Lithiation of the 6-dimethylamino-1-azafulvene dimer. A versatile synthesis of 5-substituted pyrrole-2 carboxaldehydes.

Acortatarins A and B have been synthesized via stereoselective spirocyclizations of glycals. Mercury-mediated spirocyclization of a pyrrole monoalcohol sidechain leads to acortatarin A. Glycal epoxidation and reductive spirocyclization of a pyrrole dialdehyde sidechain leads to acortatarin B. Acid equilibration and crystallographic analysis indicate that acortatarin B is a contrathermodynamic spiroketal with distinct ring conformations compared to acortatarin A.

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“…14 The pyrrole dicarboxaldehyde 9 15, 16 was then coupled under biphasic conditions 17 to afford the key pyrrologlycal 10 .…”

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confidence: 99%

Stereoselective Synthesis of Acortatarins A and B

2012

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“…All common reagents and solvents were obtained from commercial suppliers and used without any further purification unless otherwise indicated. Fischer carbene complexes 2,3 [2i, 3f, 32] and the diazafulvene 1 [22] were prepared by following the described procedures. Solvents were dried by standard methods and distilled prior to use.…”

Section: Methodsmentioning

confidence: 99%

“…[21] Secondly, surprisingly few reports exist on the use of azafulvenes in heterocyclic synthesis. [22] Specifically, we thought of the 1,4-diazafulvene structure as a reactive imidazole building block Abstract: We examined the reactivity of dimethylaminodiazafulvene 1 toward Fischer alkenylcarbene 2 and alkynylcarbene 3 complexes. Diazafulvene 1 reacts with alkenylcarbenes 2 through a formal [6+3] heterocyclization in a regio-and stereoselective manner to afford dihydroimidazo [1,2-a]pyridines 4.…”

Section: Introductionmentioning

confidence: 99%

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Facile and Versatile Annulation of the Imidazole Ring: Single and Sequential Cyclization Reactions of Fischer Carbene Complexes with 1,4‐Diazafulvenes

Barluenga¹,

García-Rodríguez²,

Martı́nez³

et al. 2006

Chemistry A European J

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We examined the reactivity of dimethylaminodiazafulvene 1 toward Fischer alkenylcarbene 2 and alkynylcarbene 3 complexes. Diazafulvene 1 reacts with alkenylcarbenes 2 through a formal [6+3] heterocyclization in a regio- and stereoselective manner to afford dihydroimidazo[1,2-a]pyridines 4. Acid-promoted dimethylamine elimination in compound 4 c gives rise to the aromatic imidazo pyridine 5. A likely mechanism for this reaction is a 1,2-nucleophilic addition/[1,2]-shift metal-promoted cyclization sequence. On the other hand, diazafulvene 1 and alkynyl carbenes 3 undergo a [6+2] cyclization to afford pyrrolo[1,2-a]imidazole carbene complex 6 that can be readily oxidized to the corresponding esters 7. When enynylcarbenes 3 e-i are treated with diazafulvene 1, consecutive and diastereoselective [6+2]/cyclopentannulation cyclization reactions take place affording new polycyclic complex systems 8, 9, and 12 that can be appropriately demetallated to the corresponding imidazole-based polyfused systems 10, 11, and 13 respectively. Finally, enynylcarbenes 3 d,f undergo consecutive [6+2]/[5+1] cyclization reactions with diazafulvene 1 and tBuNC, respectively, to yield tetracyclic adducts 14 and 15. All these processes result in high yields and provide a route to the preparation of imidazopyridines and pyrroloimidazoles as well as other polycyclic molecules that contain imidazole groups, which are interesting from a pharmacological and biological point of view.

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“…The synthesis of analogs 13, 14, 15, and 16 started with the preparation of 5-(tri-n-butylstannyl)pyrrole-2-carboxaldehyde (10) from commercial available pyrrole 2-carboxaldehyde 8 [11] via the known compound 9a [12] (Scheme 1). First, an aqueous solution of dimethyl amine was reacted with pyrrole-2carboxaldehyde (8) that yielded azafulvene 9a in a quantitative yield.…”

Section: Synthesismentioning

confidence: 99%

Synthesis of mycalazol and mycalazal analogs with potent antiproliferating activities

Mohamed

Hansen

2011

Pure and Applied Chemistry

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Four 2,5-disubstituted pyrrole and two 2-disubstituted thiophene analogs of the natural products mycalazol 5 and mycalazal 2 have been prepared using the Stille coupling reaction. All four analogs displayed potent antiproliferating activity against several human cancer cell lines with IC 50 values in the nanomolar range.Scheme 2 Synthesis of mycalazol 5 and mycalazal 11 analogs.Scheme 3 Synthesis of thiophene analogs 18 and 19.

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Lithiation of the 6-dimethylamino-1-azafulvene dimer. A versatile synthesis of 5-substituted pyrrole-2 carboxaldehydes.

Cited by 38 publications

References 9 publications

Stereoselective Synthesis of Acortatarins A and B

Stereoselective Synthesis of Acortatarins A and B

Facile and Versatile Annulation of the Imidazole Ring: Single and Sequential Cyclization Reactions of Fischer Carbene Complexes with 1,4‐Diazafulvenes

Synthesis of mycalazol and mycalazal analogs with potent antiproliferating activities

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