7-Selenabicyclo[2.2.1]heptane

Thermolysis of a benzene solution of N-[4-(p-(methoxybenzyl)seleno)cyclohexanoyl]-N,S-dimethyldithiocarbonate affords the hitherto unknown 7-selenabicyclo[2.2.1]heptane in 48% conversion and in 20% yield after chromatography. G3(MP2)-RAD calculations predict a rate constant of 5 × 10(4) s(-1) at 80 °C (3.8 × 10(6) s(-1) at 200 °C) for the intramolecular homolytic substitution process involved in this cyclization.     

Syntheses and tandem Diels-Alder reactivities of 7,7-diphenyl-[2.2.1]hericene (= 7-(diphenylmethylidene)-2,3,5,6- tetramethylidenebicyclo[2.2.1]heptane) and 7-oxa[2.2.1]hericene ( = 2,3,5,6-tetramethylidenebicyclo[2.2.1]heptan-7-one)

Syntheses of 7,7-diphenyl[2.2.1]hericene ( 4 ) and 7-oxa[2.2.1]hericene ( 5 ) are presented. Rate constants k₁ and k₂ of the two successive Diels-Alder additions of ethylenetetracarbonitrile (TCE) to 4 and to 5 have been evaluated. At 25° in toluene, the rate-constant ratio k₁/k₂ = 260 and 21 for 4 and 5 , respectively. These results are compared with those reported for the tandem Diels-Alder reactivity of 2,3,5,6-tetramethylidenebicyclo[2.2.1]heptane and other derivatives.     

Chiral 7-Oxabicyclo[2.2.1]heptane Building Blocks for Prostanoids

Russian Journal of Organic Chemistry - Methyl (Z)-3-[(2R,3R,4S,5S)-5-(2-methoxy-2-oxoethyl)-3,4-(isopropylidenedioxy)tetrahydrofuran-2-yl]-prop-2-enoate was synthesized, and its intramolecular...     

7-oxabicyclo[2.2.1]heptane hydrochloride and hydrofluoride: Quantum-chemical investigation

Structural parameters, IR spectra and energy of H-bonds for binary complexes of 7-oxabicyclo[2.2.1]heptane molecule with molecules of HCl and HF are calculated by quantum-chemical B3LYP/cc-pVTZ method with inclusion to the basis of diffuse “aug”-orbitals of halogen, oxygen and bridgehead hydrogen.     

Enzymatic preparation of optically active 7-oxabicyclo[2.2.1] heptane derivatives

Enzymatic resolution of endo-7-oxabicyclo [2.2.1] hept-2-yl butyrates 3 and 5 using lipase from Candida cylindracea led to optically pure bicyclic alcohols and esters being important intermediates for the synthesis of biologically active compounds.     

1‐Phosphabicyclo[2.2.1]heptane

1‐Phosphabicyclo[2.2.1]heptanes Exo‐endo‐ and exo‐exo‐2.6‐dimethyl‐1‐phosphabicyclo [2.2.1]heptane have been obtained by cyclization of 2‐methyl‐4‐(2‐propenyl)phospholane in the presence of the complex base, sodium salt of diethylenglycolmonoethylether ‐ sodium amide in THF (NAMEDEG). The bicyclic phosphanes are characterized by reac‐tions with selenium, sulfur, (CH₃)₂SeO, CH₃I and HSO₃F, respectively, elemental analysis, X‐ray crystal structure analysis as well as ¹H, ¹³C, ³¹P NMR spectral measurements. The steric demand of these phosphanes as complex ligands has been estimated from the P, H coupling constants of the phosphonium fluorosulphates according to the Tolman model. The phosphane selenides were found to display the lowest values for the ¹J(Se, P) coupling constant, found up to now for alicyclic and cyclic aliphatic tertiary phosphane selenides. The ⁿJ(P, H)‐ and ⁿJ(H, H)_{n=2, 3} coupling constants have been extracted from the proton spectra at 600 MHz by computerized analysis.     

Synthesis and free radical polymerization of 2-methylene-7-oxabicyclo[2.2.1]heptane

A new monomer, 2-methylene-7-oxabicyclo[2.2.1]heptane ( IV ) was synthesized via four steps. Its structure was confirmed by IR, ¹H-NMR, and ¹³C-NMR spectra as well as elementary analysis. Free radical polymerization and copolymerization of IV were investigated. No homopolymer was obtained due to the effect of allyl inhibition. When IV copolymerized with electron-donor monomers, such as vinyl acetate and stvrene, IV acted as inhibitor for the polymerization of vinyl acetate, but could not inhibit the polymerization of styrene. However, the copolymers of IV with electron-accepting monomers, such as methyl methacrylate, acrylonitrile, or maleic anhydride (MA) were obtained. The contents of IV in the copolymers increased as e values of electron-accepting monomers increased. Strictly alternating copolymer was obtained only in the case of MA and IV . The thermal properties of copolymers were investigated. © 1995 John Wiley & Sons, Inc.     

Über 1.4-Dialkyl-3-acetoxy-7-acetamido-2-oxabicyclo[2.2.1]heptane

Zusammenfassung 2.5-Dialkyl-3.4-dihydro-2H-pyran-2-aldehyde (1 c–1 f) setzen sich mit Acetamid und Essigsäureanhydrid zu 2,5-Dialky-3.4-dihydro-2H-pyran-2-methandioldiacetaten (2 c–2 f), N.N-[(2.5-Dialkyl-3.4-dihydro-2H-pyran-2-yl)-methylen]bisacetamiden (3 c–3 f) und zu 1.4-Dialkyl-3-acetoxy-7-acetamido-2-oxabicyclo[2.2.1]heptanen (6 c–6 f) um. Ausdem 3.4-Dihydro-2H-pyran-2-aldehyd (1 a) entsteht unter gleichen Bedingungen kein Oxabicycloheptan. Mit Methylharnstoff reagieren die genannten Pyranaldehyde zu Pyranylmethylenbismethylharnstoffen9 c–9 f.

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1.4-dialkyl-3-acetoxy-7-acetamido-2-oxabicyclo[2.2.1]heptanes

2.5-Dialkyl-3.4-dihydro-2H-pyran-2-carboxaldehydes (1 c to1 f) are transformed by acetamide and acetic anhydride to 2.5-dialkyl-3.4-dihydro-2H-pyran-2-methanediol diacetates (2 c to2 f), N.N-[(2.5-dialkyl-3.4-dihydro-2H-pyran-2-yl)-methylen] bisacetamides (3 c–3 f) and to 1.4-dialkyl-3-acetoxy-7-acetamido-2-oxabicyclo[2.2.1]heptanes (6 c–6 f). 3.4-dihydro-2H-pyran-2-carboxaldehyde (1 a) is not converted to an oxabicycloheptane under the same conditions. With methylurea the pyranaldehydes mentioned react to pyranylmethylenebismethylureas9 c–9 f.

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Herrn Prof. Dr.M. Pailer zum 60. Geburtstag gewidmet.     

N-Arylmethyl-7-azabicyclo[2.2.1]heptane derivatives: synthesis and reaction mechanisms

N-Arylmethyl-7-azabicyclo[2.2.1]heptane (I) derivatives have been synthesized by deprotection of N-protected, N-(arylmethyl)cyclohex-3-enamines, bromination of the resulting secondary cyclohex-3-enamines, followed by base-promoted cyclization (route a), or by bromination of N-protected, N-(arylmethyl)cyclohex-3-enamines followed by deprotection and base-mediated cyclization (route b). In these protocols we have observed that the bromination of the key intermediates (12, 13, and 19) is stereoselective leading to major trans-3-cis-4-dibromides (14, 17, and 20), whose mild base-mediated heterocyclization (on compound 14), or the two-step acid hydrolysis plus base-promoted cyclization (on compounds 17 and 20), gave products 6 and 7 in good yield. A mechanistic investigation using DFT has been carried out to explain the results observed in this work.     

Efficient synthesis of a 7-azabicyclo[2.2.1]heptane based GlyT1 uptake inhibitor

An efficient synthetic route based on generation and subsequent electrophilic reaction of a Boc-protected azabicyclo[2.2.1]heptane anion to prepare a potent GlyT1 uptake inhibitor (1) is described.     

Derivatives of 7-Oxabicyclo[2.2.1 ]hept-5-ene and 7-Oxabicyclo[2.2.1 ] heptane. Synthesis,transformations, and stereochemistry using nmr methods

Synthesis and stereochemistry of various endo-2- and exo-2-substituted-7-oxabicyclo[2.2.1]-hept-5-enes and -heptanes are described. The nmr spectra of several derivatives are reported and discussed. Use is made of this data to allow determination of the stereochemical integrity of the system. Facile chromatographic separation methods were found for endo- and exo-2-sub-stituted-7-oxabicyclo[2.2.1 ]hept-5-enes and -heptanes.     

Mass spectral studies on 7-azabicyclo (2.2.1) heptane systems

An attempt has been made to rationalise the major fragmentation modes of a few C₂, C₃ disubstituted 7-p-toluene sulphonyl and 7-carbobenzyloxy-7-azabicyclo (2.2.1) heptanes.