Synthesis of Regioselectively Functionalized Pyrenes via Transition-Metal-Catalyzed Electrocyclization

Abstract

Transition-metal-catalyzed electrocyclic rearrangement of 2,6-diethynyl-1,1¢-biphenyl precursors to form polysubstituted pyrenes is described. This method is useful for the preparation of pyrenes with uncommon substitution patterns, and selective integration of functional groups at the 1-, 2-, 3-, 5-, 7-and 9-positions is demonstrated.

Highly Regioselective Domino Benzannulation Reaction of Buta‐1,3‐diynes To Construct Irregular Nanographenes

“…[7b, 17] Therefore, we initiated this study by screening suitable catalytic conditions for the domino benzannulation reaction of electron-rich buta-1,3-diyne 1a as a model substrate with the results summarized in Table 1. Transition metals, such as In(III), [12b, 18] Au(I), [19] Au(III), [12b] and Pt(II), [12b, 20] have been successfully used in the Lewis acid-catalyzed benzannulation reaction of alkynes and these metals have provided a starting point for our study. Recently, we have shown that a wide scope of peropyrenes and teropyrenes could be synthesized through two-and four-fold alkyne benzannulations using InCl3 as a catalyst in toluene at high temperature.…”

Homogeneous Gold Catalysis for Regioselective Carbocyclization of Alkynyl Precursors

“…By elaborating Fürstner's approach, Davis's group demonstrated the AuCl catalyzed 6-endo-dig carbocyclization of 2,6bis-iodoalkynyl-biphenyl 3.7, where they observed an 1,2-iodo migration to obtain 5,9-diiodopyrene derivative 3.8 (Scheme 15, eq 1). [127] A heteroaromatic version comprising 6-endo-dig carbocyclization of 3-alkynyl-4-arylisoquinolines 3.9 leading to benzo[a]phenanthridines 3.10 was achieved by cationic [Ph 3 PAu(I)] + catalysis (Scheme 15, eq 2). [128] The exclusive 6endo-dig selectivity can be accredited to the attainment of aromatic stability in products 3.10.…”

Nanographene and Graphene Nanoribbon Synthesis via Alkyne Benzannulations

“…Alkyne benzannulations using Pt(II) catalysis has also become a popular method to arrive at various NGs [79,80,83,84,85]. For example, Liu and coworkers developed a four-step synthesis of chrysene 69 from cheap, commercially available starting materials with the key step involving a Pt(II)-catalyzed alkyne benzannulation of intermediate 68 (Scheme 15) [83].…”

“…Surprisingly, the synthesis of large NGs using Au-catalysis is rare but has been successfully employed for alkyne benzannulations to afford various small NGs, including chiral helicene-like compounds [104], pyrenes [71,72,84], and phenanthrenes [69,75,76].…”