74503-34-7Relevant academic research and scientific papers
Mechanism of the Cyclopropane "Walk" Rearrangement: Syntheses and Properties of Diazoalkane Adducts of 1,3-Cyclobutadiene
Klaerner, Frank-Gerrit,Glock, Volker,Figge, Helga
, p. 794 - 812 (2007/10/02)
The synthesis and the thermal and photochemical behaviour of the specifically deuterated 2-diazopropane- and 2-diazo-1-methoxypropane adducts of 1,3-cyclobutadiene -1a, -1b, and -1c are reported.The elimination of N2 in -1a photochemically as well as thermally induced leads to a 1:1 mixture of the regioisomeric bicyclopentenes -3a and -3a or cyclopentadienes -12a and -12a formed as secondary products.Photolysis of the diastereomeric adducts -1b and -1c reveals that after extrusion of N2 each ring closure reaction between C-5 and C-1 or C-5 and C-3 gives the corresponding bicyclopentene system stereospecifically with retention at C-5.Diradicals -2b and -2c are postulated to be the transition states of the cyclisation reactions.The observation that the "walk" rearrangement in the bicyclopentene system proceeds with inversion at C-5 rules out the participation of a diradical of type 2 in this process.
Heats of Hydrogenation, II. Heats of Hydrogenation of Bicyclopent-2-ene, an Antiaromatic System
Roth, Wolfgang R.,Klaerner, Frank-Gerrit,Lennartz, Hans-Werner
, p. 1818 - 1829 (2007/10/02)
The heat of hydrogenation of the olefinic double bond in bicyclopent-2-ene (2) and in the 5,5-dimethyl derivative 22 has been determined (42.5 and 42.0 kcal mol-1).By comparison with the heat of hydrogenation of the double bond in bicyclohex-2-ene (10) and bicyclohept-6-ene (9) an antiaromatic destabilisation of 10 kcal mol-1 is demonstrated.The antiaromaticity of 2 is also manifested in its high dienophilic reactivity.The rate of the reaction of 2 with 1,3-cyclopentadiene (6) is enhanced by a factor of 4.5 * 104 compared to the analogous reaction of bicyclooct-7-ene (8).
