Iron(III) bromide catalyzed bromination of 2-tert-butylpyrene and corresponding position-dependent aryl-functionalized pyrene derivatives

The present work probes the bromination mechanism of 2-tert-butylpyrene (1), which regioselectively affords mono-, di-, tri- and tetra-bromopyrenes, by theoretical calculation and detailed experimental methods. The bromine atom may be directed to the K-region (positions 5- and 9-) instead of the more reactive 6- and 8-positions in the presence of iron powder. In this process, FeBr₃ plays a significant role to release steric hindrance or lower the activation energy of the rearrangement. The intermediate bromopyrene derivatives were isolated and confirmed by ¹H NMR spectrometry, mass spectroscopy and elemental analysis. Further evidence on substitution position originated from a series of aryl substituted pyrene derivatives, which were obtained from the corresponding bromopyrenes on reaction with 4-methoxy-phenylboronic acid by a Suzuki–Miyaura cross-coupling reaction. All position-dependent aryl-functionalized pyrene derivatives are characterized by single X-ray diffraction, ¹H/¹³C NMR, FT-IR and MS, and offered straightforward evidence to support our conclusion. Furthermore, the photophysical properties of a series of compounds were confirmed by fluorescence and absorption, as well as by fluorescence lifetime measurements

Bis(2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl) carbonate

The title compound, C21H22O5, crystallizes with three mol­ecules in the asymmetric unit. In one mol­ecule, two methyl groups are disordered over two positions with a site occupation factor of 0.72 (2) for the major occupancy site. The benzene rings make dihedral angles of 35.3 (6), 29.7 (6) and 40.6 (7)° in the three molecules

2-(2,2-Dimethyl-2,3-dihydro-1-benzofuran-7-yl­oxy)acetic acid monohydrate

In the title compound, C12H14O4·H2O, the dihydro­benzo­furan ring adopts an envelope conformation with the substituted C atom 0.142 (1) Å out of the least-squares plane. In the crystal, the components are linked via inter­molecular Owater—H⋯O and O—H⋯Owater hydrogen-bonding inter­actions, forming a three-dimensional network

2-(2,2-Dimethyl-2,3-dihydro-1-benzofuran-7-yl­oxy)-N-(o-tol­yl)acetamide

In the title compound, C19H21NO3, the dihedral angle between the mean planes of the two benzene rings is 38.13 (12)°. The furan ring adopts an envelope-like conformation with the C atom bonded to the dimethyl groups displaced by 0.356 (2) Å from the plane through the other four atoms. In the crystal, mol­ecules are linked into inversion dimers by weak C—H⋯O inter­molecular inter­actions

2,2,7,7-Tetra­methyl-2,3,6,7-tetra­hydro­benzofuro[7,6-b]furan

The title compound, C14H18O2, was obtained as a by-product during the preparation of carbofuran phenol. The two dihydro­furan rings are in envelope conformations

Pheromonal predisposition to social parasitism in the honeybee Apis mellifera capensis

In honeybees, worker reproduction is mainly regulated by pheromones produced by the brood and the queen. The source of one of the queen pheromones influencing worker reproduction has been located in the mandibular glands. In nonlaying workers, this gland's profile is dominated by fatty acids that are incorporated into the food given to the brood and to nest mates. After queen loss and onset of reproductive activity, workers are able to synthesize different fatty acids, which are normally only produced by queens and that contribute to their reproductive success. Apis mellifera capensis workers have the ability to rapidly produce queen-like mandibular profiles that could represent an important factor in their ability to behave as facultative intraspecific social parasites. Indeed, A. m. capensis workers can take over reproduction from the host queens in colonies of other subspecies. Here, we show that in the presence of their own queen, the mandibular gland profile of A. m. capensis workers is dominated by the precursor of the major compound of the queen pheromone. This is a unique trait among honeybee workers and suggests that A. m. capensis workers are primed for reproduction and that this phenomenon represents a pheromonal predisposition to social parasitism. We identified geographical variation in the ratio of queen- to worker-specific compounds in the mandibular gland profile of A. m. capensis workers, which corresponds with the introgression with the neighboring subspecies A. m. scutellat