Triple Benzannulation of Naphthalene via a 1,3,6-Naphthotriyne Synthetic Equivalent. Synthesis of Dibenz[a,c]anthracene

Abstract

A new synthesis of dibenzo[a,c]anthracene (4) is described that features the generation, from tetrabromo-bis-triflate 1 and phenyllithium, of a 1,3,6-naphthotriyne (2) synthetic equivalent that is trapped with 3 equiv of furan to form Diels-Alder tris-adduct 3. A subsequent two-step deoxygenation of 3 represents the first synthesis of dibenz[a,c]anthracene (4) that involves a tandem aryne Diels-Alder cycloaddition-deoxygenation strategy.

Recent advances in the syntheses of anthracene derivatives

“…In 2015, Gribble et al published a new method to synthesize dibenzo[ a , c ]anthracene ( 158 ) based on a triple benzannulation of naphthalene derivative 153 via a 1,3,6-naphthotriyne synthetic equivalent 155 ( Scheme 35 ) [ 69 ]. First, reaction of brominated naphthalene 153 with PhLi yielded compound 154 , which collapsed to naphthotriyne 155 at elevated temperatures.…”

“…Sequential addition of furan generated the trisadduct 156 . Then, dibenz[ a,c ]anthracene 158 was obtained in good yield (86%) in two steps by hydrogenation of 156 and further dehydration of 157 under reflux with concentrated HCl [ 69 ].…”

Synthesis of Phenacene–Helicene Hybrids by Directed Remote Metalation

“…Apart from the general methods reported for the preparation of PAHs, , representative examples of the recent approaches include cross-couplings followed by metal-catalyzed intramolecular cyclizations, − C–H activation, , oxidative alkene arylation of o -aryl styrenes, , photochemical cyclizations, − directional synthesis using transient directing groups, π-annulation reactions, APEX (annulative π-extension) reactions, from cycloaddition reactions of aryne precursors, − alkyne [2 + 2 + 2] cycloisomerizations, − and Diels–Alder reactions , among other protocols. − …”

Cascade Multiple Diels–Alder Reactions of Styrene Derivatives with Maleimide or Maleic Anhydride

“…Although multiple Diels–Alder reactions could offer an effective approach to polycyclic compounds with six-membered rings, currently there have been relatively few reports of multiple Diels–Alder reactions. Several examples of triple Diels–Alder reactions exist in addition to the above the Wagner-Jauregg reaction. , …”