Herstellung und Reaktionen von 2,5-Diphenyl-6-oxo-1,3,4-oxadiazin

The Most Stable and Fully Characterized Functionalized Heptacene

“…The 2,5-diaryl-6-oxo-1,3,4-oxadiazine-6-one 3 [16] is an electron-deficient diene that undergoes an inverse-electrondemand Diels-Alder reaction twice with benzyne to give the resulting anthracene derivative 4.…”

Cyclic Alkyne Approach to Heteroatom-Containing Polycyclic Aromatic Hydrocarbon Scaffolds

“…This would enable access to ar ange of heterocyclic PA H scaffolds,w ith the possibility of accessing four quadrants of differentiation. [46] Thes uccess of this approach would hinge on uncovering ameans to allow for the controlled generation and trapping of fragments 8 and 10 to ultimately deliver products 7 through the cascade of events suggested in Figure 2b.Key precedent stems from pioneering studies by Steglich in 1977, [47] which demonstrated the double addition of benzyne into oxadiazinones,i na ddition to the syntheses of conjugated materials by Nuckolls [48] and Wudl. Heterocyclic strained intermediates (e.g.…”

“…We hypothesized that the intermediate benzopyrone was more reactive than the oxadiazinone, preventing isolation or second addition of ad ifferent aryne. [46][47][48] However,w hen a1 :2 ratio of 11 and 12 was utilized, the desired pyrones 13,arising from asingle DA/rDA [51] Thus,w eu sed ah eterocyclic alkyne derived from commercially available silyl triflate 11 (prepared in 3s teps from 4-methoxypyridine).…”

Cyclic Alkyne Approach to Heteroatom-Containing Polycyclic Aromatic Hydrocarbon Scaffolds

“…Oxadiazinones (diazapyrones) are easily prepared from simple precursors [45] and are known to readily undergo one or more Diels-Alder (DA) cycloaddition/ retro-Diels-Alder (rDA) cycloaddition reactions (with sequential expulsion of N 2 and CO 2 ). [46] Thes uccess of this approach would hinge on uncovering ameans to allow for the controlled generation and trapping of fragments 8 and 10 to ultimately deliver products 7 through the cascade of events suggested in Figure 2b.Key precedent stems from pioneering studies by Steglich in 1977, [47] which demonstrated the double addition of benzyne into oxadiazinones,i na ddition to the syntheses of conjugated materials by Nuckolls [48] and Wudl. [49] However,anotable limitation in all cases is the inability to introduce two different strained alkynes,i nstead delivering symmetric products with respect to building blocks A and B.…”

“…[13] Tw ok ey results ( Figure 3) illustrate the ability to modulate the product distribution through alteration of the reaction stoichiometry.Whensilyl triflate 11 was employed in excess,t he major products were adducts 14,c onsistent with the results previously seen in aryne/oxadiazinone reactions. [46][47][48] However,w hen a1 :2 ratio of 11 and 12 was utilized, the desired pyrones 13,arising from asingle DA/rDA…”