N-indolyl

Also the acid-promoted ri (N)-indolyl T( (N)-indolenine conversion on CpRh(PPh3)(NO) shown in Eq. 6.7 has been reported by Gladysz [33]. 

Again, this is an interesting model for a possible way of adsorbing and hydrogenating indoles on solid catalysts at the early stages of HDN. Ti (N)-Indolyl complexes are activated toward protonation at the P-carbon atom, which transforms them into r (N)-indolenine derivatives (See e.g. Eq. 6.7) [33]. 

Benzoyl chloride and derivatives acylate 2-amino-4-aryithiazoles in dioxane in yields of 80 to 90% (249, 250). The location of the acyl group on the exocyclic N has been demonstrated by the fact that the benzoyla-tion product is identical to the benzamidothiazole synthesized from benzamide and 2-bromothiazole (251). 3-Indolyl acetic acid chloride (89) acylates 2-aminothiazole in pyridine (Scheme 62) (81). 

In addition to the radical ipso-substitution of indolyl sulfones producing stannanes described earlier <96T11329>, Caddick has also reported an approach to fused [l,2-a]indoles based on the intramolecular cyclization of alkyl radicals. Thus, treatment of 112 with BuaSnH leads to the fused ring derivatives 113 (n = 1-4) <96JCS(P1)675>. 

In an alternate mode of radical cyclization, indolyl-2-radicals generated from the corresponding 2-bromo derivatives 152 (n=l-3) undergo intramolecular reactions with appended aromatic rings to afford fused [ 1,2-a]indoles 153 <00TL4209>. 

The reaction of nitrones with indoles in the presence of HC1 gives indolyl N-hydroxylamines. In the presence of Me SiCl symmetrical diindolylalkanes are formed (Scheme 2.193) (679, 680). 

A (Alternative) JCS 3175(1952). 2 g 3-indolyl-acetic acid (preparation given elsewhere here), 1.55 g freshly fused sodium acetate, 5 ml acetic anhydride. Heat 135-140° on oil bath for eighteen hours cool, wash with water and extract with CHCl3-ether (1 4). Wash organic phase with 3X20 ml saturated KHC03 and dry, evaporate in vacuum to get the l-acetyl-3-indolyl-acetone, which can be reduced to the alpha-methyl-tryptophol derivative with lithium aluminum hydride, and then converted to the dialkyl-tryptamine as already described (as can (I)), or used in step B, or reduced to (I) as follows dissolve 1 g in 1 ml 1 N Na-methoxide in methanol and 60 ml methanol, and keep at 40° for 10 minutes acidify with dilute HC1 and extract with ether. Dry, evaporate in vacuum to get (I) (recrystallize-methanol). 

The invention of the triflate (trifluoromethylsulfonyl) group — one of the world s best leaving groups — has led to its use in palladium chemistry [42]. Conway and Gribble described the synthesis of 3-indolyl triflate 34 [12] and 2-indolyl triflate 35 from oxindole [43]. Mdrour synthesized the N-phenylsulfonyl derivative 36 by employing a Baeyer-Villiger oxidation of the appropriate indolecarboxaldehyde [44],... 

A particularly elegant domino Heck reaction involving 4-bromoindole and bromo(indolyl)maleimide 251 to give N-methylarcyriacyanin A (252) in one operation was reported by Steglich [173]. This alkaloid could also be prepared from triflate 253 in higher yield in a heteroaryl Heck reaction. 

Tryptamine derivatives (26) were reacted with EMME to give N-[2-(3-indolyl)ethyl]aminomethylenemalonates (27) in nearly quantitative yields (77H1699 79MI1). 

The internal hydrogen bond (N—H—N) is responsible for suppression of cis-trans isomerization in the singlet excited state of cA-l-(2-indolyl)-2-(2-pyridyl)ethene (32) of reaction 13. Clearly, the reverse isomerization is possible125. On the contrary, irradiation of c -l-(2-pyrrolyl)-2-(2-quinolyl)ethene126 (35) induces the isomerization to 34. The isomerization (cis-trans) is possible because the excitation allows the tautomerization of 35 to 36 (equation 14). 

Alkali metal borohydrides are frequently used for the reduction of rc-electron-deficient heteroaromatic systems, but reduction of jt-electron-excessive arenes is generally possible only after protonation of the systems [e.g. 35-37]. The use of tetra-n-butylammonium borohydride under neutral conditions for the conversion of alkylindoles into indolines [38] is therefore somewhat unusual. Reduction of indoles by diborane under strongly alkaline conditions involves the initial interaction of the indolyl anion with the diborane to form an amino-borane which, under the basic conditions, reacts with a second molecule of diborane to produce the indoline [39]. The reaction of tetra-n-butylammonium borohydride with indoles could also proceed via the intermediate formation of diborane. 

Taguchi and associates (117) treated 3,3-dimethyl-3H-indole with p-chloroben-zoyl chloride in pyridine, and obtained two crystalline compounds in addition to l-(p-chlorobenzoyl)-3,3-dimethylindolin-2-ol. These two products had the molecular formula C27H25ON2CI, and a tricyclic structure with two benzo moieties was assigned. Dave and co-workers (118) questioned the structure on the basis of mechanistic considerations, and presented evidence that the products are atropisomers of 1 -(p-chlorobenzoyl)-2-(2,3-dimethyl-1 -indolyl)-3,3-dimethylin-doline (75) about the C—N axis. The barrier to rotation about the C—N bond... 

We investigated the possibility that the N-linked 2-methylimidazole ring might not be the optimum one for 5-HT3 antagonist activity and considered the possibility that C-linked imidazole derivatives might have advantages. One of the first compounds prepared was the indolyl ketone (27), which was chosen on grounds of accessibility and synthesized by standard reactions from the protected aldehyde (26) (Scheme 7.4) [61]. 

Dabiri M, Salehi P, Baghbanzadeh M, Shakouri M, Otokesh S, Ekrami T, Doosti R (2007) Efficient and eco-friendly synthesis of dihydropyrimidinones, bis(indolyl) methanes, and N-alkyl and N-arylimides in ionic liquids. J Iran Chem Soc 4 393 01 Legeay JC, Eynde JJV, Bazureau JP (2008) Ionic liquid phase organic synthesis (loLiPOS) methodology applied to the preparation of new 3,4-dihydropyrimidine-2(lH)-ones bearing bioisostere group in N-3 position. Tetrahedron 64 5328-5335... 

Similarly, 2-iodoanilides of indolyl acetic acid 15 lead to the corresponding 7,12-dihydroindolo[3,2-d][l]benzazepin-6(5H)-ones 16 (Equation (3) (2005TL8177)). Contrary to N-phenylsulfonyl derivatives lla,b and EOM protected species 13a,c, Boc-derivatives 14b and 15a do not tolerate these reaction conditions, and their fast decomposition has been observed. 

The reactive indolo-2,3-quinodimethanes are generated in situ generally from N-protected 2,3-disubstituted indoles (514,515). Generation of reactive indolo-2,3-quinodimethanes was achieved by fluoride-induced, 1,4-elimination of silylated indolyl ammonium salts, and was applied in the synthesis of substituted tetrahydrocarbazoles (516). Subsequently, the iodide-induced 1,4-elimination of ]V-benzoyl-2,3-bis(bromomethyl)indole (534) methodology was developed for the synthesis of reactive indolo-2,3-quinodimethanes and was applied for the first time in the synthesis of substituted carbazoles (e.g., 536) (517) (Scheme 5.14). 

Ishikura et al. reported the total synthesis of ellipticine (228) starting from N-Boc indole (1256) and the vinyl bromide 1258 (719-721). This methodology involves a palladium-catalyzed, tandem cyclization-cross-coupling reaction of the indolyl borate 1257 with the vinyl bromide 1258 as the key step. Using a literature procedure, the vinyl bromide 1258 was prepared as an E/Z mixture starting from CIS- and trans-crotyl alcohol. The indolyl borate 1257 was generated in situ from... 

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