No abstract

We report herein the synthesis and biological evaluation of bile acid dimers linked through 1,2,3-triazole and bis-beta-lactam. The dimers were synthesized using 1,3-dipolar cycloaddition reaction of diazido bis-beta-lactams , and terminal alkynes derived from cholic acid/deoxycholic acid in the presence of Cu(i) catalyst (click chemistry). These novel molecules were evaluated in vitro for their antifungal and antibacterial activity. Most of the compounds exhibited significant antifungal as well as antibacterial activity against all the tested fungal and bacterial strains. Moreover, their in vitro cytotoxicities towards HEK-293 and MCF-7 cells were also established.

Asymmetric Tsuji–Trost allylation is one of the key chiral technologies for construction of pharmaceutically important compounds because of the high utility of alkenyl-substituted products. Particularly, the dehydrative system using allylic alcohols and protic nucleophiles has started to attract the attention of organic synthetic chemists from the viewpoints of atom and step economy, environmental benignity, and operational simplicity. In this paper, two types of new chiral CpRu catalysts, which have been developed on the basis of redox-mediated donor–acceptor bifunctional catalyst (RDACat) concept, are presented. Complementary use of the chiral catalysts has realized the syntheses of a wide rage of carbocyclic compounds, saturated N- or O-heterocyclic compounds with high reactivity, regioselectivity, enantioselectivity, productivity, and generality.

Chiral spirocarbocyclic skeletons are ubiquitous in natural products. An intramolecular Tsuji-Trost (T-T) α-allylation of simple cyclic ketones is a reasonable approach to construct chiral spriocarbocyclic motifs; however, it has been a challenging approach despite many excellent intermolecular examples. For the first time, this has been achieved by a Ru/H combined catalyst that dehydratively cyclizes racemic allylic alcohols comprising a simple ketone via simultaneous activation of the C=O and OH groups. This chiral technology facilitates the construction of various spirocarbocycles containing two contiguous spiro all-carbon quaternary and tertiary stereocenters. Among four possible stereoisomers, one stereoisomer can be selectively produced in high yield, enhancing the feasibility of the T-T strategy, particularly in the synthesis of spirocarbocycles.

Six new chiral 1,2-amino alcohol derivatives have been synthesized starting from (1R,2R)-2-amino-1-phenylpropane-1,3-diol. Asymmetric reduction of aryl ketones with in-situ generated oxazaborolidine from these amino alcohol derivatives and BH 3 ·Me 2 S afforded secondary alcohols with good yield and moderate to high enantiomeric excess. Results and DiscussionCommercially available [12] and inexpensive chiral amino alcohol (1R,2R)-2-amino-1-phenylpropane-1,3-diol 1, a precursor for the preparation of chloramphenicol, has been used by us for the synthesis of all six new chiral auxiliaries. The amino alcohols