Synthesis of N-acetyl diazocine derivatives via cross-coupling reaction

• Thomas Brandt,
• Pascal Lentes,
• Jeremy Rudtke,
• Michael Hösgen,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2025, 21, 490–499, doi:10.3762/bjoc.21.36

• Abstract Diazocines are photoswitches derived from azobenzenes by bridging the two phenyl rings in ortho position with a CH2CH2 group forming an eight membered (diazocine) ring. Diazocine is superior to most azobenzenes in almost all photophysical properties (switching efficiency, quantum yield

• -substituted diazocines were prepared via Stille, Suzuki, and Buchwald–Hartwig reactions. X-ray structures are presented for derivatives 1, 2 and 7. Keywords: cross-coupling; diazocine; N-acetyl diazocine; photoisomerization; photoswitch; thermal relaxation; Introduction Diazocines are frequently used

• photoswitches with superior photophysical properties. The parent ethylene-bridged diazocine shows excellent switching photoconversion between the Z and the E configurations (Γ(Z → E)385nm = 92% and Γ(E → Z)520nm > 99% in n-hexane) due to well-separated n–π*-transitions in the visible part of the electromagnetic

Substituted nitrogen-bridged diazocines

• Pascal Lentes,
• Jeremy Rudtke,
• Thomas Griebenow and
• Rainer Herges

Beilstein J. Org. Chem. 2021, 17, 1503–1508, doi:10.3762/bjoc.17.107

• makes them promising candidates for applications in photopharmacology. The halogen substituents allow further functionalization via cross-coupling reactions. Keywords: bridged azobenzene; diazocine; photopharmacology; photoswitch; triazocine; visible light switch; water-soluble switch; Introduction

• Diazocines (bridged azobenzenes) are frequently used photoswitches with outstanding photophysical properties. Parent diazocine (CH2–CH2-bridged) exhibits well-separated n–π* transitions, which allow excellent photoconversion between the Z and E configurations ((Z→E)385 nm = 92%, (E→Z)525 nm > 99% in n-hexane

• Z→E switching efficiencies in water are additional important criteria for applications in biological environments [14]. Our previously published NAc-bridged diazocine 10c (Scheme 1, Table 1) exhibits both properties [15]. This is in stark contrast to the CH2–CH2 and S–CH2-bridged diazocines and the

Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• self-absorption and a wider stokes shift [17]. Further, the steric hindrance and highly rigidity could reduce non-radiative transition and restrict the internal rotation [18]. More importantly, in the TB structure, its bridged methylene groups of the diazocine chiral nitrogen atoms prevent the

• CPL-active co-gel can be controlled effectively (Scheme 1). Results and Discussion The synthetic routes of rac-TBPP are outlined in Supporting Information File 1, Scheme S1. Firstly, 2,8-dibromo-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine was synthesized according to the reported procedure [22

• ]. Then, by Suzuki coupling reaction between 2,8-dibromo-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine and 4-vinylpyridine, rac-TBPP was successfully obtained in 51.8% yield. Detailed experiments and characterization were described in Supporting Information File 1 (Figures S1–S3). Firstly, rac-TBPP was

Diazocine-functionalized TATA platforms

• Roland Löw,
• Talina Rusch,
• Fynn Röhricht,
• Olaf Magnussen and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 1485–1490, doi:10.3762/bjoc.15.150

• gold. To investigate this mechanism further and to examine scope and limitation of the “spin-switch catalysis” we now prepared analogous diazocine systems. Diazocines, in contrast to azobenzenes, are stable in the cis-configuration. Upon irradiation with light of 405 nm the cis-configuration isomerizes

• ordered monolayers on Au(111) surfaces. Keywords: cis–trans isomerization; diazocine; molecular switch; photochrome; self-assembled monolayers; TATA platform; Introduction Catalysts increase chemical reaction rates by lowering the activation energies and thus create more favorable reaction pathways [1

• investigate if the reverse isomerization process from the trans to the cis-configuration would also be accelerated, and to further scrutinize the coupling effects, we prepared analogous diazocine systems. Diazocines are bridged azobenzenes [21]. Imposed by the ring strain of the central eight-membered ring

Synthesis of functionalized diazocines for application as building blocks in photo- and mechanoresponsive materials

• Widukind Moormann,
• Daniel Langbehn and
• Rainer Herges

Beilstein J. Org. Chem. 2019, 15, 727–732, doi:10.3762/bjoc.15.68

• molecular switches in photo and mechanoresponsive macromolecules and other smart materials. Keywords: bridged azobenzene; diazocine; mechanophor; oxidative C–C coupling; photochrome; reductive azo cyclization; Introduction The field of photoresponsive materials is of growing interest [1][2][3]. Several

• , diazocines are stable over several thousand switching cycles under air [19][24][26][27]. Notwithstanding their excellent properties, to date only 3,3’- and 4,4’- functionalized diazocine 2 and 3 have been implemented in polymers [19] and proteins [28]. Unfortunately, similar to azobenzenes, aminosubstitution

• at the phenyl rings reduces switching efficiency [29]. In contrast to the parent system, separation of absorption bands of the cis and trans isomer in 2 and 3 is poor. Upon irradiation of the corresponding cis-configured compounds at 385 nm only 30% of the trans isomer of 3,3’-diazocine 2 and 25% of

Synthesis of mono-functionalized S-diazocines via intramolecular Baeyer–Mills reactions

• Miriam Schehr,
• Daniel Hugenbusch,
• Tobias Moje,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2018, 14, 2799–2804, doi:10.3762/bjoc.14.257

• receptor. Hence, it should be possible to administer the stabile inactive compound and switch it on at the site of illness with visible light. To date only a limited number of diazocine derivatives have been published of which most are symmetrically functionalized. Using the Baeyer–Mills reaction for the

• synthesis of diazocines opens a novel and convenient access to unsymmetrically substituted diazocines. Keywords: Baeyer–Mills reaction; bridged azobenzene; diazocine; reductive azo condensation; unsymmetrically functionalized S-diazocines; Introduction Photopharmacology is a promising, rapidly evolving

• the synthesis of a diazocine where the –CH2–CH2– bridge is replaced by a –CH2–S– bridge (S-diazocine) using an ultrasound-supported reductive azocoupling with lead [17]. In this reaction a small amount of S-diazocine is directly formed and a larger fraction of the azoxy compound is obtained, which can

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• -pyrido-diazocine 46 with an excellent yield of 94% (Scheme 18) [56]. The presence of the two sulfonamide substituents on the pyridyl ring might decrease the basicity of the nitrogen atom thus allowing the metathesis to proceed. Steric hindrance due to the C2 substitution may also prevent the pyridine

• . Enyne ring-closing metathesis. Synthesis of (R)-(+)-muscopyridine using a RCM strategy. Synthesis of a tris-pyrrole macrocycle. Synthesis of a bicyclic imidazole. RCM using Schrock’s catalyst 44. Synthesis of 1,6-pyrido-diazocine 46 by using a RCM. Synthesis of fused pyrimido-azepines through RCM. RCM

Self-assembly of heteroleptic dinuclear metallosupramolecular kites from multivalent ligands via social self-sorting

• Christian Benkhäuser and
• Arne Lützen

Beilstein J. Org. Chem. 2015, 11, 693–700, doi:10.3762/bjoc.11.79

• -{(trimethylsilyl)ethynyl}pyridine (7) [27], 5-{(trimethylsilyl)ethynyl}-2,2'-bipyridine (10) [28], and 5-ethynyl-2,2'-bipyridine (11) [28] were prepared according to literature known procedures. (rac)-6H,16H-5,15-Methanodi-1N,10N,11N,20N-phenanthro[5’,6’-b,5’’,6’’-f][1,5]diazocine ((rac)-1): 5-Aminophenanthroline

Amino-substituted diazocines as pincer-type photochromic switches

• Hanno Sell,
• Christian Näther and
• Rainer Herges

Beilstein J. Org. Chem. 2013, 9, 1–7, doi:10.3762/bjoc.9.1

• realized in the dihydrodibenzo diazocine framework. We present the synthesis and properties of 3,3’-amino- and 3,3’-acetamido substituted diazocines. Upon irradiation with light of 405 and 530 nm they isomerize from the cis to the trans configuration and back, and thereby perform a pincer-like motion. In

• the thermodynamically more stable cis isomer the lone pairs of the amino nitrogen atoms point towards each other, and in the trans form they point in opposite directions. The distance between the amino nitrogen atoms changes between 8 Å (cis) and 11 Å (trans isomer). Keywords: azobenzene; diazocine

• ]diazocine (1), has been known for more than a hundred years [5]. However, only recently we discovered that the photophysical properties of 1 (quantum yields, photostationary states) are superior to those of parent azobenzene, and most of its derivatives [6][7][8]. In contrast to azobenzene, diazocine 1 is