Dephosphinylative [4 + 2] Benzannulation of Phosphinyl Ynamines: Application to the Modular Synthesis of Polycyclic Aromatic Amines

Abstract

A series of 9-amino-10-halophenanthrenes were synthesized through a one-pot process, including dephosphinylative Sonogashira–Hagihara coupling of 2-bromobiphenyls with air-stable phosphinyl ynamines, followed by halonium-promoted [4 + 2] benzannulation of the resulting 2-(aminoethynyl)­biphenyls. Nonsubstituted and methyl-substituted 2-bromobiphenyls rapidly underwent the Sonogashira–Hagihara aminoethynylation and the halogenative Friedel–Crafts benzannulation to provide the corresponding amino­(halo)­phenanthrenes in high yields, while electron-sufficient and -deficient substrates did slowly undergo the former and the latter to result in low yields, respectively. This protocol worked well for the syntheses of highly π-extended aminophenanthrenes and aminobenzonaphthothiophenes with different optical properties. Further application of this approach between 2,2″- and 2′,5′-dibromo-p-terphenyls with phosphinyl ynamines led to the regioselective formation of 6,13-diamino-5,12-dihalo- and 5,12-diamino-6,13-dihalo-dibenz­[a,h]­anthracenes via dual aminoethynylation and [4 + 2] benzannulation. The obtained analogues showed different ultraviolet–visible absorption and photoluminescence spectra with different emission quantum yields in CH2Cl2 solution and the powder state.

Enforcing Metal–Arene Interactions in Bulky p-Terphenyl Bis(anilide) Complexes of Group 2 Metals (Be–Ba): Potential Precursors for Low-Oxidation-State Alkaline Earth Metal Systems

“…Melting points were determined in sealed glass capillaries under dinitrogen and are uncorrected. The reagents 2,2′-dibromo- p -terphenyl, (TCHP)­NH 2 (2,4,6-tricyclohexyl aniline), Dip TerphH 2 , Mg­{CH 2 (SiMe 3 ) 2 } 2 , BePh 2 , and M­{N­(SiMe 3 ) 2 } 2 (M = Ca, Sr, Ba) were prepared according to literature procedures. All other reagents were used as received.…”

Chemodivergent Synthesis of Polycyclic Aromatic Diarylamines and Carbazoles by Thermal/Photochemical Process-Controlled Dephosphinylative Functionalizations of Amino(phosphinyl)arenes

“…Subsequently, an intramolecular cyclization with HNTf 2 led to the formation of phenanthrene PAA-β which had the Ph 2 N group at the βposition of the reaction site (step 2). 16 However, because the position of the amino group often plays a pivotal role in the physicochemical and material properties of functionalized PAAs, 17 we aimed to achieve a comprehensive regiodivergent synthesis of the regioisomer PAA-α. With the aim of achieving regioselective synthesis of 4-and 5-functionalized 1,2,3triazoles, we have successfully developed a process-controlled regiodivergent copper-catalyzed azide−alkyne cycloaddition (CuAAC) using a Ph 2 P(O)-stabilized alkyne (Scheme 1c).…”

“…In the first step, we achieved the dephosphinylative Sonogashira–Hagihara coupling of Ph 2 P­(O)-stabilized ynamine 1 with 2-aryl-1-bromobenzene 2 (X = Br in Scheme b) to form 2-(diphenylaminoethynyl)­biphenyl A (step 1). Subsequently, an intramolecular cyclization with HNTf 2 led to the formation of phenanthrene PAA-β which had the Ph 2 N group at the β-position of the reaction site (step 2) . However, because the position of the amino group often plays a pivotal role in the physicochemical and material properties of functionalized PAAs, we aimed to achieve a comprehensive regiodivergent synthesis of the regioisomer PAA-α .…”