Chiral chelated lithium amides were designed and synthesized. Studies have been done to explore the use of these lithium amides or their corresponding amines for enantioselective reactions such as deprotonation of prochiral cyclic ketones, kinetic resolution of racemic 2-substituted cyclohexanones by deprotonation, regioselective deprotonation of optically active 3-keto steroids, alkylation of ...

The removal of 75% of the lipid from bacteriorhodopsin caused the following: (i) decreased efficiency and rate of deprotonation of the protonated Schiff base (as monitored by absorption of the M412 intermediate); (ii) increased efficiency of deprotonation of deionized samples; (iii) a decrease by 1 unit in the pH at which deprotonation ceases; (iv) increased intensity of Eu3+ emission in Eu3+-r...

Reduction of dixanthylidene with potassium or lithium resulted in formation of the antiaromatic dianion in high yield. Attempts to form the dianion by excited-state deprotonation of dixanthene with n-butyllithium/TMEDA resulted in formation of the tetraanion from deprotonation ortho to the oxygen. Orientation of the sp(3) hydrogens presumably allows preferential deprotonation of the xanthene ri...

Fragmentation of metastable anions of all deoxynucleosides and nucleosides constituting DNA and RNA has been studied experimentally and by computer simulations. The ions were formed through deprotonation in matrix assisted laser desorption/ionisation (MALDI). Clear difference in fragmentation patterns was obtained for nucleosides containing purine vs. pyrimidine bases. To elucidate the role of ...

Fragmentation of metastable anions of all deoxynucleosides and nucleosides constituting DNA and RNA has been studied experimentally and by computer simulations. The ions were formed through deprotonation in matrix assisted laser desorption/ionisation (MALDI). Clear difference in fragmentation patterns was obtained for nucleosides containing purine vs. pyrimidine bases. To elucidate the role of ...

A comparison between phosphine boranes and sulfides in their catalytic asymmetric deprotonation using organolithiums and sub-stoichiometric amounts of (-)-sparteine has revealed superior catalytic efficiency in the phosphine sulfide deprotonation.

The deprotonation kinetics of the DEA--C02 and the DIPA-COZ zwitterions have been studied in aqueous blends of an&es at 298 K. Amine mixtures investigated were: DEA-TEA, DEA-MDEA. DEL-DMMEA, DEA-DEMEA, DIPA-TEA, DIPA-MDEA, DIPA-DMME~ DIPA-DEMEA. FOG each blend the zwitterion deprotonation constant of the additonal base present in solution (i.e. the tertiary amine) was determined. The observed d...

The switching phenomena of conformation with p-electronic network through deprotonation– protonation processes were investigated by employing a series of 5,20-bis(a-oligothienyl) substituted hexaphyrins(1.1.1.1.1.1). They showed significant changes in the absorption and emission spectra with deprotonation, and returned to the initial state with protonation. Through NMR measurements and single c...

Levodopa (LD) is used to increase dopamine level for treating Parkinson's disease. The major metabolism of LD to produce dopamine is decarboxylation. In order to understand the metabolism of LD; the electronic structure of levodopa was investigated at the Density Functional DFT/B3LYP level of theory using the 6-311+G** basis set, in the gas phase and in solution. LD is not planar, with the amin...