98816-49-0Relevant articles and documents
Synthesis, Thermolysis, and Photolysis of the Azoalkanes Spiro3,7>non-4-ene-8,2'-dioxolane> and 4,5-Diazatricyclo3,7>non-4-en-8-one: On the Mechanism of the Oxadi-?-methane Rearrangement of 5-Norbornen-2-one
Adam, Waldemar,De Lucchi, Ottorino,Hill, Karlheinz,Peters, Eva-Maria,Peters, Karl,Schnering, Hans Georg von
, p. 3070 - 3088 (2007/10/02)
4,5-Diazatricyclo3,7>non-4-en-8-one (4) and spiro3,7>non-4-ene-8,2'-dioxolane (5) were prepared starting from bicyclohept-5-en-2-one (1) by cycloaddition with 4-phenyl-4H-1,2,4-triazole-3,5-dione (PTAD) to the corresponding urazole 7, followed by the acetalization to the urazole 9 and subsequent hydrolysis and oxidation.The regioselectivity of the PTAD-cycloaddition leading to urazole 7 was confirmed by an X-ray analysis.Direct and benzophenone-sensitized photolyses of azoalkane 5 gave the tricycloalkane 13, while in the thermolysis also the pyrazole 12 was formed.Direct and benzophenone-sensitized photolyses of azoalkane 4 yielded bicyclohept-5-en-2-one (1), tricyclo2,7>heptan-3-one (2), and bicyclohept-3-en-6-one (3).Thermolysis gave only the bicyclic ketones 1 and 3.It is postulated that the photolysis and thermolysis of azoalkane 4 first lead to diazenyl diradicals 19a, b, which are differentiated in their chemical behavior on account of spin state multiplicities (singlet versus triplet) and electronic configurations (D?,? versus D?,?).Formation of the oxadi-?-methane-type 1,3-diradical 20 by denitrogenation involving double C-N cleavage represents a minor product channel.
