Effective enantiomeric separations of erythro- and threo-8.O.4'-neolignans with different aromatic substitution pattern (1a-i, 2a-i) are achieved on the commercially available chiral stationary phase cellulose tris(3,5-dimethylphenylcarbamate) (Chiralcel OD). It is shown that the chiral recognition of the stationary phase is significantly dependent on the substitution pattern of the racemic com...

Efficient C-H functionalization requires selectivity for specific C-H bonds. Progress has been made for directed aromatic substitution reactions to achieve ortho and meta selectivity, but a general strategy for para-selective C-H functionalization has remained elusive. Herein we introduce a previously unappreciated concept that enables nearly complete para selectivity. We propose that radicals ...

Trialkylamine-mediated intramolecular cyclization of pent-4-enoyl chlorides was studied. Substitution with a tertiary alkyl group at the 2-position gave cyclopent-2-en-1-ones, while substitution with an aromatic group gave enol esters, which were formed by O-acylation of initially formed 3-chlorocyclopentanones with ketenes.