The properties of nanographenes can be tuned by changing their shapes, therefore the development of new methods suitable for the synthesis of various nanographenes is highly desirable. Described herein is an intramolecular InCl /AgNTf -catalyzed regioselective domino benzannulation reaction of buta-1,3-diynes to build irregular nanographenes. Different nanographene compounds were easily obtained in moderate to high yields through careful design of the precursor compounds. This new domino reaction was successfully applied to a fourfold alkyne benzannulation of dimethoxy-1,1'-binaphthalene derivatives to arrive at novel chiral butterfly ligand precursors. The regioselectivity of the benzannulation reaction was unambiguously confirmed by X-ray crystallography. Moreover, this new method enables us to synthesize different nanographene isomers and study their optical properties as a function of shape.

The synthesis of pyreno­[a]­pyrene-based helicene hybrids was achieved in good yield via a four-fold alkyne benzannulation reaction that was promoted by Brønsted acid. The molecules are configurationally locked, allowing the enantiomers to be separated using chiral HPLC so that their photophysical and chiroptical properties, including circular dichroism and circularly polarized luminescence, could be studied.

Terminal or subterminal olefins can be selectively formed from alkyl electrophiles via bio-inspired vitamin B12 photocatalysis.

General Methods. All reactions were performed in flame-dried glassware under a N 2 atmosphere. Solvents were degassed and dried by standard methods before use. Purification of the crude products was carried out by column chromatography using silica gel. Analytical TLC was performed on a silica gel GF 254 plate. The TLC plates were visualized under ultraviolet (UV, 254 nm) light or by staining with PMA or CAM. NMR spectra were recorded on a 400 or 500 MHz NMR spectrometer in CDCl 3. Proton chemical shifts are expressed in parts per million (ppm, δ scale) and are referenced to residual protium in the NMR solvent (CDCl 3 , δ 7.26). Data for 1 H NMR are reported as follows: chemical shift, multiplicity (s=singlet, d=doublet, t=triplet, q=quartet, m= multiplet, br=broad), coupling constant (J) in Hertz, and integration. Carbon chemical shifts are expressed in parts per million (ppm, δ scale) and are referenced to the carbon resonance of the NMR solvent (CDCl 3 , δ 77.16). Infrared (IR) spectra were recorded on an ATR/FTIR spectrometer as a thin film on a composite of zinc selenide and diamond crystal and only major functional group peaks are reported in cm-1. High-resolution mass spectra (HRMS) were obtained on a high-resolution Q-TOF mass spectrometer (ionization mode: ESI). Commercially available reagents and solvents were used without further purification. Diynones 1a-1f 1,2 and 1g-1h, 3 as well as diene 2d 4 were synthesized according to reported procedures. S3 General Procedure for Diels-Alder reaction of diynones: To a solution of diynone 1 (1.0 equiv.) and diene 2 (5.0 equiv.) in dichloromethane (ca. 0.05-0.15 M) was added dimethylaluminum chloride (1.0 M in hexanes, 1.0 equiv.) slowly over 10 minutes. The reaction mixture was stirred at room temperature for 1-5 h, quenched with dilute aq. NaHCO 3 , dried over anhydrous MgSO 4 and filtered. The solvent was removed in vacuo and the crude product was purified by column chromatography (silica gel).

A highly regioselective synthesis of 2,3-disubstituted chromen-4-one derivatives is accomplished from readily available internal alkynes and 2-methoxybenzoyl chlorides. The reaction proceeds via a domino intermolecular Friedel-Crafts acylation/intramolecular vinyl carbocation trapping (or oxa-Michael addition)/demethylation reaction sequence. This Lewis acid promoted method features relatively mild reaction conditions to synthesize a variety of 2,3-disubstituted chromen-4-one derivatives in one pot with up to 93% yield. The chromen-2-one (coumarin) product was obtained when 2,6-dimethoxybenzoyl chloride was used as a starting material via an electrophilic aromatic substitution/rearrangement process.