7164-08-1Relevant academic research and scientific papers
Thermal Decomposition of a Series of 1,2-Diazetines
Breton, Gary W.,Shugart, John H.
, p. 8643 - 8649 (2007/10/03)
A homologous series of tricyclic diazetines (6a-c), differing by the number of methylene groups in the saturated bridges of the fused carbon bicycles, was synthesized. The ΔH? of decomposition for each of the diazetines to afford N2 and the corresponding alkene was determined experimentally: 6a, 31.7; 6b, 39.3; 6c, 38.8 kcal/mol. The ground-state strain energy of each diazetine was estimated utilizing computationally obtained ΔHf's for each of the experimentally investigated diazetines as well as several other diazetines whose ΔH?'s had been previously reported in the literature. The sum of the ground-state strain energies and ΔH?'s of decomposition for all of the diazetines was nearly constant, with an average value of 59 kcal/mol, suggesting that all of the diazetines decompose via the same mechanism. Generally, the higher the ground-state strain energy of the diazetine, the less the ΔH? for decomposition. The decomposition transition states for 6a-c and 7 were modeled computationally at the RB3LYP/6-311+G(3df,2p)//UB3LYP/6-31+G(d,p) level. The agreement of the experimentally determined ΔH? values with transition-state energies obtained computationally supports the reaction mechanism originally proposed by Yamabe that the elimination process occurs by an unsymmetrical, yet concerted, transition state with strong biradical character.
(Z)- and (E)-1,2-Bis(phenylsulfonyl)ethylenes as Synthetic Equivalents to Acetylene as Dienophile
Lucchi, Ottorino De,Lucchini, Vittorio,Pasquato, Lucia,Modena, Giorgio
, p. 596 - 604 (2007/10/02)
A new method for introducing an ethylenic bridge via a cycloaddition reaction has been developed.It makes use of either (Z)- or (E)-1,2-bis(phenylsulfonyl)ethylene (5 or 6) as synthetic equivalents of acetylene.The high activation due to the two sulfonyl groups promotes cycloaddition even to very unreactive dienes.The removal of the two sulfonyl groups for the required formation of the carbon-carbon double bond is promoted by reduction with metal amalgams in high yields.These properties, associated with the stability of the reagents and the ease of performance of the reactions, make this method a very useful synthetic tool for the preparation of polycyclic dienes and a valid alternative to the commonly available reagents that largely depend upon oxidative methods.
