Somasekhar Bondalapati

Stereoselective One-Pot, Three-Component Synthesis of 4-Aryltetrahydropyran via Prins-Friedel-Crafts Reaction

A diastereoselective one-pot, three-component Prins-Friedel-Crafts reaction was developed for the synthesis of 4-aryltetrahydropyran derivatives from the reaction of carbonyl compounds with homoallylic alcohol in the presence of arene promoted by boron trifluoride etherate.

Unveiling the mode of action of antibacterial labdane diterpenes from Alpinia nigra (Gaertn.) B. L. Burtt seeds.

The labdane diterpene, (E)-labda-8(17), 12-diene-15, 16-dial (compound A) and its epoxide analogue, (E)-8β, 17-Epoxylabd-12-ene-15, 16-dial (compound B) were isolated from the seeds of Alpinia nigra for the first time. The antibacterial activities of both compounds were evaluated against three Gram-positive and four Gram-negative bacteria, and flow cytometric analysis revealed that these compounds caused significant damage to the bacterial cell membranes. Further, field emission scanning electron microscope imaging and cell leakage analysis confirmed that the labdane diterpenes were responsible for bacterial cell membrane damage and disintegration. Our findings provide new insight into the broad-spectrum effects of two natural labdane diterpenes that may be useful in the future development of herbal antibiotic products.

A novel synthesis of oxabicyclo[3.3.1]nonanone via (3,5)-oxonium-ene reaction.

Oxabicyclo[3.3.1]nonanone can conveniently be prepared by the reaction of trans-p-menth-6-ene-2,8-diol and aldehyde or epoxide mediated by boron trifluoride etherate in good yields. The reaction proceeds via (3,5)-oxonium-ene-type reaction.

Diastereoselective Synthesis of Substituted Tetrahydrothiopyrans via (3,5)-Thionium–Ene Cyclization Reaction

Tetrahydrothiopyrans have been efficiently synthesized in good yields with excellent diastereoselectivity from aldehydes and substituted 5-methylhex-4-ene-1-thiol via (3,5)-thionium-ene cyclization reaction mediated by boron trifluoride etherate.

Lewis Acid Mediated Intramolecular C–C Bond Formation of Alkyne-Epoxide Leading to Six-Membered Nitrogen and Oxygen Heterocycles

Intramolecular C-C bond formation of oxygen- and nitrogen-tethered alkynes and epoxide mediated by Lewis acid under ambient conditions is described. A simple procedure for the synthesis of 3,6- and 5,6-dihydropyrans and 3,4-dehydropiperidines from acyclic building blocks in good yields without using any transition metal is shown.

Synthesis of 2,3-dihydro-4-pyranones from epoxides via intermolecular [4+2] cycloaddition reaction

An efficient synthesis of 2,3-dihydro-4-pyranones from epoxides and 3-alkoxycyclobutanones via an intermolecular [4+2] cycloaddition reaction, mediated by boron trifluoride etherate has been developed. The reaction is diastereoselective and gives trans diastereomers in excess.