Mild arylboronic acid catalyzed selective [4 + 3] cycloadditions: access to cyclohepta[b]benzofurans and cyclohepta[b]indoles.

The first example of arylboronic acid catalyzed [4 + 3] cycloaddition reaction is reported. 3,5-Bis-(trifluoromethyl) phenylboronic acid is shown to be the best catalyst in this reaction. The method has also enabled the preparation of cyclohepta[b]benzofurans and cyclohepta[b]indoles in excellent yields.

Chiral phosphoric acid catalyzed highly enantioselective desymmetrization of 2-substituted and 2,2-disubstituted 1,3-diols via oxidative cleavage of benzylidene acetals.

A highly enantioselective catalytic protocol for the desymmetrization of a wide variety of 2-substituted and 2,2-disubstituted 1,3-diols is reported. This reaction proceeds through the formation of an "ortho ester" intermediate via oxidation of 1,3-diol benzylidene acetal by dimethyldioxirane (DMDO) and the subsequent proton transfer catalyzed by chiral phosphoric acid (CPA). The mechanism and origins of enantioselectivity of this reaction are identified using DFT calculations. The oxidation by DMDO is rate-determining, and the phosphoric acid significantly accelerates the proton transfer; the attractive interactions between the benzylidene part of the substrate and the 2,4,6-triisopropyl group of CPA are the key to high enantioselectivity.

Linear heterocyclic aromatic fluorescence compounds having various donor-acceptor spacers prepared by the combination of carbon-carbon bond and carbon-nitrogen bond cross-coupling reactions.

A family of novel linear 1,10-phenanthroline-based (A-D-A-D-A) and oligothiophene-based (A-D-D-D-(D)-A) heterocyclic aromatic fluorescence compounds having N-containing imidazole and pyridine tails with effective π-conjugated systems, prepared by the combination of carbon-carbon (C-C) bond and carbon-nitrogen (C-N) bond cross-coupling reactions, is described. They have molecular lengths of more than 2.30 nm in the cases of 4, 6, 9, and 26, various D-A spacers, and certain N-coordination sites (phen, imidazole, and pyridine). X-ray single-crystal structures of 13 compounds reveal a variety of trans and cis configurations with different dihedral angles between adjacent aromatic heterocycles. Synthetic, computational, and spectral studies have been made to reveal the differences between cross-coupling approaches on the C-C bond and C-N bond formation as well as band gaps and energy levels and optical and electrochemical properties for related compounds. The influences of introducing a ß-methyl group to the thiophene ring on reaction activity, solubility, and conformation of related compounds have also been discussed.

A catalytic enantioselective approach to tetrol bearing vicinal all-carbon quaternary stereogenic centers.

The first highly enantioselective catalytic protocol for selective manipulation of tetrol benzylidene acetals through chiral phosphoric acid mediated oxidative desymmetrization is reported. This efficient approach provides a general access to vicinal all-carbon quaternary stereogenic center structural motifs, as well as structures containing vicinal tertiary and quaternary stereocenters enantioselectively. The synthetic utility has been furthermore demonstrated by transformations and gram-scale processes.