Chien-Tien Chen

Enantioselective Aerobic Oxidation of α-Hydroxy-Ketones Catalyzed by Oxidovanadium(V) Methoxides Bearing Chiral, N-Salicylidene-tert-butylglycinates

Chiral oxidovanadium(V) methoxides prepared from 3,5-disubstituted-N-salicylidene-l-tert-butylglycines and vanadyl sulfate in air-saturated MeOH serve as highly enantioselective catalysts for asymmetric aerobic oxidations and kinetic resolution of alkyl, aryl, and heteroaryl α-hydroxy-ketones with differed α-substituents at ambient temperature in toluene or TBME (tert-butyl methyl ether). The best scenarios involve the use of complexes which bear the tridendate templates derived from 3,5-diphenyl- or 3-o-biphenyl-5-nitro-salicyaldehyde. The kinetic resolution selectivities of the aerobic oxidation process are in the range of 12 to >1000 based on the selectivity factors (k(rel)).

Diastereoselective, synergistic dual-mode optical switch with integrated chirochromic helicene and photochromic bis-azobenzene moieties.

An unprecedented dual-mode optical switch by combining helicene and bis-azobenzene moieties in proximity allows for cooperative, highly diastereoselective chirochromic (92/8 to 3/97) and photochromic (>99/<1 to 19/81) switchings both in solution and in nematic LC with tunable pitches and handedness by permutation of four different metastable states.