72610-85-6

Upstream product

• 72610-89-0 Lithium Salt of Benzocyclobutenone Tosylhydrazone 
• 3469-06-5 benzocyclobutenone 
• 1576-35-8 toluene-4-sulfonic acid hydrazide 

Downstream Products

• 529-19-1 2-Methylbenzonitrile 
• 3469-06-5 benzocyclobutenone 
• 69139-15-7 Sodium Salt of Benzocyclobutenone Tosylhydrazone 
• 72610-89-0 Lithium Salt of Benzocyclobutenone Tosylhydrazone 

Relevant academic research and scientific papers

THE ADDITION OF BENZOCYCLOBUTENYLIDENE TO BENZENE. THE FACILE REARRANGEMENT OF SPIRO(BENZOCYCLOBUTENE-1,7'-CYCLOHEPTA-1',3',5'-TRIENE) TO 9a,10-DIHYDROBENZ(a)AZULENE

Thermal decomposition of the sodium salts of benzocyclobutenone tosylhydrazone and 2-methylbenzocyclobutenone tosylhydrazone in benzene affords 9a,10-dihydrobenz(a)azulene 4 and trans-10-methyl-9a,10-dihydrobenz(a)azulene 3, respectively.A mechanism involving initially the addition of the carbene benzocyclobutenylidene, or its 2-Me derivative, to the benzene ring is postulated.A proposed intermediate in the reaction, spiro(benzocyclobutene-1,7'-cyclohepta-1',3',5'-triene) 12 has been synthesised, and shown to give rise to 4 under the reaction conditions.The rate of rearrangement of 12 -> 4 has been measured, and the activation energy determined: Ea = 125.9 +/- 0.8 kJmol-1 and A = 1.38*1014 sec-1.The mechanism for the rearrangement must involve ring opening of the benzocyclobutene moiety of 12 to give an o-xylylene intermediate which is postulated to possess considerable diradical character.At 71.8 deg C this ring opening is 2.7*106 times faster than the ring opening of the parent benzocyclobutene molecule.The decomposition of the sodium salt of 2-(7'-cyclohepta-1',3',5'-trienyl)benzaldehyde tosylhydrazone has also been investigated, and is shown to yield 4a,10-dihydrobenz(a)azulene, 9,10-dihydrobenz(a)azulene and 8,9-benzotricyclo(5.3.0.02.10)deca-3,5,8-triene.A mechanism involving intramolecular 1,3-dipolar addition of a diazo grouping to a cycloheptatriene Π-bond, followed by decomposition of the resulting pyrazoline intermediate, is proposed.

Benzocyclobutenylidene-Cycloadditions, Reactivity, and Multiplicity

EHT and CNDO/2 calculations on benzocyclobutenylidene (6) are described.Flash pyrolysis of the tosylhydrazone salt 7 affords benzocyclobutene and o-xylene in low yield, along with the formal syn and anti carbene dimers 13 and 14.Condensed-phase reactions were achieved by photolysis of the salt 15.Benzocyclobutenylidene (6) gave rise to the formal carbene dimers 17 and 18.Insertion of carbene 6 into the carbon-hydrogen bonds of 2,3-dimethylbutane produced the benzocyclobutenes 20 and 21 (insertion ratio tertiary:primary = 9:1).Cycloaddition of 6 to olefins gave only spirohexene derivatives 22.Multiplicity studies of 6 with cis or trans olefins indicated that 6 undergoes cycloaddition in a stereospecific manner.Competition experiments using dienes and monoolefins implicate an equilibrium between singlet and triplet 6.Further competition experiments with styrene/para-substituted styrene pairs demonstrated that 6 reacts faster with electron-poor styrenes.Possible explanations for this apparent anomaly are discussed.