Preparation of α,ω-ditriazinylperfluoroalkane derivatives

The synthesis of 2-oxa and 2-thiaperfluoroglutaric acids and their corresponding ethyl esters, amides, nitriles, acid chlorides, and also 2-thiaperfluoroglutaric anhydride are described. These compounds were prepared as precursors to α,ω-ditriazinylperfluoroalkane derivatives containing a heteroatom in the perfluoroalkylene chain. The ditrazinylpropanes were prepared most satisfactorily from the diacid chlorides rather than the dinitriles.     

α,ω-Diisocyanatocarbodiimides, -Polycarbodiimides,and Their Derivatives

Research in the field of low-molecular weight, oligomeric and polymeric α,ω-diisocyanatocarbodiimides and -polycarbodiimides has been fruitful, not only in connection with these compounds themselves, but also—as so often happens in chemistry—with quite different problems. Novel synthetic methods, discoveries concerning the properties of low-molecular weight carbodiimides and phosphane imide derivatives, as well as results on the fragmentation reactions of four-membered heterocyclic compounds containing oxygen, phosphorus, and nitrogen, and a better understanding of the diisocyanate polyaddition process are among the many by-products of this research. The “high- and low-temperature formation” of polycarbodiimides and the homogeneous and heterogeneous catalysis of this process are described, and the fundamental importance of four-membered ring fragmentation mechanisms resulting in the formation of phosphane imide derivatives is outlined. Interesting building blocks for the diisocyanate polyaddition and polycondensation processes can be synthesized by many derivatization reactions of oligomeric and high-molecular weight polycarbodiimides and polyuretonimines. The in situ production of polycarbodiimides via matrix reactions in flexible polyurethane foams leads to a cellular arrangement of the material due to the pronounced symmetrical growth processes. Combination-foams with increased carbonation tendencies are formed in this way. Attention is drawn to several industrial applications of α,ω-diisocyanatopolycarbodiimides, of high-molecular weight cross-linked polyuretonimines, and of polycarbodiimide foams.     

Synthesis of Pyrido[2′,3′: 3,4]pyrazolo[1,5‐a]pyrimidine,Pyrido[2′,3′:3,4]pyrazolo[5,1‐c][1,2,4]triazine,and Pyrazolyl Oxadiazolylthieno[2,3‐b]pyridine Derivatives

6‐(2‐Thienyl)‐4‐(trifluoromethyl)‐1H‐pyrazolo[3,4‐b]pyridine‐3‐amine reacted with different active methylene compounds to afford pyridopyrazolopyrimidine derivatives. On the other hand, it reacted with some halo compounds to give the imidazo[1′,2′:1,5]pyrazolo[3,4‐b]pyridine derivatives. Also, it diazotized to give the corresponding diazonium chloride that is coupled with several active methylene compounds to give the corresponding triazine derivatives. Furthermore, compound 3‐amino‐6‐(2(thienyl)‐4‐(trifluoromethyl)thieno[2,3‐b]pyridine‐2‐carbohydrazide reacted with some β‐dicarbonyl compounds and some sulfur‐containing compounds to afford the corresponding pyrazolyl oxadiazolylthieno[2,3‐b]pyridine derivatives.     

α,ω-Dihydroxyalkan-α,α-diphosphonsäuren durch Desaminierung von ω-Aminoalkandiphosphonsäuren

α,ω-Dihydroxyalkane-α,α-diphosphonic Acids by Desamination of ω-Aminoalkanediphosphonic Acids The title compounds represent a new group of complexing diphosphonic acids which are synthesized by desamination of ω-amino-α-hydroxyalkane-α,α-diphosphonic acids. In case of α,ω-dihydroxypropane-α,α-diphosphonic acid ( 1 ) a phosphonylated phostone is formed by dehydration. In contrast, the ω-phenyl drivative of ( 1 ) yields in a smooth reaction under the same conditions 2-hydroxy-5-phenyl-3-phosphono-1.2-oxaphosphol-3-en-2-oxide ( 6 ).     

Some reactions with ω-bromoacetophenone: Synthesis of Δαβ-butenolide and its transformation into pyrrole derivatives

ω-Bromoacetophenone reacts with the sodium salt of ethyl cyanoacetate to afford α-cyano-β-phenyl-Δ^αβ-butenolide. This butenolide undergoes azo coupling with diazotized aromatic amines (ArNH₂) to afford the hydrazo derivatives. These hydrazo derivatives (ArPh, 4-ClC₆H₄, 4-MeC₆H₄, 4-MeOC₆H₄) were transformed into the corresponding 3(2H)-pyridazinone derivatives on stirring in methanol in the presence of potassium hydroxide. These latter compounds were converted into the corresponding 3-cyano-2,5-dihydroxy-4-phenyl-N-arylpyrrole derivatives on reduction with zinc dust in refluxing acetic acid, presumably via reductive cleavage of the N N bond of the pyridazine followed by recyclization via loss of ammonia.     

Synthesen von ω-substituierten ω-Nitrocarbonsäureestern aus α-Nitrocycloalkanonen

Synthesis of ω-Nitroalkanoates Substituted in ω-Position from α-Nitrocycloalkanones α-Nitrocycloalkanones substituted in α-position by a functionalized alkyl residue underwent ring opening to the corresponding chain derivatives by intermolecular nucleophilic attack; ω-nitroalkanoates substituted in ω-position were obtained (Scheme 1). The so formed methyl 6-nitro-9-oxodecanoate ( 3 ) was used to prepare methyl 8-(2-methyl-1,3-dioxolan-2-yl)octanoate ( 15 ), an intermediate in the synthesis of the sex phermone of the honey bee.     

Reaction of ω-cyanoacetophenone and some of its derivatives with secondary amines. New synthesis of aminopyridine derivatives

ω-Cyanoacetophenone (1a) and its derivatives 1b-c react with morpholine (or piperidine) to give mainly 2,4-diaryl-3-eyano-6-morpholino- (or piperidino-) pyridine derivatives (5) ; relative β-aminoeinnamonitriles 6 and very small amounts of amidines 4 are also obtained. When pyrrolidine is used compounds 5 cannot be detected and enamines 6 are the main product. A mechanism involving the intermediate formation of enamines 6 (as electrophiles) and of carbanions 11 (as nucleophiles) is proposed to explain this new synthesis of aminopyridine derivatives.     

Synthèse et caractérisation d'une série de bis-9,9′(thio-9-acridinyl)-α,ω-alcanes

Some new bis-acridine derivatives have been prepared under phase transfer catalysis conditions. These are α,ω-bis-(9-thioacridinyl)alkanes with or without heteroatoms such as N or O, included into the bridge. In the latter case, general procedure has to be slightly modified due to a side-reaction leading to thiobenzyl derivatives, which increases in the conditions proposed in the first place. The compounds so prepared were characterized by their melting points, ¹H and ¹³C nmr data. Preliminary results referring to activity against P-388 lymphocitic leukemia are presented.     

Stereoselektive reduktive Dimerisierung von α-Cyan-β-(4-pyridyl)acrylsäurederivaten

Stereoselective Reductive Dimerisation of α-Cyano-β-(4-pyridyl)acrylic Acid Derivatives Catalytic hydrogenation of the α-substituted β-(4-pyridyl)acrylonitriles 3 and 4 (see Scheme 3) yields via stereoselective reductive dimerization the substituted cyclo-pentene derivatives 7 and 8 (see Scheme 4 and 5) instead of the expected dihydro-products 5 and 6 . The mechanism of this reaction is discussed. The structure and relative configuration of 10 have been established by X-ray single crystal analysis.     

Darstellung und Charakterisierung von α,ω-Dihydroperchloroligosilanen

Preparation and Characterization of α,ω-Dihydroperchloro Silanes Synthesis for the new compounds H(SiCl₂)_nH, n = 3?7 and HSi₄Cl₅ were described, starting from the perphenylated cyclosilanes. The new compounds were characterized and ¹H- and ²⁹Si-NMR spectra are discussed.     

Ligand coupling of 2-pyridyl sulfoxides having an sp2 stereocenter at the α-position: A novel preparation of α-stilbazoles

Ligand coupling of (E)- and (Z)-styryl 2-pyridyl sulfoxides with methylmagnesium bromide gave (E)-and (Z)-2-styrylpyridine, respectively in a stereospecific manner. A number of (E)-2-styrylpyridine derivatives were prepared by the coupling reaction. Methyl styryl sulfoxide and 2,2′-bipyridyl were obtained as by-products. The mechanism of the reaction is discussed based on quantitative analysis of the products.     

Factors Influencing the Course of the Macrocyclization of α,ω‐Diamines with Esters of α,ω‐Dicarboxylic Acids

The efficient synthesis of eight new macrocyclic amides (lactams) via reaction of diesters with diamines under normal dilution conditions is described. The role of intermolecular H‐bond formation and steric hindrance is discussed based on ¹H‐ and ¹⁵N‐NMR studies of appropriate model compounds. Principles for the optimal choice of esters that can be efficiently transformed into diamides have been developed.     

Addition de dérivés maloniques sur des β-énaminones cycliques

The addition of activated acctonitriles 6 on cyclic and benzylic β-enaminoketones 5 under basic conditions (sodium ethoxide or trition B) have been investigated. This reaction leads exclusively to the formation of α-pyrones 8 and never to the pyridine ring. The strucutre of the newly synthesized α-pyrone derivatives 8 are supported by nmr and ir spectral data.     

Base-catalyzed redox reactions of α-hydroxyalkylazaaromatic N-oxides

The (α-hydroxybenzyl)pyridine 1-oxides on heating with aqueous sodium hydroxide yielded the corresponding benzoylpyridines in redox reactions. When the phenyl groups of the foregoing compounds was replaced by hydrogen or methyl the redox reactions occurred less readily. A kinetic isotope effect of 3 was found for 4-(α-deuterio-α-hydroxybenzyl)pyridine 1-oxide on reaction with sodium hydroxide. The removal of the α-deuterio group is non-reversible. A mechanism consistent with these observations is given. 6-Acetoxyphenanthridine 5-oxide yielded with concentrated hydrochloric acid a redox product, 6-formylphenanthridine hydrochloride, whereas under the same conditions neither (α-hydroxybenzyl)pyridine 1-oxides nor 2-hydroxy-methylquinoline 1-oxide yielded a redox product.     

Cyclization reactions of ω-tosyloxy-1-alkynyl- and ω-tosyloxy-1-alkenylborates and their ω-halo analogues

The reaction of trialkylboranes with ω-tosyloxy-1-lithio-1-alkynes can induce transfer of an alkyl group from the boron atom to the alkynyl carbon atom with concomitant formation of four- through six-membered carbocycles via intramolecular displacement of the ω-tosyloxy group. The stereoselectivity of the reaction, however, is low (anti/syn≃1.6–1.7). The corresponding reaction of ω-halo- or ω-tosyloxy-1-alkenylborates also gives exocyclic alkenes via 1,2-migration-cyclization followed by dehydroboration. In the cases of cyclopropanation, cyclopropylcarbinyl-to-homopropargyl rearrangement rather than dehydroboration takes place. Diphenylzirconocene reacts similarly with 6-lithio-5-hexynyl tosylate to give phenylmethylenecyclopentane in 45% yield. On the other hand, attempts to induce a similar migration with phenyl derivatives of Y, V, Cr, and Mn have led to < 5–10% yields of the same cyclization product.     

The synthesis of β-heteroarylamino-α,β-dehydro-α-amino acid and β-heteroarylamino-α-amino acid derivatives

From heteroarylaminomethyleneoxazolones 4 , obtained from N-heteroarylformamidines 2 and 2-phenyl-5-oxo-4,5-dihydro-1,3-oxazole ( 3 ), the following β-heteroarylamino-α,β-dehydro-α-amino acid derivatives were prepared: methyl 8 and ethyl esters 9 , amides 10 and 11 , hydrazides 12 , and azides 15 . By catalytic hydrogenation the compounds 4 were converted into β-heteroarylamino substituted amides 18 and β-heteroarylamino-α-amino acids 20 .     

Catalytic Asymmetric 1,2‐Addition of α‐Isothiocyanato Phosphonates: Synthesis of Chiral β‐Hydroxy‐ or β‐Amino‐Substituted α‐Amino Phosphonic Acid Derivatives

α‐Amino phosphonic acid derivatives are considered to be the most important structural analogues of α‐amino acids and have a very wide range of applications. However, approaches for the catalytic asymmetric synthesis of such useful compounds are very limited. In this work, simple, efficient, and versatile organocatalytic asymmetric 1,2‐addition reactions of α‐isothiocyanato phosphonate were developed. Through these processes, derivatives of β‐hydroxy‐α‐amino phosphonic acid and α,β‐diamino phosphonic acid, as well as highly functionalized phosphonate‐substituted spirooxindole, can be efficiently constructed (up to 99 % yield, d.r. >20:1, and >99 % ee). This novel method provides a new route for the enantioselective functionalization of α‐phosphonic acid derivatives.     

Synthesis of Highly Substituted Pyridines through Copper‐Catalyzed Condensation of Oximes and α,β‐Unsaturated Imines

A copper‐catalyzed condensation reaction of oxime acetates and α,β‐unsaturated ketimines to give pyridine derivatives is reported. The reaction features mild conditions, high functional‐group compatibility, and high regioselectivity with respect to unsymmetrical oxime acetates, thus allowing the preparation of a wide range of polysubstituted pyridines, many of which are not readily accessible by conventional condensation methods.     

Tautoméric entre structures α-aleoxy énaminocétone et β-céto iminoéther présentée par les pipéridéines résultant de la semihydrogénation d'alcoxy-2 acyl-3 pyridines

The palladium or platinium-catalyzed partial hydrogenation of some 2-alkoxy-3-acylpyridines has been performed in order to study the tautomerism of the resulting tetrahydropyridines. Reduction of the pyridine ring to tetrahydropyridine occurs selectively for the bicyclic compounds 2 and 3, while predominant reduction of the keto group takes place in the case of the derivative 1 carrying the acyl group in an open chain; this different behaviour towards partial hydrogenation is tentatively explained as a consequence of “I-strain” effect. Whereas the bicyclotetrahydropyridine 6 and 7 present exclusively an α-alkoxy enaminoketone structure, the open chain substituted tetrahydro-pyridine 5 exists only as a β-keto iminoether as shown by ir and proton nmr studies. Total displacement of tautomerism towards one of these two structures is interpreted as the result of the unfavourable interaction of nitrogen and oxygen lone pairs which would occur in a bicyclic iminoether, as compared to the stabilizing interaction of an oxygen lone pair and the N-H bond of the enaminoketone structure, which can be realized without increase of steric crowding in the bicyclic case.     

Stabilization of High‐Valence Ruthenium with Silicotungstate Ligands: Preparation,Structural Characterization,and Redox Studies of Ruthenium(III)‐Substituted α‐Keggin‐Type Silicotungstates with Pyridine Ligands, [SiW11O39RuIII(Py)]5−

Ruthenium(III)‐substituted α‐Keggin‐type silicotungstates with pyridine‐based ligands, [SiW₁₁O₃₉Ru^III(Py)]^5?, (Py: pyridine ( 1 ), 4‐pyridine‐carboxylic acid ( 2 ), 4,4′‐bipyridine ( 3 ), 4‐pyridine‐acetamide ( 4 ), and 4‐pyridine‐methanol ( 5 )) were prepared by reacting [SiW₁₁O₃₉Ru^III(H₂O)]^5? with the pyridine derivatives in water at 80 °C and then isolated as their hydrated cesium salts. These compounds were characterized using cyclic voltammetry (CV), UV/Vis, IR, and ¹H NMR spectroscopy, elemental analysis, titration, and X‐ray absorption near‐edge structure (XANES) analysis (Ru K‐edge and L₃‐edge). Single‐crystal X‐ray analysis of compounds 2 , 3 , and 4 revealed that Ru^III was incorporated in the α‐Keggin framework and was coordinated by pyridine derivatives through a Ru? N bond. In the solid state, compounds 2 and 3 formed a dimer through π? π interaction of the pyridine moieties, whereas they existed as monomers in solution. CV indicated that the incorporated Ru^III–Py was reversibly oxidized into the Ru^IV–Py derivative and reduced into the Ru^II–Py derivative.