The Solvolysis of 4α- and 4β-Methylcholesteryl p-Toluenesulfonate<sup>1a</sup>

Moriarty, Robert M.; Sousa, Rose Marie de

doi:10.1021/jo01046a034

Cited by 10 publications

(8 citation statements)

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“…It is not excluded that such a peak character is caused by the existence of 1 as a mixture of conformers that differ by a rotation angle around the N-COCH 3 bond (cf. [15] ) and reduced at somewhat different potential values. From the analysis of the potential values, the pentafluorophenyl moiety is most likely the electron receptor, rather than the acetyl group.…”

Section: N-acetylation Deblocking Effectmentioning

confidence: 96%

N‐Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho‐Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles

et al. 2006

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Keywords: Amides / Hydrodefluorination / Ab initio calculations / Nitrogen heterocycles / Zinc N-Acetylation of polyfluoroarylamines is proposed as a means to remove the amino group blocking effect of their hydrodefluorination by zinc in aqueous ammonia. With pentafluoroacetanilide, the Zn ion specific effect has been demonstrated to be responsible for ortho hydrodefluorination. This regiochemistry is accompanied by the removal of a fluorine atom from the para position, which occurs predominantly in the initial phase of the process in the absence of deliberately added zinc salt. The CuCl 2 additive has been found to accelerate the reaction and to propel it to double defluorination. Quantum chemical calculations suggest a diminished electron affinity of pentafluoroaniline, which is responsible for its inertness in relation to the hydrodefluorination reaction. The pentafluoroaniline radical anion, which essentially has a nonplanar structure, is prone to easy fragmentation to give an aminotetrafluorophenyl radical. For pentafluoroacetani-

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Section: N-acetylation Deblocking Effectmentioning

confidence: 96%

N‐Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho‐Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles

et al. 2006

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“…13 [18] According to continuous-flow procedure A, morpholine (0.5 mmol, 43.3 μL) gave compound 8f 32 (m, 12 H), 0.81 (t, J = 6.5 Hz, 3 H) ppm. 13 N-Phenyldecanamide (8k): [15] According to continuous-flow pro- 13 N,N-Diallyldecanamide (8m): [19] According to continuous-flow procedure A, diallylamine (0.5 mmol, 61.7 μL) gave compound 8m Benzylacetamide (9a): [20] According to continuous-flow procedure B, benzylamine gave compound 9a [23] [24] N-Cyclohexylacetamide (9g): [25] N-Cyclohexyl-N-methylacetamide (9h): [26] According [27] Octyldecanoate (10b): [32] According to continuous-flow procedure C, Isopropyl Decanoate (10e): [33] According to continuous-flow procedure C, isopropanol gave compound 10e (0.071 g, 66 %) as a yellow oil. IR: ν = 2924 (s), 1732 (s), 1108 (s) cm -1 .…”

Section: -Tert-butoxydec-1-yne (3b)mentioning

confidence: 99%

Generation and Trapping of Ketenes in Flow

et al. 2015

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Ketenes were generated by the thermolysis of alkoxyalkynes under flow conditions, and then trapped with amines and alcohols to cleanly give amides and esters. For a 10 min reaction time, temperatures of 180, 160, and 140 °C were required for >95 % conversion of EtO, iPrO, and tBuO alkoxyalkynes, respectively. Variation of the temperature and flow rate with inline monitoring of the output by IR spectroscopy allowed the kinetic parameters for the conversion of 1-ethoxy-1-octyne to be easily estimated (Ea = 105.4 kJ/mol). Trapping of the in-situ-generated ketenes by alcohols to give esters required the addition of a tertiary amine catalyst to prevent competitive [2+2] addition of the ketene to the alkoxyalkyne precursor.

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“…Other bicyclo [2.2.1] cases (e.g. 19) are similarly valued upward (e.g., 5, +1.6 eV; 19, + 1.2 eV) leading to the result that tt(NN) in 2 is most likely pulled artificially below es. It appears, therefore, that while the relative values of hydrocarbon and hydrocarbonfragment IP's may be qualitatively reproduced by semiempirical schemes,23a,31b•35 the introduction of strongly electronegative atoms can, in certain cases, lead to completely misleading predictions.…”

Section: Assignment Of the Diazadeltacyclene Pe Spectrummentioning

confidence: 99%

“…The relative rates of nitrogen extrusion from polycyclic azoalkanes have been investigated for systems represented by structures [16][17][18][19] (cf. Table III).…”

Section: Homoconjugation and Reactivity In Polycyclic Azoalkanesmentioning

confidence: 99%

Photoelectron spectra of diazabasketene, diazadeltacyclene, and related polycyclic cis-azoalkanes

Boyd¹,

Bünzli²,

Snyder³

1976

J. Am. Chem. Soc.

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The He(1) photoelectron spectra of diazabasketene (Z), the cyclobutanated [2.2.2] system 3, and diazadeltacyclene (5) are reported. For all three substances level assignments lead to the MO sequence: n-> P > n+. In order to assist with the assignment of diazabasketene, the PE spectrum of basketene has been measured. Unlike the situation for simple cis-azo bicyclics, high-lying CT orbitals associated with the cyclopropane and cyclobutane moieties fall between n-and ?r(NN). The orbital interactions responsible are simultaneously the cause for a n-/n+ splitting of about 3.8 eV for diazabasketene and 4.0 eV for diazadeltacyclene. These values are the largest so far observed for cis-azoalkanes. The importance of ground-state homoconjugation for multicyclic azo compounds containing three-and four-membered rings is discussed in terms of molecular conformation and nitrogen extrusion rates. Caution is urged in the application of PES determined MO sequences to the relative energy of the corresponding transition states for retrocycloaddition reactions involving nitrogen. The partial determination of structural parameters for the title compounds and complete determination for some related bicyclics by MO calculations are discussed. And finally a problem associated with the interpretation of the PE spectra of large molecules is described.The study of the electronic structure of organic molecules and the rationalization of the pathways of chemical reactions have been given new impetus recently by the work of F~k u i ,~~ H~f f m a n n ,~~ P e a r~o n ,~~ and others4 on orbital interactions. These interactions are either intermolecular or intramolecular in nature. The former provide the basis for various set^^.^ of symmetry rules for chemical reactions which have been applied with considerable success to a large variety of systems. Intramolecular interactions are especially interesting in molecules which have two or more localized, or semilocalized, orbitals of the A bonding and lone pair types. These localized orbitals, or groups of localized orbitals, may interact either directly or indirectly with each other. The relative importance of these two modes of interaction, known as through-space and through-bond ,interaction, respectively, can only be evaluated by means of molecular orbital (MO) calculations whereas the magnitude of the splitting associated with the interaction of two localized orbitals can be investigated experimentally by photoelectron spectroscopy (PES).In this paper we are concerned with the interaction of lone pair orbitals on adjacent nitrogen atoms and their further interaction with various three-and four-membered ring carbon units in a multicyclic molecular frame. PES has been used to determine the splitting between the symmetric combination of lone pair orbitals n+ and the antisymmetric combination n-in diimide,6 trans-azomethane,' diazirine,x several aliphatic cyclic and multicyclic cis-and trans-azo m o l e c~l e s ,~-~ and As a sequel to our earlier study l o of the 2,3-diazabicyclo[2.2.n]alk-2-enes (n ...

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The Solvolysis of 4α- and 4β-Methylcholesteryl p-Toluenesulfonate^1a

Cited by 10 publications

References 0 publications

N‐Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho‐Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles

N‐Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho‐Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles

Generation and Trapping of Ketenes in Flow

Photoelectron spectra of diazabasketene, diazadeltacyclene, and related polycyclic cis-azoalkanes

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The Solvolysis of 4α- and 4β-Methylcholesteryl p-Toluenesulfonate1a

Cited by 10 publications

References 0 publications

N‐Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho‐Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles

N‐Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho‐Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles

Generation and Trapping of Ketenes in Flow

Photoelectron spectra of diazabasketene, diazadeltacyclene, and related polycyclic cis-azoalkanes

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The Solvolysis of 4α- and 4β-Methylcholesteryl p-Toluenesulfonate^1a