Mechanism of the thermal extrusion of sulfur dioxide from (.eta.5-cyclopentadienyl)cobalt .eta.4-thiophene 1,1-dioxides to complexed cyclobutadienes

Drage, James S.; Vollhardt, K. Peter C.

doi:10.1021/om00121a034

Cited by 19 publications

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“…[59,60] Several methods can be applied to generate cyclobutadiene, as illustrated by the selected examples which involve an extrusion step from a preformed heterocyclopentadiene derivative. [61][62][63][64] NMR investigations: The identities of 6, 7 and iso-8 were confirmed by high-resolution mass spectrometry and NMR spectroscopy. The assignments of the 21-silaphlorin resonances, which are given above selected groups of peaks in Figure 2, were made on the basis of relative intensities and detailed two-dimensional NMR studies (COSY, NOESY, Consequently, density functional theory (DFT) studies were used to visualise the suggested structures of 21-silaphlorin and iso-carbacorrole and to assess the degree of macrocycle distortion that is necessary to form such macrocycles.…”

Section: Synthesis and Characterisation Of 21-silaporphyrinoidsmentioning

confidence: 86%

Reactivity of Silole within a Core‐Modified Porphyrin Environment: Synthesis of 21‐Silaphlorin and its Conversion to Carbacorrole

Skonieczny

Latos‐Grażyński

Szterenberg

2008

Chemistry A European J

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Condensation of 1,1-dimethyl-3,4-diphenyl-2,5-bis(p-tolylhydroxymethyl)silole with pyrrole and p-tolylaldehyde did not form the expected 21,21-dimethyl-2,3-diphenyl-5,10,15,20-tetra(p-tolyl)-21-silaporphyrin, but rather its reduced derivative, 21-silaphlorin, which contains a tetrahedrally hybridised C5 carbon atom. Attempts to trap 21-silaporphyrin resulted in the serendipitous discovery of a unique transformation of 21-silaphlorin into a non-aromatic isomer of 2,3-diphenyl-5,10,15,21-tetra(p-tolyl)-carbacorrole (iso-carbacorrole). This novel carbaporphyrinoid contains a cyclopentadiene ring embedded in a tripyrrolic framework. This transformation of 21-silaphlorin to iso-carbacorrole, carried out under oxidative conditions, involves extrusion of dimethylsilylene accompanied by migration of the C(meso)-(p-tolyl) unit to create a cyclopentadiene ring directly linked to the adjacent pyrrole through a tetrahedral carbon atom. Insertion of silver or copper ions into iso-carbacorrole gave two structurally related organometallic complexes of "true" carbacorrole in which the metal(III) ions are bound by three pyrrolic nitrogen atoms and a tetrahedrally hybridised C21 atom of the cyclopentadiene moiety. In the presence of oxygen, the silver(III) carbacorrole undergoes internal oxidation to 21-oxacorrole. The structure of silver(III) carbacorrole was determined by X-ray crystallography. The C21 atom was found to have a tetrahedral geometry. The Ag-C(sp(3)) (2.046(5) A) bond length is similar to that in silver(III) carbaporphyrinoids in which a trigonal carbon atom coordinates to the metal ion. Density functional theory was applied to model the molecular and electronic structure of 21-silaphlorin and feasible isomers of carbacorrole. The total energies (kcal mol(-1) vs. iso-carbacorrole), calculated at the B3LYP/6-31G(**)//B3LYP/6-31G(*) level for carbacorrole, iso-carbacorrole, vacataporphyrin and cyclobutadienephlorin, demonstrate the energetic preference for iso-carbacorrole.

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Section: Synthesis and Characterisation Of 21-silaporphyrinoidsmentioning

confidence: 86%

Reactivity of Silole within a Core‐Modified Porphyrin Environment: Synthesis of 21‐Silaphlorin and its Conversion to Carbacorrole

Skonieczny

Latos‐Grażyński

Szterenberg

2008

Chemistry A European J

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“…NaHCO 3 solution (40 mL) and dried with MgSO 4 . After evaporation of all volatile components in vacuo 10 was obtained as a yellow crystalline solid; yield 1.420 g (10.13 mmol, 98 %) (compound 10 was identified by 1 H NMR spectroscopy, by comparison with data from the literature [9] …”

Section: Methodsmentioning

confidence: 99%

Novel Dithienylethenes with Extended π‐Systems: Synthesis by Aldol Condensation and Photochromic Properties

2010

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Extrusion Reactions Affording Aromatic Systems, Dienes and Polyenes

Guziec

2022

Organic Reactions

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Extrusion reactions may be defined as chemical reactions in which an atom or small molecular fragment Y connected to two other atoms W and Z is lost from a molecule, leading to a product in which W becomes directly bonded to Z. Cheletropic reactions that afford aromatic or conjugated π systems by loss of a stable atomic or molecular fragment have also been classified as extrusion reactions. Typically, the fragments liberated in these reactions are small, stable inorganic molecules or atoms such as carbon monoxide, carbon dioxide, sulfur, sulfur monoxide, sulfur dioxide, selenium, tellurium, oxygen and nitrogen. This chapter primarily deals with the synthesis of arenes, heterocycles, 1,3‐dienes and polyenes using such extrusion processes. The utility of these reactions in the synthesis of sterically hindered molecules, dendrimers, pheromones, and other natural products are highlighted. The use of extrusion reactions for the “Click and Release” approach in drug development is also introduced.

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Mechanism of the thermal extrusion of sulfur dioxide from (.eta.5-cyclopentadienyl)cobalt .eta.4-thiophene 1,1-dioxides to complexed cyclobutadienes

Cited by 19 publications

References 2 publications

Reactivity of Silole within a Core‐Modified Porphyrin Environment: Synthesis of 21‐Silaphlorin and its Conversion to Carbacorrole

Reactivity of Silole within a Core‐Modified Porphyrin Environment: Synthesis of 21‐Silaphlorin and its Conversion to Carbacorrole

Novel Dithienylethenes with Extended π‐Systems: Synthesis by Aldol Condensation and Photochromic Properties

Extrusion Reactions Affording Aromatic Systems, Dienes and Polyenes

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