82934-23-4Relevant academic research and scientific papers
Thermolysis and Photolysis of the Azoalkane 4,5-Diaza-7,8,8-trimethyltricyclo3,7>non-4-ene: 1,3-Diradical and Diazoalkane Formation
Adam, Waldemar,Gillaspey, William D.,Peters, Eva-Maria,Peters, Karl,Rosenthal, Robert J.,Schnering, Hans Georg von
, p. 580 - 586 (2007/10/02)
On benzophenone-sensitized photolysis at 350 nm the azoalkane 3 denitrogenates exclusively into 2,3,3-trimethyltricyclo2,6>heptane (5), while direct photolysis at 350 nm affords the tricycloheptane 5 as major product and 2,3,3-trimethyl-4-vinylcyclopentene (6) as minor product.With increasing temperature the vinylcyclopentene 6 increases in the direct photolysis.On preparative laser photolysis at 333 nm the diazo-2-(2,3,3-trimethylcyclopenten-4-yl)ethane (8) accumulates, which on subsequent photolysis is shown to produce the vinylcyclopentene 6 via the corresponding carbene intermediate.The diazoalkane 8 does not cyclize back to the azoalkane 3.The thermolysis leads essentially quantitatively to the tricycloheptane 5, with only traces of the vinylcyclopentene 6.These results are rationalized mechanistically in terms of a diazenyl diradical as common intermediate for all three denitrogenation modes.It is proposed that the divergent chemical behavior of the diazenyl diradicals produced in the three forms of activation (triplet-sensitized and direct photolysis and thermolysis) is best understood in terms of distinct spin multiplicities and electronic configurations of the diradical intermediates.In this tritopic process it is shown by means of a Salem diagram that the D?,? diazenyl diradical serves as precursor to the tricycloheptane 5 via the 1,3-diradical 4, while the D?,? diradical is responsible as intermediate for the vinylcyclopentene 6 via the diazoalkane 8.
Reaction of 4-Phenyl-1,2,4-triazoline-3,5-dione (PTAD) with Bicyclic Monoterpenes
Adam, Waldemar,Lucchi, Ottorino De,Hill, Karlheinz
, p. 1982 - 1989 (2007/10/02)
The cycloaddition of the bicyclic monoterpenes camphene (4), α-pinene (5), β-pinene (6), 2-carene (7), bornene (8), and tricyclane 9 with PTAD was investigated.Only camphene and α-pinene gave rearranged urazoles (11, 14) via dipolar cycloaddition.Ene-reaction was the predominant reaction course for α-pinene (->15) and the exclusive route for β-pinene (->16) and 2-carene (->17).Steric hindrance by the gem-dimethyl group prevents cycloaddition of bornene.The cyclopropane rings in the tricyclane 9 and 2-carene are not sufficiently strained to undergo ?+2?>cycloa ddition with PTAD.None of the monoterpenes gave ?+2?>-cycloaddition.
