Intramolecular Photochemical Cross‐Coupling Reactions of 3‐Acyl‐2‐haloindoles and 2‐Chloropyrrole‐3‐carbaldehydes with Substituted Benzenes

Highly efficient syntheses of indolo[2,1‐a]isoquinolines, indolo[2,1‐a][2]benzazepines, pyrrolo[2,1‐a]isoquinolines and pyrrolo[1,2‐a]benzazepines in excellent yields have been achieved by the intramolecular photochemical cross‐coupling reactions of 3‐acyl‐2‐halo‐N‐(ω‐arylalkyl)indoles and 2‐chloro‐N‐(ω‐arylalkyl)pyrrole‐3‐carbaldehydes in acetone. A new heterocyclic ring system – pyrrolo[1,2‐d][1,4]benzoxazepine – has also been constructed for the first time in this work by the photocyclization of 2‐chloro‐N‐(2‐phenoxyethyl)pyrrole‐3‐carbaldehyde.     

Gold‐Catalyzed Sequential Amination/Annulation Reactions of 2‐Propynyl‐1,3‐dicarbonyl Compounds

The gold(III)‐catalyzed sequential amination/annulation reaction of 2‐propynyl‐1,3‐dicarbonyl compounds 1 with primary amines 2 produces 1,2,3,5‐substituted pyrroles 4 in moderate to high yields.     

Synthesis and Reactions of Enantiopure Substituted Benzene cis‐Hexahydro‐1,2‐diols

Enantiopure cis‐dihydro‐1,2‐diol metabolites, obtained from toluene dioxygenase‐catalysed cis‐dihydroxylation of six monosubstituted benzene substrates, have been converted to their corresponding cis‐hexahydro‐1,2‐diol derivatives by catalytic hydrogenation via their cis‐tetrahydro‐1,2‐diol intermediates. Optimal reaction conditions for total catalytic hydrogenation of the cis‐dihydro‐1,2‐diols have been established using six heterogeneous catalysts. The relative and absolute configurations of the resulting benzene cis‐hexahydro‐1,2‐diol products have been unequivocally established by X‐ray crystallography and NMR spectroscopy. Methods have been developed to obtain enantiopure cis‐hexahydro‐1,2‐diol diastereoisomers, to desymmetrise a meso‐cis‐hexahydro‐1,2‐diol and to synthesise 2‐substituted cyclohexanols. The potential of these enantiopure cyclohexanols as chiral reagents was briefly evaluated through their application in the synthesis of two enantiomerically enriched phosphine oxides from the corresponding racemic phosphine precursors.     

Synthesis of 3,4‐Disubstituted Quinolin‐2‐(1H)‐ones via Palladium‐Catalyzed Decarboxylative Arylation Reactions

The Pd‐catalyzed decarboxylative cross‐coupling reaction of 4‐substituted quinolin‐2(1H)‐one‐3‐carboxylic acids with (hetero)aryl halides is described. With palladium(II) bromide and triphenylarsine ligand as the catalyst system, a variety of 4‐substituted 3‐(hetero)aryl quinolin‐2(1 H)‐ones and related heterocycles, such as 4‐substituted 3‐arylcoumarins can be prepared in good to excellent yields.     

Tandem Gold(III)‐Catalyzed Amination‐Intramolecular Hydroamination Reactions of 1‐En‐4‐yn‐3‐ols with Sulfonamides: Efficient Approach to Highly Substituted Pyrroles

A simple, convenient and efficient synthetic approach to highly substituted pyrroles has been developed by utilizing a gold(III)‐catalyzed tandem amination‐intramolecular hydroamination reaction. The first examples of gold‐catalyzed, selective amination of 1‐en‐4‐yn‐3‐ols have also been disclosed.     

Rhodium‐Catalysed Alkoxycarbonylative Cyclisation Reactions of 1,6‐Enynes

The rhodium‐catalysed carbonylation of 1,6‐enynes possessing an electron‐deficient alkenyl moiety in an alcohol reagent in the presence of a rhodium complex proceeded stereo‐ and chemoselectively to afford exocyclic α,β‐enoates.     

Multicatalytic Tandem Reactions of 2‐Alkynylbenzaldoximes with Isocyanides

An efficient tandem reaction of 2‐alkynylbenzaldoximes with isocyanides co‐catalyzed by silver triflate and bismuth triflate has been developed, which gives rise to the unexpected N‐(isoquinolin‐1‐yl)formamides in good to excellent yields. The iodo‐ and bromo‐containing products could be obtained as well by variation of the reaction conditions.     

One‐Pot Cascade Reactions using Fructose‐6‐phosphate Aldolase: Efficient Synthesis of D‐Arabinose 5‐Phosphate,D‐Fructose 6‐Phosphate and Analogues

One‐pot multienzymatic reactions have been performed for the synthesis of 1‐deoxy‐D ‐fructose 6‐phosphate, 1,2‐dideoxy‐D ‐arabino‐hept‐3‐ulose 7‐phosphate, D ‐fructose 6‐phosphate and D ‐arabinose 5‐phosphate. The whole synthetic strategy is based on an aldol addition reaction catalysed by fructose‐6‐phosphate aldolase (FSA) as a key step of a three or four enzymes‐catalysed cascade reaction. The four known donors for FSA – dihydroxyacetone (DHA), hydroxyacetone (HA), 1‐hydroxy‐2‐butanone (HB) and glycolaldehyde (GA) – were used with D ‐glyceraldehyde 3‐phosphate as acceptor substrate. The target phosphorylated sugars were obtained in good to excellent yields and high purity.     

Iodine‐Promoted Domino Reactions of 1‐Cyanocyclopropane 1‐Esters: A Straightforward Approach to Fully Substituted 2‐Aminofurans

A straightforward and efficient iodine‐promoted ring‐opening/cyclization domino reaction of 1‐cyanocyclopropane 1‐esters for the synthesis of fully substituted 2‐aminofurans is reported. This reaction involves the sequential ring‐opening/intramolecular cyclization reaction of 1‐cyanocyclopropane 1‐esters to give the corresponding 2‐amino‐4,5‐dihydrofurans, which were oxidized with I₂ and Et₃N in refluxing toluene to give the corresponding 2‐amino‐3‐furancarboxylates.

     

Efficient Method for the Synthesis of Optically Active 2‐Amino‐2‐chromene Derivatives via One‐Pot Tandem Reactions

The asymmetric synthesis of functionalized 2‐amino‐2‐chromene derivatives with high enantioselectivities via one‐pot tandem reactions of functionalized α,β‐unsaturated ketones with malononitrile catalyzed by 9‐amino‐9‐deoxyepiquinine ( 1a ) in combination with (R)‐1,1′‐binaphth‐2,2′‐diyl hydrogen phosphate ( 1c ) is reported for the first time.     

Synthesis of 2,4‐ and 2,5‐Disubstituted Oxazoles via Metal‐ Catalyzed Cross‐Coupling Reactions

The rapid synthesis of 2,4‐ and 2,5‐disubstituted oxazoles via metal‐catalyzed cross‐coupling reactions is reported. The 4‐ or 5‐position of the corresponding 4‐ or 5‐halogenated 2‐butylthiooxazoles was successfully functionalized via Suzuki–Miyaura, Sonogashira and Stille cross‐coupling reactions. The 2‐position of the 2‐butylthiooxazoles obtained was further coupled to various organozinc reagents through palladium‐ or nickel‐mediated cross‐coupling reactions.     

Diversity‐Oriented Synthesis of Functionalized 1‐Aminopyrroles by Regioselective Zinc Chloride‐Catalyzed,One‐Pot ‘Conjugate Addition/Cyclization’ Reactions of 1,3‐Bis(silyl enol ethers) with 1,2‐Diaza‐1,3‐butadienes

In a convenient one‐pot process, the easily accessible 1,2‐diaza‐1,3‐butadienes and 1,3‐bis(silyl enol ethers) are converted into the previously unknown functionalized 1‐aminopyrroles and 1‐amino‐4,5,6,7‐tetrahydroindoles. The domino reaction proceeds through a zinc chloride‐catalyzed ‘conjugate addition/cyclization’ sequence.     

Three‐Component Reactions of 2‐Alkynylbenzaldoximes and α,β‐Unsaturated Carbonyl Compounds with Bromine or Iodine Monochloride

The three‐component reaction of 2‐alkynylbenzaldoximes and α,β‐unsaturated carbonyl compounds with bromine or iodine monochloride is described, which generates the unexpected 2‐(4‐haloisoquinolin‐1‐yl)ethanol derivatives in good to excellent yields.     

Organocatalytic Asymmetric Mannich Reactions of 5H‐Oxazol‐4‐ones: Highly Enantio‐ and Diastereoselective Synthesis of Chiral α‐Alkylisoserine Derivatives

The first organocatalytic Mannich reaction of 5H‐oxazol‐4‐ones with various readily prepared aryl‐ and alkylsulfonimides has been developed. Two commercially available pseudoenantiomeric Cinchona alkaloids‐derived tertiary amine/ureas have been demonstrated as the most efficient catalysts to access the opposite enantiomers of the Mannich products with equally excellent enantio‐ and diastereoselectivities. From the Mannich adducts, important α‐methyl‐α‐hydroxy‐β‐amino acid derivatives, such as the α‐methylated C‐13 side chain of taxol and taxotere, can be conveniently prepared.     

Polymerization of 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione with diisocyanates

4‐(4′‐Aminophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( 1 ) was reacted with 1,8‐naphthalic anhydride ( 2 ) in a mixture of acetic acid and pyridine (3 : 2) under refluxing temperature and gave 4‐(4′‐N‐1,8‐naphthalimidophenyl)‐1,2,4‐triazolidine‐3,5‐dione ( NIPTD ) ( 3 ) in high yield and purity. The compound NIPTD was reacted with excess n‐propylisocyanate in N,N‐dimethylacetamide solution and gave 1‐(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐triazolidine‐3,5‐dione ( 4 ) and 1,2‐bis(n‐propylamidocarbonyl)‐4‐[4′‐(1,8‐naphthalimidophenyl)]‐1,2,4‐ triazolidine‐3,5‐dione ( 5 ) as model compounds. Solution polycondensation reactions of monomer 3 with hexamethylene diisocyanate ( HMDI ), isophorone diisocyanate ( IPDI ), and tolylene‐2,4‐diisocyanate ( TDI ) were performed under microwave irradiation and conventional solution polymerization techniques in different solvents and in the presence of different catalysts, which led to the formation of novel aliphatic‐aromatic polyureas. The polycondensation proceeded rapidly, compared with conventional solution polycondensation, and was almost completed within 8 min. These novel polyureas have inherent viscosities in a range of 0.06–0.20 dL g^?1 in conc. H₂SO₄ or DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2861–2869, 2003     

1‐Amino‐1‐hydrazo‐2,2‐dinitroethene – a Hazard Warning

1‐Amino‐1‐hydrazo‐2,2‐dinitroethene ( 2 ) has been observed to spontaneously decompose with considerable violence during storage. Its preparation and handling should be regarded as potentially hazardous.     

Synthesis of novel azo‐containing polyureas derived from 4‐[4′‐(2‐hydroxy‐1‐naphthylazo)phenyl]‐1,2,4‐triazolidine‐3,5‐dione

4‐[4′‐(2‐Hydroxy‐1‐naphthylazo)phenyl]‐1,2,4‐triazolidine‐3,5‐dione ( HNAPTD ) ( 1 ) has been reacted with excess amount of n‐propylisocyanate in DMF (N,N‐dimethylformamide) solution at room temperature. The reaction proceeded with high yield, and involved reaction of both N? H of the urazole group. The resulting bis‐urea derivative 2 was characterized by IR, ¹H‐NMR, elemental analysis, UV‐Vis spectra, and it was finally used as a model compound for the polymerization reaction. Solution polycondensation reactions of monomer 1 with Hexamethylene diisocyanate ( HMDI ) and isophorone diisocyanate ( IPDI ) were performed in DMF in the presence of pyridine as a catalyst and lead to the formation of novel aliphatic azo‐containing polyurea dyes, which are soluble in polar solvents. The polymerization reaction with tolylene‐2,4‐diisocyanate ( TDI ) gave novel aromatic polyurea dye, which is insoluble in most organic solvents. These novel polyureas have inherent viscosities in a range of 0.15–0.22 g dL^?1 in DMF at 25°C. Some structural characterization and physical properties of these novel polymers are reported. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3177–3183, 2001     

An Ab Initio Theoretical Study of 2,4,6‐Trinitro‐1,3,5‐Triazine, 3,6‐Dinitro‐1,2,4,5‐Tetrazine,and 2,5,8‐Trinitro‐Tri‐s‐Triazine

In order to evaluate 2,4,6‐trinitro‐1,3,5‐triazine (TNTAz), 3,6‐dinitro‐1,2,4,5‐tetrazine (DNTAz), and 2,5,8‐trinitro‐tri‐s‐triazine (TNTsTAz), the geometries of these compounds have been fully optimized employing the B3LYP density functional method and the AUG‐cc‐pVDZ basis set. The accurate gas phase enthalpies of formation have been obtained by using the atomization procedure and designing isodesmic reactions in which the parent rings are not destroyed. Based on B3LYP/AUG‐cc‐pVDZ calculated geometries and natural charges, the crystal structures have been predicted using the Karfunkel–Gdanitz method. Computed results show that there exists extended conjugation over the parent rings of these compounds. More energy content is reserved in DNTAz than in both TNTAz and TNTsTAz. The title compounds are much more sensitive than 1,3,5‐trinitrobenzene. The calculated detonation velocity of DNTAz reaches 9.73–9.88 km s⁻¹, being larger than those of CL‐20 and TNTAz. TNTsTAz has no advantage over the widely used energetic compounds such as RDX and HMX.     

Preparation of 1,3‐Diazido‐2‐Nitro‐2‐Azapropane from Urea

An alternative method to prepare 1,3‐diazido‐2‐nitro‐2‐azapropane (DANP), a promising liquid component for high‐energy condensed systems, is suggested and involves the following stages: (i) nitration of urea, (ii) condensation of the nitration product with formaldehyde, (iii) acylation (chlorination) of 1,3‐dihydroxy‐2‐nitro‐2‐azapropane, (iv) chlorination of 1,3‐diacetoxy‐2‐nitro‐2‐azapropane, and (v) azidation of the dichloro derivative to DANP. This synthesis method is selective and enables isolation of 1,3‐diazido‐2‐nitrazapropane devoid of impurities.     

Characterization of 4,6‐Diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine

4,6‐Diazido‐N‐nitro‐1,3,5‐triazine‐2‐amine (DANT) was prepared with a 35 % yield from cyanuric chloride in a three step process. DANT was characterized by IR and NMR spectroscopy (¹H, ¹³C, ¹⁵N), single‐crystal X‐ray diffraction, and DTA. The crystal density of DANT is 1.849 g cm⁻³. The cyclization of one azido group and one nitrogen atom of the triazine group giving tetrazole was observed for DANT in a dimethyl sulfoxide solution using NMR spectroscopy. An equilibrium exists between the original DANT molecule and its cyclic form at a ratio of 7 : 3. The sensitivity of DANT to impact is between that for PETN and RDX, sensitivity to friction is between that for lead azide and PETN, and sensitivity to electric discharge is about the same as for PETN. DANT′s heat of combustion is 2060 kJ mol⁻¹.