TfOH-promoted Classical Nazarov-type Cyclization of Benzofulvenes: Synthesis of Polycyclic 5H,10′H-spiro[benzo[k]phenanthridine-5,6′-dibenzopentalenes]

Abstract

The reaction of o-benzofulvene with TfOH leads to intramolecular cyclization through novel C–C and C–N bond formation, resulting in the formation of 5H,10′H-spiro­[benzo­[k]­phenanthridine-5,6′-dibenzopentalene]. This protocol provides a new molecular framework with reasonable to excellent yields and tolerates various electron-withdrawing/donating substituents. This method yields diastereoselectivity of up to >20:1. Furthermore, it is free of bases, oxidants, and metals and proceeds under mild reaction conditions, which are favorable for synthetic organic chemistry.

One-Pot Double Intramolecular Cyclization Approach to Tetralin-Based Cis-Fused Tetracyclic Compounds

“…13 C{ 1 H} NMR (100 MHz, CDCl 3 ): δ 138. 2,137.2,136.7,135.0,133.2,130.6,129.8,129.3,128.9,128.5,126.3,125.6,44.0,33.4,31.5,27.5,27.2,20.9,20.2. Anal.…”

“…Recent years have witnessed numerous such reactions for the rapid construction of diverse polycyclic carbo-and heterocycles. 2 Nevertheless, development of new one-pot double intramolecular cyclization strategies, especially which are based on the use of non-transition metal catalysts and show high atom economy and stereoselectivity, remains challenging yet highly desirable.…”

Cu−NHC Complex for Chan‐Evans‐Lam Cross‐Coupling Reactions of N‐Heterocyclic Compounds and Arylboronic Acids

“…Copper(II) N-heterocyclic carbene (NHC) complexes have been attracting attention due to their strong σ-donor properties. [7] The carbon-metal coordination mode has a significant impact on the electronic structure of these copper(II) complexes. These CuÀ NHC systems show remarkably broad applications toward click chemistry, conjugate addition, hydrosilyation reactions, reduction processes, and CÀ X cross-coupling reactions.…”

Copper complexes for the chemoselective N-arylation of arylamines and sulfanilamides via Chan–Evans–Lam cross-coupling

“…Over the past few decades, transition metal-catalyzed crosscoupling reactions have become indispensable methodologies to achieve the single-step preparation of structurally valuable sp, sp 2 , and sp 3 -carbon functionalized products. 1,2 The C-N cross-coupled or N-arylated architecture is prevalent in sulfa drugs, natural products, and pharmaceutical designs 3,4 such as sulfadiazine, 5 sulfacytine, 6 sulfisoxazole, 7 sulfamethizole, 8 sulfamethoxazole, 9 sulfamoxole, 10 sulfadoxine, 11 sulfalene, 12 furosemide, 13 sulfasalazine (Azulfidine), 14 mafenide, 15 and sulfacetamide 16 (Fig. 1).…”