54049-09-1

Upstream product

• 544-25-2 Cyclohepta-1,3,5-triene 
• 501-65-5 diphenyl acetylene 
• 161375-35-5 tricarbonyl(η(2:4)-7,8-diphenylbicyclo[4.2.1]nona-2,4,7-triene)chromium(0) 
• 108-88-3 toluene 

Relevant academic research and scientific papers

?6s + ?2s> Cyloadditions Catalysed by the TiCl4-Et2AlCl System

The catalyst system TiCl4-Et2AlCl induces ?6s + ?2s> cycloadditions of cycloheptatriene to buta-1,3-diene, norbornadiene, and acetylenes.

Rhodium-catalyzed [6 + 2] cycloaddition of internal alkynes with cycloheptatriene: Catalytic study and DFT calculations of the reaction mechanism

A rhodium-catalyzed [6 + 2] cycloaddition of internal alkynes with cycloheptatriene is described. A series of substituted alkynes were cycloadded to cycloheptatriene through a [6 + 2] addition to give a variety of substituted bicyclic compounds in excellent yields. The optimal catalytic system for these transformations was a [Rh(COD)Cl]2 (5.0 mol %) catalyst in combination with CuI (10 mol %) and PPh3 (10 mol %). The proposed mechanism for this system includes an initial oxidative coupling reaction between the coordinated cycloheptatriene and the internal alkyne, followed by a [1,3]-shift of the Rh metal center and a reductive elimination from the Rh(III)-allyl complex to give the final product. Calculations using a model Rh(I) catalyst were also carried out to further understand this mechanism.

Cobalt-catalysed [6+2] cycloaddition of internal alkynes and terminal alkenes with cycloheptatriene

The cobalt-catalysed [6+2] cycloaddition of cycloheptatriene with internal alkynes as well as with terminal alkenes is described. The cycloaddition process is most efficiently catalysed by cobalt dibromide[bis(triisopropylphosphite)] complexes in dichloro

Metal-mediated [6 + 2] cycloadditions of alkynes to cycloheptatriene and N-carbethoxyazepine

UV photolysis of [(η6-C7H7R)Cr(CO)3] (1, R = H, Ph, CH{CO2Me}2) and R?C=CR? (R? = Ph, Tol, SiMe3, Et) in toluene or n-hexane gives the [6 + 2] cycloadducts [(η2:4-C9H7{R}R?2)Cr(CO)3] (2). Heating 2 in toluene releases the 7,8-disubstituted bicyclo[4.2.1]nona-2,4,7-trienes 3 and [(η6-C6H5Me)Cr(CO)3]. Irradiation of solutions of 1 and dimethyl acetylenedicarboxylate at O °C yields the bicyclotriene as the major product but no organometallic complex. The diphenyl derivative 2a undergoes a reversible intramolecular metal migration to the η6-aryl species 4. Irradiation of the azepine complex [(η6-C6H6N{CO2Et})Cr(CO) 3] (5) and R?C≡CR? (R? = Ph, SiMe3) in toluene also forms [6 + 2] cycloadducts [(η2:4-C8H6N{CO2Et}R? 2)Cr(CO)3] (6). The heterobicyclotrienes 7 are isolated from 6 by treatment with iodine (R? = SiMe3) or by heating in toluene (R? = Ph). X-ray crystal structures are reported for 6b (R? = SiMe3) [orthorhombic, P212121, a = 8.871(1), b = 10.148(1), and c = 26.017(4) A, R = 0.041 for 2500 independent reflections] and a byproduct (8) that results from the endo [6 + 4] cycloaddition of N-carbethoxyazepine to 5; monoclinic, P21/c, a = 10.665(9), b = 14.976(7), and c = 13.004(7) A?,β= 100.05(7)°, R = 0.047 for 1044 independent reflections. Heating cycloheptatriene and alkynes R?≡CR? (R? = SiMe3, Me, Et) in dibutyl ether with a catalytic amount of Cr(CO)6 or Fe2(CO)9 also gives good yields of the [6 + 2] cycloadducts 3, whereas the thermal reaction with dimethyl acetylenedicarboxylate in the presence of Cr(CO)6 gives the known norcaradiene [4 + 2] adduct 9.

Photoinduced [6 + 2] cycloadditions of alkynes to tricarbonyl(cycloheptatriene)chromium(0)

Photolysis of [(η6-C7H8)Cr(CO)3] (1) and RC≡ CR (2a, R = Ph; 2b, R = Tol) in toluene or n-hexane results in the formation of [(η2:η4-C9H8R 2)Cr(CO)3] (3a,b) in 70-85% isolated yield via a [6 + 2] cycloaddition reaction. Heating 3a,b in toluene gives the bicyclo[4.2.1]-nona-2,4,7-trienes 4a,b and [(η-C6H6Me)Cr(CO)3]. Photolysis of 1 and excess DMAD (dimethyl acetylenedicarboxylate, 5) in toluene at 0°C yields the bicyclotriene 4c as the major product and small amounts of the arene C6(CO2Me)6 and the [4 + 2] cycloadduct between 4c and 5.

CYCLOADDITIONS CATALYZED BY TITANIUM COMPLEXES

The Ziegler catalyst TiCl4-Et2AlCl and the arenetitanium(II) complex (η6-C6H6)Ti(II)(AlCl4)2 induce cycloaddition reactions of cycloheptatriene with dienes and acetylenes.Addition to 1,3-butadiene affords 7-endo-vinyl-bicyclonona-2,4-diene (main product) and bicyclo-undeca-2,4,8-triene, a product of cycloaddition.Isoprene reacts similarly, yielding mainly 7-endo-isopropenyl-bicylonona-2,4-diene. 2,3-Dimethyl-1,3-butadiene gives 8,9-dimethylbicycloundeca-2,4,8-triene, a product of cycloaddition, while cross-adducts are minor products.The reaction of cycloheptatriene with norbornadiene gives mainly hexacyclo2.7.03.12.06.10.09.13>tetradec-4-ene via cycloaddition followed by intramolecular Diels-Alder reaction.As a by-product, pentacyclo2.7.03.5.04.8>tetradeca-10,12-diene is formed by a mechanism.Addition of cycloheptatriene to phenylacetylene and bis-(trimethylsilyl)acetylene furnishes substituted bicyclonona-2,4,7-trienes.Alkenes, E,E-2,4-hexadiene and 1,3-cyclooctadiene are unreactive.The cycloaddition is made possible by coordination of cycloheptatriene to titanium, which changes the symmetry of the frontier orbitals in the triene.The reactivity of the trienophile is also enhanced by coordination to the catalyst.