Metathesis reactions of β-acyloxysulfones: synthesis of 1,6- and 1,7-dienes

A novel alkene-masking strategy has been developed that allows for a metathesis approach to 1,6- and 1,7-dienes. This method was successfully applied to the synthesis of a long-chain alkenone natural product.     

Cycloaddition reactions of 1,5-, 1,6- and 4,6-benzo[h]naphthyridinium N-dichloromethylides with dimethyl acetylenedicarboxylate

Summary Cycloaddition reactions of 1,5-, 1,6-, and 4,6-benzo[h]naphthyridinium N-dichloromethylides with dimethyl acetylenedicarboxylate are reported. Ylides were formedin situ from corresponding benzo[h]naphthyridines and dichlorocarbene.

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Cycloadditionsreaktionen von 1,5-, 1,6- und 4,6-Benzo[h]naphthyridinium-N-dichloromethyliden mit Acetylendicarbonsäuredimethylester

Zusammenfassung Es wurden Cycloadditionsreaktionen von 1,5-, 1,6- und 4,6-Benzo[h]naphthyridinium-N-dichloromethyliden mit Acetylendicarbonsäuredimethylester untersucht. Die Ylide werdenin situ aus den entsprechenden Benzo[h]naphthyridinen und Dichlorcarben erhalten.

     

Novel tricyclic diamines 2. Synthesis of 1,7-diazaisoadamantane, 1,5-diazaisoadamantane and 1,6-diazahomobrendane

Three novel tricyclic diamines (1,7-diazaisoadamantane, 1,5-diazaisoadamantane and 1,6-diazahomobrendane) were prepared. A flexible synthetic strategy was employed which used flat, aromatic azaindoles as the starting materials. The requisite azaindoles were prepared by a tandem Sonogashira coupling/intramolecular cyclization reaction. Ring saturation, appropriate functionalization and intramolecular alkylation provided the three novel tricyclic diamines cores.     

Reactions of dialkyl 4-bromo-2,2-dimethyl-3-oxohexane-1,6-dioates,-heptane-1,7-dioates with zinc and aromatic aldehydes

Zinc enolates generated from dimethyl 4-bromo-2,2-dimethyl-3-oxohexane-1,6-dioate and zinc reacted with aromatic aldehydes giving methyl 2,2-dimethyl-3-oxo-3-(5-oxo-2-aryltetrahydrofuran-3-yl)propanoates. The reaction of zinc enolates obtained from dimethyl 4-bromo-2,2-dimethyl-3-oxoheptane-1,7-dioate and zinc with aromatic aldehydes depending on the synthesis conditions led to the formation either methyl 2,2-dimethyl-3-oxo-3-(6-oxo-2-aryltetrahydropyran-3-yl)propanoates or 3-(5,5-dimethyl-4,6-dioxo-2-aryltetrahydropyran-3-yl)propanoates. The compounds synthesized formed as a single diastereomer of E-configuration.     

Spectroscopic and theoretical studies of derivatives of 1,6- and 1,7-naphthyridines

The solvatochromism in 8-hydroxy-1,6-naphthyridin-5(6H)-one-7-carboxylic acid methyl ester (1), 5-hydroxy-1,7-naphthyridin-8(7H)-one-6-carboxylic acid methyl ester (2), and 4-hydroxy-2-methyl-1(2H)-isoquinolone-3-carboxylic acid methyl ester (3), has been studied in solvents of different polarity and hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) ability. The relative stabilities of isomers for these naphthyridine derivatives and their interaction with the solvent are reported. Two intramolecular hydrogen-bonded structures contribute to the ground state of compound 1. Temperature effects on the absorption bands were recorded to analyse the possible equilibrium between covalent and zwitterionic forms. The formation of zwitterionic species was observed only in HBD solvents, from which is inferred the solvent assistance in the proton transference. AM1 and PM3 semi-empirical calculations were used in support of the proposed interpretations.     

Synthesis and Reactivities of 1,5- and 1,7-Azulenequinone Derivatives. A Highly Convenient,One-Pot Synthesis of 3-Bromo-1,5- and −1,7-Azulenequinones by Bromination of Azulene,

A very convenient, one-pot synthesis (over 80% yield) of 3-bromo-1,5- and ?1,7-azulenequinones has been developed by bromination of azulene in aqueous tetrahydrofuran. Reduction of 3-bromo-1,5- and ?1,7-azulenequinones with tin or zinc powder in acetic acid gave the parent 1,5- and 1,7-azulenequinones, and further reduction products.     

Pentamethylcyclopentadienyl rhodium complexes of 1,5- and 1,7-dihydro-s-indacenes and their derivatives

The reaction of (C₅Me₅RhCl₂)₂ with AgSbF₆ in the presence of 1,5- and 1,7- dihydro-s-indacenes or 2,6-dimethyl-1,5- and 1,7-dihydro-s-indacenes provides stable η⁵- or η⁶-monorhodium complexes, respectively. A novel phane rhodium complex is described.     

Directing effects of tethered alkenes in nickel-catalyzed coupling reactions of 1,6-enynes and aldehydes

Nickel-catalyzed reductive coupling reactions of aldehydes and 1,6-enynes proceed in excellent regioselectivity in the absence of a phosphine, and the use of a monodentate phosphine additive leads to the formation of the opposite regioisomer with equally high selectivity. Both products are the result of the same fundamental mechanism, with the inversion of regioselectivity being the result of stereospecific ligand substitution at the metal center.     

Reactions of tellurium tetrahalides with 1,5- and 1,6-diolefins and their derivatives

1,4-Dihalo-substituted tellurolanes were obtained by reaction of tellurium tetrabromide and tetrachloride with 1,5-hexadiene, and the corresponding six-membered heterocyclic compounds with a tellurium atom in the ring were obtained with 1,6-diolefins.Communication IV from the series Organic Selenium and Tellurium Compounds. See [1] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1212–1214, September, 1978.     

1,6- and 1,7-naphthyridines. II. Synthesis from acyclic precursors

A number of 8-hydroxy-6-methyl-1,6-naphthyridin-5(6H)-one-7-carboxylic acid alkyl esters 3 and the isomeric 5-hydroxy-7-methyl-1,7-naphthyridin-8(7H)-one-6-carboxylic acid alkyl esters 4 were synthesized from acyclic precursors obtained starting from quinolinic anhydride 5. Thus, methanolysis of 5 afforded the hemiester 6 which treated with oxalyl chloride and sarcosine ethyl ester gave 3-(N-ethoxycarbonylmethyl-N-methylcarbamoyl)pyridine-2-carboxylic acid methyl ester 8. Compound 8 was cyclized to naphthyridines 3a-e with sodium alkoxides. The isomeric naphthyridines 4a-c were obtained by cyclization of the open intermediary 2-(N-ethoxycarbonylmethyl-N-methylcarbamoyl)pyridine-3-carboxylic acid methyl ester 9 obtained by a route that involves treatment of 5 with sarcosine ethyl ester and esterification with diazomethane. Spectroscopic properties (¹H nmr, uv, ir) of compounds 3 and 4 are discussed and confirmed the proposed structures.     

A new approach to arylaliphatic 1,5-, 1,6-, and 1,7-dicarbonyl compounds and their monoacetals based on direct anodic oxidation of 1-phenyl- and benzo[c]cycloalkenes

A new simple approach to -benzoylalkanals, 2-((-formylalkyl)benzaldehydes, and their monoacetals was developed based on direct anodic oxidation of I-phenylcycloalkenes and benzo[ccycloalkenes in methanol followed by acid hydrolysis of the electrolysis products. The target products are obtained in 53–72 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2044–2046, August, 1996.     

1,6- and 1,7-naphthyridines. I. Rearrangement of quinolinimidoacetic acid derivatives

The reaction of N-substituted quinolinimides 1a-d with sodium alkoxides afforded a mixture of 1,6-naphthyridines 2 and 1,7-naphthyridines 3 which were isolated by chromatographic methods. Structure assignment for each pair of isomers was made by comparison of their ¹H nmr spectra with those of picolinamide and nicotinamide. When esters 1a -c were treated with alkoxides from primary alcohols, other than that of the ester, total transesterification took place. Experimental results suggest that transesterification occurs in open intermediary species.     

The regioselectivity of rhodium and palladium-catalysed cyclisations of 2-bromo-1,6- and -1,7-dienes

2-Bromo-l,6-dienes are catalytically cyclised to a mixture of the corresponding 3,4-bis(methylene)cyclopentane and 5-methylenecyclohex-3-ene. Wilkinson's catalyst shows good selectivity for the 5-membered ring product whilst palladium catalysts, in general, show little selectivity, Addition of tetraethylammonium salts, especially the chloride, allow the palladium catalysed reactions to be carried out at 30°C in good yield and with high selectivity for the 5-membered ring. 2-Bromo-1,7-dienes are cyclised regio-specifically to 6-membered rings by the same catalysts although some double bond isomerisation also occurs. The mechanism of the catalytic cyclisations is discussed. The 3,4-bis(methylene) cyclopentanes undergo facile Diels-Alder reactions.     

1,6- and 1,7-regioisomers of dinitro- and diamino-substituted perylene bisimides: synthesis,photophysical and electrochemical properties

1,6- and 1,7-regioisomers of dinitro- (1,6-3 and 1,7-3) and diamino-substituted perylene bisimides (1,6-1 and 1,7-1) were synthesized. The regioisomers 1,6-3 and 1,7-3 were successfully separated by high performance liquid chromatography and characterized by 500 MHz ¹H NMR spectroscopy. Subsequently, the reduction of 1,6-3 and 1,7-3 afforded the corresponding diaminoperylene bisimides 1,6-1 and 1,7-1, respectively. This is the first time 1,6-regioisomers of dinitro- and diamino-substituted perylene bisimides are obtained in pure form. The photophysical and electrochemical properties of 1,6-3 and 1,7-3 were found to be almost the same. However, the regioisomers 1,6-1 and 1,7-1 exhibit significant differences in their optical characteristics. The absorption spectrum of 1,6-1 covers a larger part of the visible region compared to that of 1,7-1. Upon excitation, 1,6-1 also show larger dipole moment change than that of 1,7-1. Time-dependent density functional theory calculations are reported on these dyes in order to rationalize their electronic structure and absorption spectra.     

1,5-Stereocontrol in tin(IV) halide promoted reactions of 2-alkoxy-1-(2-tributylstannylethylidene)cyclohexanes with aldehydes

2-Methoxy- and 2-(p-methoxybenzyloxy)-1-(2-tributylstannylethylidene)cyclohexanes 22 and 23 were prepared from 2-methoxy- and 2-(p-methoxybenzyloxy)cyclohexanones 12 and 13. The allylstannane 22 was transmetallated stereoselectively with tin(IV) chloride at −78 °C to generate an allyltin trihalide, which reacted with aldehydes to give (Z)-(3-hydroxyalkylidene)-2-methoxycyclohexanes 24 with excellent 1,5-syn-stereocontrol. Similar reactions with aldehydes were observed for the 2-(p-methoxybenzyloxy) substituted allylstannane 23. The structure of the product 24f prepared from p-nitrobenzaldehyde was confirmed by an X-ray structure determination of its p-nitrobenzoate ester 27.     

Vibrational spectra and molecular conformations of 1,5-dichloro- and 1,5-dibromopentanes and 1,6-dichloro-and 1,6-dibromohexanes

The Raman and IR spectra of 1,5-dichloro- and 1,5-dibromopentanes and 1,6-dichloro-and 1,6-dibromohexanes have been measured. The normal coordinates have been calculated for these molecules using a consistent set of force constants and the molecular conformations studied by analysing the spectra with reference to the results of the calculations. In the crystalline solid state, 1,5-dichloropentane assumes the trans-trans-trans-gauche form and 1,5-dibromopentane, 1,6-dichloro- and 1,6-dibromohexanes assume the all-trans form. The normal coordinate treatment with the well-established force field was of great help in determining the whole molecular form of the relatively large chain molecules.