The enantioselective synthesis of fully benzenoid single and double carbo[6]helicenes has been achieved via the gold-catalyzed intramolecular hydroarylation. The single crystal of the racemic double carbo[6]helicene consists of unique layer structures like timbers with halving joints in the woodworking. Furthermore, the double carbo[6]helicenes exhibited relatively large CPL activities among chiral small organic molecules.

The cationic gold(I)/(R)‐xyl‐binap complex was shown to catalyze the atroposelective intramolecular hydroarylation of alkynones to produce enantioenriched axially chiral all‐benzenoid biaryls, 4‐aryl‐2‐naphthol derivatives, with up to 67 % ee. The reaction of a racemic alkynone in the presence of the same gold(I) catalyst also afforded the corresponding axially chiral all‐benzenoid biaryl in excellent yield with 70 % ee.

It has been established that a cationic gold(I)/(R)‐H8‐binap complex catalyzes the enantioselective intramolecular [4+2] annulation of benzene‐linked ene‐yne‐carbonyls via benzopyrylium‐type intermediates at room temperature to give chiral tricyclic compounds, bearing two stereogenic centers, as single diastereomers with moderate ee values. Interestingly, the reactions of sterically demanding naphthalene‐linked ene‐yne‐carbonyls with the same gold(I) catalyst gave not only [4+2] annulation products but also [3+2] annulation products as minor products with good ee values.

The enantioselective synthesis of fully benzenoid single and double carbo[6]helicenes has been achieved via the gold‐catalyzed intramolecular hydroarylation. The single crystal of the racemic double carbo[6]helicene consists of unique layer structures like timbers with halving joints in the woodworking. Furthermore, the double carbo[6]helicenes exhibited relatively large CPL activities among chiral small organic molecules on page 5434 ff.