A simple and mild method for tetrahydropyranylation of alcohols is reported at room temperature using a catalytic amount of 3-methylimidazolinium hydrogensulfate([Hmim]HSO4) as a green, efficient and reusable catalyst. Using solvent-free conditions, non-toxic and inexpensive materials, modest and clean work-up, short reaction times and high yields of the products are the advantages o...

Buffer catalysis and solvent kinetic isotope effects in the cyclization of methyl-substituted ethyl hydantoates with ωN-methyl (MUE) and ω-N-phenyl groups (PUE) have been studied in an attempt to elucidate the changes in mechanism and eventual reversal of relative reactivities caused by increasing the number of substituent methyl groups (the gem-dimethyl effect). (Rate constants for the hydroxi...

The principal objective of this lecture is to describe the efficacy of organometals as electron donors, and to show how this property dominates many aspects of their chemistry. First, the structural effects of alkyl ligands (B) on the highest occupied molecular orbital (HOMO) of the neutral alkylmetals, R4Sn, R4Pb and R2Hg, are probed by photoelectron spectroscopy. The chemical properties of th...

background and objectives: betulinic acid (ba), oleanolic acid (oa) and ursolic acid (ua) are well-known pentacyclic triterpenoids (pts), which are produced by plants. they possess a variety of beneficial effects including anti-inflammatory, hepatoprotective, antitumor, anti-hiv, antimicrobial, gastroprotective, and antihyperlipidemic activities. in the present study, quantitative determination...

Silent information regulator 2 (Sir2) enzymes catalyze NAD+-dependent protein/histone deacetylation, where the acetyl group from the lysine epsilon-amino group is transferred to the ADP-ribose moiety of NAD+, producing nicotinamide and the novel metabolite O-acetyl-ADP-ribose. Sir2 proteins have been shown to regulate gene silencing, metabolic enzymes, and life span. Recently, nicotinamide has ...