Y. Venkateswarlu

Zeolite Catalyzed Synthesis of bis (Indolyl) Methanes

Abstract HY-Zeolite is found to be a versatile catalyst for the electrophilic substitution reaction of indoles with carbonyl compounds to afford the corresponding bis(indolyl) methanes in good yields. #IICT Communication No. 011208.

NEW LAMELLARIN ALKALOIDS FROM AN UNIDENTIFIED ASCIDIAN FROM THE ARABIAN SEA

Abstract An unidentified ascidian from the Arabian Sea contained nine new alkaloids of the lamellarin class together with lamellarin N. The structures of the 20-sulfate derivatives of lamellarins T, U, V, and Y ( 1–4 ) and lamellarins T - X ( 5–9 ) were identified by interpretation of spectroscopic data. This is the first report of lamellarin sulfates.

A new BIS-Andrographolide Ether from Andrographis paniculata Nees and evaluation of anti-HIV activity

Novel bis-andrographolide ether (1) and six known compounds andrographolide, 14-deoxy-11,12-didehydroandrographolide, andrograpanin, 14-deoxyandrographolide, (±)-5-hydroxy-7,8-dimethoxyflavanone, and 5-hydroxy-7,8-dimethoxyflavone have been isolated from the aerial parts of Andrographis paniculata and their structures were established by spectral data. All the isolates were tested for the anti-HIV and cytotoxic activity.

Rameswaralide, a novel diterpenoid from the soft coral Sinularia dissecta

Abstract Rameswaralide ( 4 ), a novel diterpene having a 5-7-6 tricyclic skeleton has been isolated along with known terpenes, africanene, 4,5- seco -african-4,5-dione, β-elemene and isomandapamate ( 3 ) from the soft coral Sinularia dissecta from the Mandapam coast, South India. The structure and stereochemistry of rameswaralide ( 4 ) were determined using spectroscopic methods and confirmed by selective reduction of the unusually stable enol group of 4 to form dihydrorameswaralide ( 5 ).

Bismuth triflate catalyzed conjugate addition of indoles to α,β-enones

Reaction of indoles with electron deficient olefins under the influence of bismuth triflate has been studied at ambient temperature and affords the corresponding 3-alkylated indoles in excellent yields.

A mild and efficient method for chemoselective deprotection of acetonides by bismuth(III) trichloride

Acetonides undergo chemoselective deprotection to afford the corresponding 1,2-diols in excellent yields using bismuth trichloride in acetonitrile/dichloromethane at ambient temperature.

Mandapamate, a diterpenoid from the soft coral sinularia dissecta

Mandapamate (3) is a diterpene with an unusual carbon skeleton from the soft coral Sinularia dissecta. The structure of mandapamate(3) was elucidated by interpretation of spectral data, particularly extensive NMR experiments, and was supported by a mechanistic hypothesis for its formation and molecular modelling.

A new triterpenoid from the fern Adiantum lunulatum and evaluation of antibacterial activity

A new triterpenoid, 22,29xi-epoxy-30-norhopane-13beta-ol (1) was isolated together with six known compounds viz., fern-9(11)-en-6alpha-ol. fern-9(11)-ene, fern-9(11)-en-25-oic acid, fern-9(11)-en-28-ol, filicenol-B, adiantone and oxidation product of fern-9(11)-en-6alpha-ol obtained as 6-oxofern-9(11)-ene from the whole plant of Adiantum lunulatum, and their structures were elucidated by means of spectroscopic analysis and antibacterial evaluation of these compounds were conducted.

An immunosuppressive tryptophan-derived alkaloid from Lepidagathis cristata

An immunosuppressive, tryptophan-derived alkaloid cristatin A (1), and two known compounds, cycloartenol and stigmasta-5,11(12)-diene-3 beta-ol, were isolated from the whole plant Lepidagathis cristata Willd. The structures of the isolates were established by interpretation of their spectral data.

Zirconium(IV) Chloride Catalyzed Synthesis of 2,3‐Unsaturated C, N, O, S, and Heteroaromatic Glycosylation in the Ferrier Rearrangement

Abstract The reaction of tri‐O‐acetyl‐D‐glucal with nucleophiles to afford the corresponding 2,3‐unsaturated glycopyranosides in excellent yields by zirconium(IV) chloride in acetonitrile at ambient temperature has been demonstrated. #IICT Communication No 021011