A theoretical study on cycloaddition reactions between [c]-annelated heterocyclic five-membered dienes and acetylene

A Theoretical Study of Tricyclo[4.2.1.02,5]non‐2(5)‐ene, Tricyclo[4.2.2.02,5]dec‐2(5)‐ene and Related Pyramidalized Alkenes

“…[9] On the other hand, Roth and co-workers found a heat of hydrogenation of 44.9 kcal mol -1 for 5. [10] More recently, 5, 6, 10 and 11 were theoretically studied in connection with a DFT study on the cycloaddition reactions of cyclobutano[c]cyclopentadiene and cyclobutano[c]furan with ethylene and acetylene, [11] and Gilbert and co-workers have reported that treatment of bicyclo[2.2.1]hept-2-yne (norbornyne, 15) with 2,3-dihydropyran gave a mixture containing 16. [12] On the other hand, dehalogenation of dichloride 17 with tert-butyllithium followed by quenching with [D 1 ]methanol led to 19, probably through the intermediacy of 18, a benzo derivative Scheme 1.…”

Density functional theory study of the Diels–Alder reactivities of [b]‐annelated cyclic five‐membered dienes

“…[1][2][3][4] The dienes can be broadly classified as simple, substituted and masked dienes. The masked dienes, which have been extensively studied experimentally 5-7 and theoretically, [8][9][10][11][12] can be categorized into cumulated, ring-fused and cage-fused dienes. The Diels-Alder reactions of simple five-membered heterocyclic ring dienes and their annelated analogues with a range of dienophiles lead to impressive Diels-Alder adducts, [8][9][10][11][13][14][15][16] and some of them have interesting industrial and biological applications.…”

“…The masked dienes, which have been extensively studied experimentally 5-7 and theoretically, [8][9][10][11][12] can be categorized into cumulated, ring-fused and cage-fused dienes. The Diels-Alder reactions of simple five-membered heterocyclic ring dienes and their annelated analogues with a range of dienophiles lead to impressive Diels-Alder adducts, [8][9][10][11][13][14][15][16] and some of them have interesting industrial and biological applications. [1][2][3][17][18][19][20] The benzo-annelated five-membered rings have been the subjects of interest for several years and the experimental routes for both benzo [b]-and -[c]-annelated thiophenes and pyrroles have been known for some time, as these compounds are intermediates in the synthesis of biologically important species.…”

“…12a Theoretical studies play an important role in understanding of the relative stabilities, reactivity and thermodynamic stability of series of reactant pairs. 8,9,[13][14][15] Once a reliable computational method has been established, detailed calculations on a series of reactant pairs help in rationally designing feasible reaction pathways. Diels-Alder reactions of simple dienes and dienophiles have been studied extensively at various levels of theory, [13][14][15] but quantitative calculations on the masked dienes reaction profiles are limited.…”

“…13a We also have theoretically studied the Diels-Alder reactivities of [c]-annelated five-membered rings with both ethylene and acetylene as dienophiles. 8,9 The aim of the present study is to examine the reactivities of the cycloaddition reactions of cyclobutano [b]-, cyclobuteno [b]and benzo [b]-fused five-membered ring dienes with ethylene and acetylene as dienophiles. The present study addresses how the Diels-Alder reactivity alters as a function of the position of annelation and the type of ring on the five-membered ring dienes by comparison with our recent studies reported for [c]-annelated dienes.…”