Synthesis of some 5-trimethylsilylinodoles

Abstract

indole-1-acetate was hydrogenated at an initial pressure of 50 96-98'; v~~c l ' 1736 ( C 4 ester) and 1682 om-' (CZO amide); psi in 200 ml of ethanol in the presence of 1 g of platinum oxide.XZt' " sh 281 mp ( E SOOO), sh 289 (9700), and 314 (15,500).After 4 hr the catalyst was filtered, the filtrate wm concentrated, Anal. Calcd for C~HuNt07: C, 59.40; H, 5.98; N, 0.93. and the residual oil was chromatographed on neutral alumina.Found: C, 59.51; HI 5.98; N, 6.84.Fractions eluted with ether were wmbined and concentrated, and the residual solid wm recrystallized from ethyl acetatehexane to give 3.0 K (30%) of ethyl 3-carbethoxy-1,2,3,4-tetraAcknowledgment*-we thank Dr* R* *Imond and k h . M. c. Christie for many of the analytical and hydro-7,8-dimethox~-2-oxopyrimido [ 1,2-a] indole-1-acetate: mp spectral resdts. 5-Trimethylsilylindole has been synthesized starting from indole which waa N-benzylated and brominated in the 5 position, metalated to 5-lithio-N-benzylindolineJ and treated with trimethylchlorosilane to yield 5-trimethylsilyl-N-benzylindoline. Catalytic hydrogenolysis in the presence of acetic anhydride gave 5-trimethylsilyl-N-acetylindoline, which was hydrolyzed by KOH in diethylene glycol to btrimethylsilylindoline, which in turn was converted into 5-trimethylsilylindole by catalytic dehydrogenation in boiling xylene in the presence of palladium-charcoal. 5-Trimethylsilylgramines were synthesized. 5-Trimethylsilylgramine methiodide was converted into the nitrile by reaction with sodium cyanide and the latter waa hydrolyzed to btrimethylsilylindole-3-acetic acid, or reduced to 5-trimethylsilyltryptamine.

Access to C5-Alkylated Indolines/Indoles via Michael-Type Friedel–Crafts Alkylation Using Aryl-Nitroolefins

“…To prevent the N -alkylation, the nitrogen atom of indoline was protected by the benzyl group. The reaction of indoline with benzyl bromide in the conditions reported in the literature led to 1-benzylindoline ( 10a ) . Using a similar reaction, we also obtained the 1-benzyl-2-methylindoline ( 10b ) and ethyl 1-benzylindoline-2-carboxylate ( 10c ).…”

“…To overcome this problem, we explored a two-step protocol which has been successfully applied for debenzylation of 5-trimethylsilyl- N -benzylindoline . The first step of this protocol was the hydrogenolysis in the presence of acetic anhydride so that following the splitting off of the N -benzyl group the amino group was acetylated.…”

Fragmentation reactions of N‐benzyltetrahydroquinolines in electrospray ionization mass spectrometry: the roles of ion/neutral complex intermediates

“…The N ‐benzyltetrahydroquinolines were synthesized following the procedures described in the literature using tetrahydroquinoline and corresponding benzyl bromide. The structures were confirmed using 1 H NMR, 13 C NMR and HRMS after the purification of the crude products.…”

Immobilization of Cyclometalated Iridium Complex onto Multiwalled Carbon Nanotubes for Dehydrogenation of Indolines in Aqueous Solution

“…1-Benzyl-indoline was synthesized according to literature procedures: Indoline (0.6 g, 5 mmol) was added to sodium bicarbonate (525.0 mg, 6.25 mmol) in 3 mL H 2 O and the mixture was stirred at 90 °C. Benzyl chloride (630.0 mg, 5 mmol) was added dropwise for 1.5 h, and then the mixture was stirred for an additional 3.5 h. After the mixture was cooled, the organic phase was collected, and the aqueous layer was extracted with Et 2 O (20 mL × 3).…”

“…1-Ethylindoline was synthesized according to literature procedures: Indoline (0.6 g, 5 mmol) was added to sodium bicarbonate (525.0 mg, 6.25 mmol) in 3 mL of H 2 O. The mixture was stirred at 89.5 °C.…”