 4 H₂O ( 3 ), and Cd[N(SO₂C₆H₄‐4‐COOH)₂]₂ · 8 H₂O ( 4 ) crystallize in the triclinic space group P1 ( 1 – 3 : Z′ = 1; 4 : Z′ = 1/2, Cd²⁺ on an inversion centre) and display almost perfectly folded anions approximating to mirror symmetry. The lithium ions in 1 – 3 have distorted tetrahedral environments respectively set up by two O=S groups drawn from different anions and two water molecules, two O=S groups of a chelating anion and two water molecules, or one O=C group and three water ligands, whereas the cation of 4 is fully hydrated to form an octahedral [Cd(H₂O)₆]²⁺ complex. The structure refinements for 3 and 4 were marred by positional disorder of the non‐coordinating N(SO₂)₂ moieties. Compounds 1 and 4 extend a previously described series of lamellar metal di(arenesulfonyl)amides where the two‐dimensional inorganic component is comprised of cations, N(SO₂)₂ groups and water molecules and the outer regions are formed by the 4‐substituted phenyl rings. Both crystal packings are governed by self‐assembly of parallel layers through exhaustive hydrogen bonding between carboxylic groups, and there is good evidence that the labile inorganic networks, generated via Li–O and hydrogen bonds in 1 or solely hydrogen bonds in 4 , are efficiently stabilized by the strong cyclic (COOH)₂ motifs within the interlayer regions. In the absence of these, the lamellar architecture is seen to collapse in 2 and 3 , where the carboxyl groups are replaced by methoxycarbonyl or carbamoyl functions and the inorganic components are segregated in parallel tunnels pervading the anion lattices.     

Utilizing Carbonyl Coordination of Native Amides for Palladium‐Catalyzed C(sp3)−H Olefination

Pd^II‐catalyzed C(sp³)?H olefination of weakly coordinating native amides is reported. Three major drawbacks of previous C(sp³)?H olefination protocols, 1) in situ cyclization of products, 2) incompatibility with α‐H‐containing substrates, and 3) installation of exogenous directing groups, are addressed by harnessing the carbonyl coordination ability of amides to direct C(sp³)?H activation. The method enables direct C(sp³)?H functionalization of a wide range of native amide substrates, including secondary, tertiary, and cyclic amides, for the first time. The utility of this process is demonstrated by diverse transformations of the olefination products.     

Synthesis of Nitrogen‐Containing Derivatives of (18α,19β)‐19‐Hydroxy‐2,3‐secooleanane‐2,3,28‐trioic Acid 28,19‐Lactone

The object of this study is the interaction of the cyclic anhydride 2 of (18α,19β)‐19‐hydroxy‐2,3‐secooleanane‐2,3,28‐trioic acid 28,19‐lactone ( 1 ) with primary and secondary amines. It was shown that the products of steric control (the corresponding 2‐amino‐2‐oxo‐3‐oic acids=2‐amides) were formed solely upon the opening of the anhydride cycle by secondary amines (Scheme 2), whereas the interaction with primary amines yielded a mixture of isomeric amides (Scheme 10). In the latter case, the solvent provided a noticeable effect on the reaction selectivity, which was demonstrated in the case of 4‐methoxybenzylamine. The interaction between the resulting 3‐amides and oxalyl chloride yielded the corresponding cyclic imides, whereas under these conditions, 2‐amides formed spiropyrrolidinetriones (Scheme 4).     

Onium‐di(arensulfonyl)amide: Von der gestreckten zur gefalteten Konformation des (ArSO2)2N⊖‐Anions

Structures of Ionic Di(arenesulfonyl)amides. 1. Onium Di(arenesulfonyl)amides: From the Extended to the Folded Conformation of the (ArSO₂)₂N^⊖ Anion In a study preceding the investigation of lamellar metal di(arenesulfonyl)amides, the bonding and conformational characteristics of non‐coordinating (ArSO₂)₂N^⊖ ions have been established within a series of appropriate onium salts. Starting from the strong NH acids HN(Q‐4‐X)₂, where Q = SO₂C₆H₄, the following model compounds were prepared by neutralization or cocrystallization procedures and subjected to low‐temperature X‐ray analyses: Pr₄N^⊕. ^⊖N(Q‐4‐COOMe)₂ ( 2 , monoclinic, space group C2/c, Z = 4), Pr₄N^⊕ · ^⊖N(Q‐4‐COOH)₂ ( 3 , monoclinic, Cc, Z = 4, O₂SNSO₂ group disordered), Me₃NOH^⊕ · ^⊖N(Q‐4‐F)₂ ( 4 , monoclinic, P2₁/n, Z = 4), [DA18C6]^2⊕ · 2 ^⊖N(Q‐4‐H)₂ ( 6 , cation = 1,10‐diazonia‐18‐crown‐6, monoclinic, P2₁/c, Z = 2), [DA18C6]^2⊕ · 2 ^⊖N(Q‐4‐Me)₂ ( 7 , triclinic, P1, Z = 1), and [DA18C6]^2⊕ · 2 ^⊖N(Q‐4‐Cl)₂ · 2 CH₂Cl₂ ( 8 , monoclinic, P2₁/c, Z = 2). Structures 2 – 4 represent the energetically favoured, extended or open conformation of the CO₂S–N–SO₂C bridge (crystallographic twofold symmetry for 2 , pseudo‐C₂ symmetry for 3 and 4 ), whereas in 6 – 8 the anions adopt the folded or hair‐pin conformation (pseudo‐C_s symmetry), which is a prerequisite in lamellar structures. The interdependence of bond lengths and angles within ^⊖N(SO₂C)₂ and HN(SO₂C)₂ moieties is substantiated. In 6 – 8 , the [DA18C6]^2⊕ macrocycles exhibit the well‐known “biangular” C_i conformation and are connected to two symmetry related anions by N–H…O hydrogen bonds; structures 4 and 3 respectively display O–H…N bonded cation‐anion pairs or C(O)–O–H…O=S mediated anion chains. Weak hydrogen bonds C–H…O are observed in all the crystal packings. The hitherto unreported amines HN(Q‐4‐X)₂, where X is C(O)OMe or C(O)NH₂, were obtained by treating the corresponding dicarboxylic acid with OSCl₂ to form the bis(acyl chloride) and subjecting the latter to methanolysis or ammonolysis.     

Stereoselective Synthesis of α‐ and β‐Glycofuranosyl Amides by Traceless Ligation of Glycofuranosyl Azides

A highly stereoselective synthesis of α‐ or β‐glycofuranosyl amides based on the traceless Staudinger ligation of glycofuranosyl azides of the galacto, ribo, and arabino series with 2‐diphenylphosphanyl‐phenyl esters has been developed. Both α‐ and β‐isomers can be obtained with excellent selectivity from a common, easily available precursor. The process does not depend on the anomeric configuration of the starting azide but appears to be controlled by the C2 configuration and by the protection/deprotection state of the substrates. A mechanistic interpretation of the results, supported by ³¹P NMR experiments, is offered and merged with our previous mechanistic analysis of pyranosyl azide ligation reactions.     

Derivatives of 5‐Oxy‐pyrido[2,3‐b]quinoxaline‐9‐carboxylic acid: A tricyclic system useful for the synthesis of potential intercalators

The synthesis of a new series of 5‐oxy‐pyrido[2,3‐b]quinoxaline‐9‐carboxamides 4a‐i and N¹,N²‐Bis(5‐oxy‐pyrido[2,3‐b]quinoxaline‐9‐benzoyl)ethylenediamine ( 5 ) is reported starting from 2‐chloro‐3‐nitropyri‐dine. Fundamental steps of the synthetic pathway are i) preparation of 2‐(3‐nitro‐pyridin‐2‐ylamino)benzoic acid ( 1 ) via copper‐catalyzed condensation of 2‐chloro‐3‐nitropyridine with o‐anthranilic acid, ii) intramolecular cyclization of the acid 1 to 5‐oxy‐pyrido[2,3‐b]quinoxaline‐9‐carboxylic acid ( 2b ) upon treatment with concentrated sulfuric acid and oleum and iii) conversion of the acid 2 to the desired amides 4a‐i and 5 . Compounds 4a‐i and 5 are oxygenated azaanalogs of phenazines, a wellknown series of intercalators with cytotoxic activity.     

Photochemistry of N‐(2‐Acylphenyl)‐2‐methylprop‐2‐enamides: Competition between Photocyclization and Long‐Range Hydrogen Abstraction

The photochemical reactions of various ‘N‐methacryloyl acylanilides’ (=N‐(acylphenyl)‐2‐methylprop‐2‐enamides) have been investigated. Under irradiation, the acyl‐substituted anilides 1a – 1c and 1o afforded exclusively the corresponding quinoline‐based cyclization products of type 2 (Table 1). In contrast, irradiation of the benzoyl (Bz)‐substituted anilides 1e – 1h afforded a mixture of the open‐chain amides 4e – 4h and the cyclization products 2e – 2h . Irradiation of the para‐acyl‐substituted anilides 6a – 6e and 6h afforded the corresponding quinoline‐based cyclization products of type 5 as the sole products (Table 2). The formation of the cyclization products 2a – 2c and 2o can be rationalized in terms of 6π‐electron cyclization, followed by thermal [1,5] acyl migration, and that of compounds 3p, 5a – 5e , and 5h can be explained by a 6π‐electron cyclization only. The formation of the open‐chain amides 4e – 4h probably follows a mechanism involving a 1,7‐diradical, C and a spirolactam of type D (Scheme). Long‐range ζ‐H abstraction by the excited carbonyl O‐atom of the benzoyl group on the aniline ring is expected to proceed via a nine‐membered cyclic transition state, as proposed on the basis of X‐ray crystallographic analyses (Fig. 2).     

Synthesis and characterization of novel chelated dimethylamino lithium arylamide dimers: molecular structure of [1‐LiNPhCHPhCH2‐2‐NMe2C6H4]2

The reaction of 1‐NHPhCHPh‐2‐NMe₂C₆H₄ ( 1 ) and 1‐NHPhCHPhCH₂‐2‐NMe₂C₆H₄ ( 2 ) with n‐BuLi in diethyl ether gave the solvent‐free chelated dimethylamino lithium amides [1‐LiNPhCHPh‐2‐NMe₂C₆H₄]₂ ( 3 ) and [1‐LiNPhCHPhCH₂‐2‐NMe₂C₆H₄]₂ ( 4 ). The lithium amides 3 and 4 were characterized by ¹H, ⁷Li, and ¹³C NMR spectroscopy. A crystal structure determination was carried out on 4 , which is the first example of a structurally characterized solvent‐free dimeric chelated dimethylamino lithium arylamide with three‐coordinate lithium centers that contains a seven‐membered chelate ring. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis of 4‐fluoroalkyl‐2H‐pyrido [1, 2‐a] pyrimidin‐2‐ones from 2, 2‐dihydropolyfluoroalkanoic acids

In the presence of N, N′‐dicyclohexylcarbodiimide, 2‐aminopyridine and its derivatives (2) condensed with 2, 2‐di‐hydropolyfluoroalkanoic adds (1) to give the corresponding amides. Subsequent intramolecular Micheal addition‐elimination reactions of the fluorine‐containing amides under basic conditions gave 4‐fluoroalkyl‐2H‐pyrido[1,2‐a]pyrimidin‐2‐ones (3) in good yields.     

Experimental versus theoretical evidence for the rate‐limiting steps in uncatalyzed and H+‐ and HO−‐catalyzed hydrolysis of the amide bond

Recent theoretical studies of the alkaline hydrolysis of the amide bond have indicated that the nucleophilic attack of the hydroxide ion at the carbonyl carbon of the amide group is rate limiting. This is shown to be inconsistent with a large amount of experimental observations where the expulsion of the leaving group has been shown to be rate limiting. A kinetic approach has been described, which allows us to diagnose whether the pH‐independent/uncatalyzed hydrolysis of amides involves (a) both the uncatalyzed water reaction (k_w) and H⁺‐ (k_H) and HO^?‐catalyzed (k_OH) water reaction, (b) only the k_w reaction, or (c) only the k + k_OH reaction. The analysis described in this critical review does not favor the recent theoretical claims of the absence of the water reaction in the pH‐independent/uncatalyzed hydrolysis of formamide and urea. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 599–611, 2009     

Cyclic Hydroboration – The Structure of Perhydro‐9b‐boraphenalenes

Complete hydroboration of cyclododecatrienes was reported to give two isomers, depending on conditions. The assignment of their structure had been attempted without unequivocal proofs. We have now used NMR spectroscopy (¹¹B, ¹³C, ¹⁵N and ²³Na NMR) to study the sodium amides of these two polycyclic boranes. In addition, one of the isomeric borates could be crystallized, and the X‐ray analysis revealed a cis‐,cis‐,trans configuration of the six‐membered rings reversing the original structural assignment.     

Octanuclear Cu(I)‐dithiophosphates: An Efficient Catalyst System for N‐Arylation of Azoles,Amines, and Amides

The formation of a C‐N bond via the cross‐couplings of aryl iodides with azoles, aryl amine, and amides can be successfully achieved in decent yield by the utilization of both [Cu ₈(H){S₂P(OⁱPr)₂}₆]⁺ and [Cu₈{S₂P(OEt)₂}₆]²⁺ as the pre‐catalysts.     

The synthesis of n‐substituted isothiazol‐3(2h)‐ones from nsubstituted 3‐benzoylpropionamides

N‐Substituted isothiazol‐3(2H)‐ones can be easily prepared from N‐substituted 3‐benzoylpropi‐onamides in two experimentally simple steps, in satisfactory overall yields. Reaction of the amides with excess thionyl chloride results in the formation of N‐substituted 5‐benzoylisothiazol‐3(2H)‐ones, which are readily debenzoylated with alkali to the corresponding N‐substituted isothiazol‐3(2H)‐ones. This method has now been successfully applied to the synthesis of isothiazolones N‐substituted with a bulky alkyl group, such as the tert‐butyl group, and with a phenyl group bearing either a strong electron‐withdrawing substituent, such as the 3‐nitrophenyl and 4‐nitrophenyl group, or an electron‐releasing substituent, such as the 4‐methylphenyl and 4‐methoxyphenyl group.     

Enamides via Long‐Distance Migration of Double Bonds

A new method for preparation of enamides (N‐(alken‐1‐yl) amides) by means of the ‘long‐distance' migration of the double bond in unsaturated amides in the presence of [Fe(CO)₅] is described. The method is shown to be particularly useful for the isomerization of N‐(but‐3‐enyl)amides, while, in the case of N‐(pent‐4‐enyl) and N‐(hex‐5‐enyl) amides the mixture of products was formed and the yield of the enamide was relatively low.     

CH-Acidität in α-Stellung zum N-Atom in N,N-dialkylamiden mit sterisch geschützter Carbonylgruppe zur nucleophilen minoalkylierung

CH-Acidity in α-position to the N-Atom of N, N -Dialkylamides with Sterically Protected Carbonyl Groups Contribution to the Nucleophilic Amino Alkylation Sterically protected amides 1 such as the 2,4,6-triisopropyl-benzoic acid derivatives 3, 8b and 10 undergo readily H/Li-exchange with s-butyllithium at the CH₃N- or CH₂N-groups. The resulting organolithium compounds (cf. 9, 11 ) are alkylated and hydroxyalkylated with primary haloalkanes, aldehydes, and ketones under chain elongation in the amine position of the amides. The (E/Z)-rotamers of the dialkylamides 7 and 8 are separated by chromatography; the amides 4 – 6 , 12 , and 13 formally derived from β-hydroxyamines are obtained in the (Z)-form only. The configurational (E/Z)-assignments follow from NMR. and IR. data. The erythro and threo configuration of the two diastereomeric amides 12a and 12b are tentatively concluded from Eu(fod)₃-¹H-NMR.-shift experiments. The results strongly suggest that the H/Li-exchange takes place regioselectively at the CH? N group which is in cis-position to the C?O double bond (→ 14 ). The methyl 2,4,6-tri(t-butyl)benzoate ( 18 ) can also be deprotonated to the lithium acyloxymethanide 19 which is trapped by alkylation with 1-iodooctane (→ 20 ). – The steric protection of the carbonyl groups in the products 4 – 8, 10, 12, 13 , and 20 prevents their ready hydrolysis to amines and alcohols, respectively. Therefore, triphenylacetic acid derivatives 21 rather than 2,4,6-triisopropylbenzoic acid derivatives for use in the electrophilic substitution of equation (1) are recommended. The trityl group in 21 may be considered a C-leaving-group (C? C protective group, cf. 22, 23 ). The acetamide 25 reacts readily (→ 26 ) and then with electrophiles to give products 27a – c . As shown in the Table, the amides 27 are cleaved under a variety of conditions with formation of triphenylmethane. LiAlH₄ produces a tertiary amine, CH₃Li a secondary amine, and dissolving alkali metals/naphthalene under aprotic conditions mixtures of secondary amine and its formamide (hydrolysed by acid treatment). Thus the overall process (2) is feasible.