Recent advances towards azobenzene-based light-driven real-time information-transmitting materials

• Jaume García-Amorós and
• Dolores Velasco

Beilstein J. Org. Chem. 2012, 8, 1003–1017, doi:10.3762/bjoc.8.113

• devices. Many different organic photochromic molecules are known in photochemistry, such as azobenzenes, stilbenes, spiropyranes, fulgides, diarylethenes and chromenes among many others (Figure 1) [16]. The photochromic processes that take place when such compounds are illuminated can be divided in three

Synthesis of axially chiral oxazoline–carbene ligands with an N-naphthyl framework and a study of their coordination with AuCl·SMe₂

• Feijun Wang,
• Shengke Li,
• Mingliang Qu,
• Mei-Xin Zhao,
• Lian-Jun Liu and
• Min Shi

Beilstein J. Org. Chem. 2012, 8, 726–731, doi:10.3762/bjoc.8.81

• diaminocarbene) gold(I) complexes 3 derived from 3,3′-substituted 1,1′-binaphthalenyl-2,2′-diamine, and their application in the dynamic kinetic asymmetric transformation of propargyl esters, giving the corresponding substituted chromenes in up to 99% ee [12]. Our group also developed a new family of axially

A review of new developments in the Friedel–Crafts alkylation – From green chemistry to asymmetric catalysis

• Magnus Rueping and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2010, 6, No. 6, doi:10.3762/bjoc.6.6

• -carbon atoms of allenylidene-Ru 92 complex were attacked giving rise to the corresponding chromenes and 1-substituted 1H-naphtho[2,1-b]pyrans 93, respectively, in moderate to excellent yields (Scheme 35). Electron-withdrawing as well as electron-donating functional groups were tolerated on the phenol

• ) Propargylation of arenes with stoichiometric amounts of the Ru-allenylidene complex 86. (B) First catalytic propargylation of (hetero)arenes using a cationic Ru-complex. Diruthenium-catalyzed formation of chromenes and 1H-naphtho[2,1-b]pyrans. Rhenium(V)-catalyzed FC propargylations as a first step in the total

Synthesis of novel photochromic pyrans via palladium- mediated reactions

• Christoph Böttcher,
• Gehad Zeyat,
• Saleh A. Ahmed,
• Elisabeth Irran,
• Thorben Cordes,
• Cord Elsner,
• Wolfgang Zinth and
• Karola Rueck-Braun

Beilstein J. Org. Chem. 2009, 5, No. 25, doi:10.3762/bjoc.5.25

• was investigated by time-resolved absorption spectroscopy in the picosecond time domain. Keywords: benzopyrans; chromenes; naphthopyrans; palladium-mediated coupling reactions; photochromism; Introduction Interest in photoswitchable chromophores for the material and life sciences has increased

• (closed forms), also referred to as chromenes, leads to the formation of interconverting photoisomers of the open merocyanine-type (quinoidal, zwitterionic and hybrid forms and their stereoisomers), depending upon the substitution pattern of the parent pyrans and the conditions employed (Scheme 1

• . The transient was recorded at 470 nm (black) and is shown together with a single-exponential fit (red) yielding a decay time of 12 μs. Photochromism of 2H-chromenes. Synthesis of functionalized pyrans from 2-bromo-3H-naphtho[2,1-b]pyrans and 3-bromo-2H-1-benzopyrans by palladium-mediated