104599-50-0

Upstream product

• 931-53-3 Cyclohexyl isocyanide 

Relevant academic research and scientific papers

Organic Syntheses via Transition Metal Complexes, 58. - Heptafulvenylcarbene Complexes of Chromium and Tungsten. - Azaspiro Anellation to 1-Metalla-1,3-dienes with Isocyanides; Displacement of Ligands by Pyridine or by Thermolysis

(Cycloheptatrien-1-ylmethyl)carbene complexes LnM = C(OEt)CH2-c-C7H7 3 a), W(CO)5 (b)> are transformed into heptafulven-8-ylcarbene complexes LnM = C(OEt)CH=c-C7H7 5 into two steps.The first step involves the formation of (tropyliummethyl)carbene complexes + - 4 by a hydride abstraction from the cycloheptatriene ring of 3 with + - (4a, 4b: 70percent). 4 is deprotonated with Et3N to give 5 (5a: 89percent; 5b: 92percent). 5 adds one equivalent of cyclohexyl isocyanide (6) to the LnM=C-C=C unit via the intermediate ketenimine complexes LnM 7, which cyclize spontaneously and form the (thermolabile) azaspiroundecatetraene complexes 8 (8a: 91percent; 8b: 93percent).The reaction of 8a, b with pyridine leads to the disengagement of a pyrrole 10 in almost quantitative yields.Thermolysis of 8a, b in the absence of pyridine gives an azulene 12. Key Words: Heptafulven-8-ylcarbene complexes of chromium and tungsten / (Tropyliummethyl)carbene complexes of chromium and tungsten / Pyrrolylidene complexes, by electrocyclisation of C-alkenylketenimine complexes / 1-Metalla-1,3-diene, azaspiro anellation to / Disengagement of ligands with pyridine / 1-Amino-2-alkoxy-azulenes

Organic Syntheses via Transition Metal Complexes, 17. A Novel Route to Pyrroles. - Template Syntheses with Alkenylcarbene Complexes and Isocyanides via 1-Aza-pentatriene- and 1-Aza-heptatetraene Complexes

Alkenylcarbene complexes 4a, b add isocyanides R2-NC (5a - c) to give 1-aza-1,2,4-pentatriene- or 1-aza-1,2,4,6-heptatetraene complexes 6a - d, which are suitable as building blocks for syntheses of pyrrols (via an intramolecular cycloaddition), carbocyclic five-(via cycloaddition) or six-membered rings (via cycloaddition) as well as 3-imidazolines.The reactivity of 6 strongly depends on steric influences of the N-alkylgroup R2: 6a (R2 = c-C6H11) smoothly isomerises at 25 deg C to give a dihydropyrrolylidene complex 7a, which on heating to 100 deg C liberates 3-ethoxypyrrole 8a.On the other hand, 6b (R2 = C(CH3)3) no longer shows a tendency for isomerisation, but instead adds a second molecule of 5b at the metal to disengage 1-aza-1,2,4-pentatriene 10.This adds maleic anhydride in a fashion with formation of an amino-ethoxy-cyclohexadiene 14, which can be easily oxidised on air to give the amino-ethoxy-phthalic anhydride 15.A third type of reactivity predominates with 6c (R2 = CH3) in which case a second molecule of 5c adds to the ketene imine ligand, thus leading to a dark blue bis(imino)cyclopentene 16a and a yellow 3-imidazoline complex 17.This cyclisation involves a metal-induced anomalous insertion of a C=N bond into an α-CH bond of the NCH3 group.