Uthaiwan Sirion

Iodine catalyzes C-glycosidation of d-glucal with silylacetylene

Abstract A convenient method for C-glycosidation (alkynylation) with various silylacetylenes to d -glucal by iodine molecule via iodo–oxonium intermediates provided exclusively the α-acetylene glycoside products. Eleven successful examples are shown under this condition.

New substituted C-19-andrographolide analogues with potent cytotoxic activities.

Andrographolide, the major diterpenoid lactone from Andrographis paniculata, is toxic against cancer cells. In the present study, we investigated the structure-activity relationships (SARs) of 19 andrographolide analogues which were synthesized by modification at the three hydroxyl groups. A number of the andrographolide analogues showed much higher cytotoxic activities than that of the parent compound on cancer cells including P-388, KB, COL-2, MCF-7, LU-1 and ASK cells. SAR studies of the synthetic analogues indicated that the introduction of silyl ether or triphenylmethyl ether group into C-19 of the parent compound led to increase in toxicity against the cancer cells. The 19-O-triphenylmethyl ether analogue 18 showed higher cytotoxic activity than the potent anticancer drug ellipticine, and this analogue may serve as a potential structure lead for the development of new anticancer drugs.

An efficient method for the selective synthesis of 2-deoxy-2-iodo-glycosides by O-glycosidation of d-glucal using I2–Cu(OAc)2

An efficient and convenient method for the synthesis of 2-deoxy-2-iodo-O-glycosides from tri-O-acetyl-D-glucal with various alcohols by using I₂-Cu(OAc)₂ is described. The 21 examples of corresponding glycosides were obtained in high yields, with good anomeric selectivity.

12-Amino-andrographolide analogues: synthesis and cytotoxic activity

Andrographolide, a diterpenoid lactone of the plant Andrographis paniculata, has been shown to be cytotoxic against various cancer cells in vitro. In the present study, a series of β-amino-γ-butyrolactone analogues has been synthesized from naturally occurring andrographolide via one pot tandem aza-conjugate addition–elimination reaction. By using economic procedure without any base or catalyst at room temperature, the products obtained were in fair to excellent yields with high stereoselectivity. The cytotoxicity of all new amino analogues were evaluated against six cancer cell lines and revealed their potential for being developed as promising anti-cancer agents.

CONVERTIBLE FORMATION OF DIFFERENT GLYCOSIDE USING MOLECULAR IODINE

The observation of convertible formation between 2-deoxy-2-iodo-O-glycosides and 2,3-unsaturated glycoside was described. The selective formation of 2-deoxy-2-iodo-O-glycosides was found from the reaction of D -glucal with iodine in the excess alcohol acceptor or the addition of ceric ammonium nitrate as additive while the addition of a stoichiometric amount of alcohol in solvent favored 2,3-unsaturated glycosides formation.

One-pot synthesis of O-glycosyl triazoles by O-glycosylation-click reaction.

2,3-Unsaturated-glycosyl triazoles were synthesized in a simple one-pot process under mild condition via tandem O-glycosylation using iodine promoter and a mild CuAAC reaction. Thirty examples of a variety of O-glycosyl triazoles were obtained in good to excellent yields and α-anomeric selectivity.

One-pot three steps cascade synthesis of novel isoandrographolide analogues and their cytotoxic activity

An efficient one-pot synthesis of novel andrographolide analogues is reported from a naturally occurring and abundant andrographolide isolated from aerial parts of Andrographis paniculata. Reactions in the one-pot proceed through a cascade epoxide ring opening by aniline derivatives/intramolecular ring closing and oxa-conjugate addition-elimination reactions. This methodology produces a new series of 17-amino-8-epi-isoandrographolide analogues in fair to excellent yields with high stereoselectivity using an economic and environmental procedure without base or catalyst at room temperature. Twenty-five analogues were obtained and cytotoxicity of all new analogues were evaluated against six cancer cell lines to search for a new lead compound based on andrographolide structure.

Acid-ionic polymer as recyclable catalyst for one-pot three-component Mannich reaction

A recyclable solid-catalyst, acid-ionic polymer bearing imidazolium trifluoromethanesulfonate, [PS-Im][OTf] was presented as an efficient catalyst in a one-pot, three-component Mannich reaction of aldehydes, amines and ketones. The protocol was conducted successfully under mild, convenient and metal-free conditions to afford the corresponding products in moderate to excellent yields. In addition, the catalyst was reused four times with no significant loss in activity.

Synthesis and cytotoxic activity of 14-deoxy-12-hydroxyandrographolide analogs

Important anticancer cytotoxicological properties are reported from synthetic analogs of 14-deoxy-12-hydroxy-andrographolide, a compound that occurs in Andrographis paniculata, an indigenous Southeast Asia plant. Cytotoxicities of 15 synthesized 14-deoxy-12-hydroxy-andrographolide analogs were evaluated against a panel of cancer cell lines with some exhibiting much greater than the parent compound. For example analog 2j was 6–35 times more potent than the parent compound and the anticancer agent, ellipticin, on all cell lines except LU-1 cancer cells. With promising cytotoxicities and simple preparation, this compound has significant potential in the treatment of cancer.Graphical Abstract

One pot approach for the synthesis of bis-indole-1,4-disubstituted-1,2,3-triazoles

A new strategy for the synthesis of bis-indoletriazoles was developed using a sequential one-pot four-step procedure via I2 and H2SO4-SiO2 catalyzed Friedel-Crafts reactions of indole with aldehyde followed by N-alkylation with propargyl bromide, azidation, and copper(I)-catalyzed azide alkyne cycloaddition (CuAAC). The reaction proceeded smoothly at room temperature in a short time, and a series of bis-indoletriazoles were obtained in good to excellent yields proving the generality of this one-pot methodology.