Reaction of allenylmagnesium and allenylindium bromides with nitrile oxides: synthesis of novel 5-butynyl- and 5-methylisoxazoles

5-Butynylisoxazoles were obtained in high yields through a domino addition, C–O heterocyclization involving allenylmagnesium bromide and benzonitrile oxide in dry THF, in which the corresponding 5-methylisoxazoles were isolated in trace amounts. However, when the reactions were attempted in aqueous media using allenylindium bromide, 5-methylisoxazoles were formed as the sole products in high yields

Domino synthesis of indenols and alkyl-indene ethers under modified Vilsmeier conditions

Indenols are produced in high yields through domino reactions, when electron-rich trans-stilbenes and other trans aryl–alkyl olefins were subjected to Vilsmeier formylation in the presence of excess POCl3 in a one-pot procedure. The method is even suitable for converting aryl–alkyl carbinols (precursors for olefins) directly into indenols. The corresponding indene ethers could be prepared in high yields directly when less reactive a,b-unsaturated aldehydes were subjected to cyclization in alcoholic HCl

Catalytic transfer hydrogenation reactions of PEG-bound succinyl esters

Various substrates bound to polyethylene glycol (PEG) through succinyl ester linkages were cleaved under catalytic transfer hydrogenation conditions. The substrates with unsaturated functions also underwent hydrogenation. The protocol was found to be suitable for substrates having acid and base labile functional groups

Development of novel lipidated analogs of picroside as vaccine adjuvants: Acylated analogs of picroside-II elicit strong Th1 and Th2 response to ovalbumin in mice

The acylated analogs of picroside-II were synthesized and tested for immune-adjuvant activity in the presence of weak antigen ovalbumin found to stimulate anti-OVA IgG titer, neutralizing antibody (IgG1 and IgG2a) titer as well as the production of soluble mediators of a Th1 response (IL-2 and IFN-�) and Th2 response (IL-4) and proliferation of T lymphocytes sub-sets (CD4/CD8). Furthermore, these modified analogs of picroside-II were able to elicit a substantial increase in anti-OVA IgG when compared with OVA alone. These results support the use of acylated analogs particularly PK-II-3 and PK-II-4 as potent enhancer of antigen-specific Th1 and Th2 immune responses and thus are promising immune-adjuvant candidate for vaccines

Regio-selective acylation of biologically important iridoid glycosides by Candida antarctica lipase

Lipase catalyzed regio-selective acylation of five iridoid glycosides viz., picroside I&II, catalpol, agnuside and negundoside in the presence of various acyl donors such as vinyl acetate and p-nitrophenyl alkanoates was studied. The regio-selectivity of enzymatic acylation and yieldswere found to vary amongst different substrates. Monoacylated products were isolated with all the substrates under scrutiny indicating high regio-selective nature of such transformations. A series of acyl esters of picroside-I, picroside-II, catalpol, agnuside and negundoside have been synthesized by this enzymatic trans-esterification methodology

Design and synthesis of spiro derivatives of parthenin as novel anti-cancer agents

Several novel spiro derivatives of parthenin (1) have been synthesized by the dipolar cycloaddition using various dipoles viz; benzonitrile oxides, nitrones and azides with exocyclic double bond of C ring(a-methylene-g-butyrolactone). Majority of the compounds exhibited improved anti-cancer activity compared to the parthenin, when screened for their in vitro cytotoxicity against three human cancer cell lines viz., SW-620, DU-145 and PC-3. In vivo screening of select analog revealed improved anti-cancer activity with low mammalian toxicity as compared to parthenin. The results of the cytotoxicity pattern of these derivatives reveals the SAR of these sesquiterpinoid lactones and possible role of a,b-unsaturated ketone of parthenin in inhibiting NF-kB. A mechanistic correlation of anti-cancer activity along with in vivo and western blotting experiments has been described

Dengue

Lecture 49 ISBN e-book : 9781615045754International audienc