Diastereoselective 2,3-diazidation of indoles via copper(II)-catalyzed dearomatization

The copper-catalyzed directed dearomatization of indoles with the assistance of directing groups has been developed for the synthesis of 2,3-diazido indolines with good yields and excellent diastereoselectivities in aqueous solution. The resultant 2,3-diazides can be smoothly converted to other functional groups, including vicinal diamines, triazoles and benzotriazoles, in a single step.     

Selective hydrogenation of unprotected indole to indoline over N-doped carbon supported palladium catalyst

Mesoporous N-doped carbon supported palladium catalyst Pd@CN0.132 was able to efficiently catalyze unprotected indole to indoline under mild conditions.In the aqueous system,a selectivity of 100% and conversion of 96% was achieved under 313 K and atmospheric hydrogen gas.     

In-vitro cytotoxicity of synthesized phthalide-fused indoles and indolines against HL-60 and HepG2 cells

Phthalide derivatives bearing indole or indoline moieties were successfully synthesized via eco-friendly method and were evaluated for their antiproliferative activity on HL-60 and HepG2 cell lines in vitro. At a final concentration of 100 μM, most of the compounds showed moderate potency on both the cell lines tested. Compound 3b bearing 5-chloro substituted indoline had the best potency against HL-60 and HepG2 cell lines with IC₅₀ values of 45.4 and 57.7 μM, respectively. It was also found that replacement of a conjugated indoline to indole moiety gave better antiproliferative activity on HL-60 cells by almost two-fold. Morphological observation demonstrated numerous fragmented nuclei which are indicative of apoptosis. Molecular docking studies predicted non-covalent interactions and H-bonding of selected compounds with the P2 binding hot spot of the anti-apoptotic protein, Bcl-2, formed by Asp108, Phe109, Met112, Leu134, Arg143, Ala146 and Val153. Overall, our work highlights the potential of synthesized phthalide-fused indoles or indolines as antitumor agents.     

The novel approach to indole alkaloids by using Pd(II)-catalyzed cyclization

The synthesis of indole skeleton by using Pd(II)-catalyzed cyclization of the urethane has been achieved. The urethanes with allylic alcohol were converted into vinyl indolines in good yield. The vinyl indoline was transformed into some intermediates of indole alkaloids.     

Rearrangement of Indolinesulfonamides to Sulfones Using Polyphosphoric Acid (PPA)

Unlike other N-alkylsulfonanilides, indolinesulfonamides hydrolyze in 98% sulfuric acid. Recent work in this laboratory has shown that rearrangement can be achieved by using polyphosphoric acid. A series of substituted indolinesulfonamides has been prepared and rearranged to their corresponding indoline arylsulfones.     

Transition-metal-free approach to synthesis of indolines from N-(ortho-chloromethyl)aryl amides and iodonium ylides

A transition-metal-free method for the synthesis of indolines has been developed. In the presence of K₂CO₃, the cyclization reaction of N-(ortho-chloromethyl)aryl amides and iodonium ylides proceeded smoothly at room temperature in moderate to good yields.     

Construction of nitrogen-heterocyclic compounds through zirconium mediated intramolecular alkene-carbonyl coupling reaction of N-(o-alkenylaryl)carbamate derivatives

Intramolecular alkene-carbonyl coupling reaction of N-benzyl-N-(o-alkenylaryl)carbamate derivative derived from o-aminostyrene, o-(aminomethyl)styrene and o-aminoallylbenzene smoothly proceeded by treating with zirconocene-butene complex to give the corresponding lactam derivative.     

Novel indoline dye tetrabutylammonium carboxylates attached with a methyl group on the cyclopentane ring for dye-sensitized solar cells

(2R,3aR,8bR)- and (2S,3aS,8bS)-2-Methyl indoline dye tetrabutylammonium carboxylates exhibited the highest conversion efficiency among four regio and stereo isomers. These indoline dyes also showed higher conversion efficiency than DN350.     

The synthesis of compounds related to the indole-indoline core of the vinca alkaloids (+)-vinblastine and (+)-vincristine

A series of α′-aryl-α′-carbomethoxycycloalk-2-en-1-ones, 16, has been prepared using the Pinhey arylation methodology for introducing the aromatic residue. Subjection of these compounds to Johnson iodination and Pd[0]-catalyzed Ullmann cross-coupling of the resulting α-iodocycloalkenones 11 with 2-iodonitrobenzene (5, X = I) then affords α,α′-diaryl-α′-carbomethoxycycloalk-2-en-1-ones of the general form 10. Reductive cyclization of this last type of compound gives the corresponding indoles 9a-f (n = 1-3), some of which resemble the indole-indoline cores of the clinically important alkaloids (+)-vinblastine (1) and (+)-vincristine (2).