Pyrrole 1- benzenesulfonyl

In order to exploit the reactions of the C-lithio derivatives of iV-unsubstituted pyrroles and indoles, protecting groups such as t-butoxycarbonyl, benzenesulfonyl and dimethyl-amino have been used 81JOC157). This is illustrated by the scheme for preparing C-acylated pyrroles (211) (8UOC3760). 

CF3CO2H, Me2S, 40-60 min, 100% yield, imidazole = His(Tos). The related benzenesulfonyl group has been used to protect pyrroles and indoles and is cleaved with NaOH/H20/dioxane, rt, 2 h3 ... 

To exploit the reactions of the C-lithio derivatives of N-unsubstituted pyrroles and indoles, N-protecting/masking groups such as ferf-butoxycarbonyl, terZ-biitylcarbamoyl, benzenesulfonyl, dimethylamino, and dimethylaminomethyl must be used. This is illustrated by a route to G-acylated pyrroles 441. Another very useful process involves N-lithiation, N-carbonation, and lithiation of the resulting indol-l-ylcarboxylate at C(2) reaction with an electrophile and loss of carbon dioxide during work-up give N-unsubstituted 2-substituted indoles, for example, 2-haloindoles in excellent yields. 

Azaindoles are readily acylated on the pyrrole nitrogen by warming on a water bath with acid anhydrides or with acid chlorides in the presence of carbonate or pyridine. Good yields were obtained by this procedure for the following compounds l-acetyl-7-azaindole, 1-benzoyl- and l-benzenesulfonyl-7-azaindole, l-benzoyl-2-methyl-7-azaindole, 1-ethoxycarbonyl- and l-chloroacetyl-7-azaindole, l-acetyl-3-cyano-7-azaindole, 1-benzoyl-4-azindole, and 1-acetyl- and l-benzoyl-2,5-dimethyl-4-azaindole. The only reported failure was with 5-methyl-2-phenyl-4-azaindole, which failed to react with acetic anhydride or benzoyl chloride. 2-Methyl-7-azaindole-3-acetic acid was acylated by treatment of its ierGbutyl ester with sodium hydride in dimethylformamide, followed by p-chlorobenzoyl chloride. ... 

An identical procedure can be used for the formation of W-benzenesulfonylpyrrole. Typical quantities which may be used are potassium metal (10 g, 256 mmol), pyrrole (25 mL, 19.3 g, 288 mmol) and W-benzenesulfonyl chloride (45.1 g, 255 mmol). The material is obtained as a pale brown solid, which is purified by recrystallization without filtration followed by drying in vacuo at 45 C to give pale brown crystals [yield 30.5 g, 57.6 %, m.p. 87-89 C (lit. value 89-89.5 C)1. 

Preparation of AZ-benzenesulfonyl-3(6-bromohexanoyl)pyrrole and hydrolysis to 3-(6-bromohexanoyl)pyrrole [Scheme 2(ii) and (iii)]... 

In a round-bottomed flask (1 L) equipped with a condenser /V-benzenesulfonyl-3(6-bromohexanoyl) pyrrole (12.0 g, 31.3 mmol) is added together with a mixture of 1,4-dioxane (300 mL) and NaOH solution (5 M, 300 mL). The reaction mixture is stirred at room temperature for 48-72 h until thin layer chromatography (TLC) indicates the absence of starting material. ... 

Type Ilbd cyclocondensation reactions between isocyanide-based reagents and electron deficient alkenes or alkynes provides a convenient S3mthetic approach to highly functionalized pyrroles. The cyclocondensation between tosyl methyl isocyanide (TosMic) and 1,2-bis(benzenesulfonyl)ethene provided 3,4-bis(benzenesulfonyl)p)nTole 37 <05JHC333>. 

Perfluoroalkyl radicals can be generated from perfluorosulfonyl chloride using RuCljCRPh,), as a catalyst. In the presence of 1-substituted pyrroles good yields of 2-perfluoroalkylpyrroles were obtained with N-substituents such as acetyl, benzenesulfonyl or trimethylsilyl. With tr/s-isopropylsilyl, however, 3-substitution was preferred. <94SC2049, 94JCS(P1)1339>... 

A mixture of pyrrole, K, and tetrahydrofuran stirred and refluxed gently until all of the metal has reacted, heating discontinued, the slurry of the resulting pyrrolylpotassium dil. with solvent, a soln. of benzenesulfonyl chloride in tetrahydrofuran added dropwise during 0.5 hr., and stirred 14-18 hrs. at room temp. 1-benzenesulfonylpyrrole. Y 87%. F. e. s. E. P. Papadopoulos and N.F. Haidar, Tetrah. Let. 1968, 1721. 

A mixture of 1.5 g crude 1-benzenesulfonyl-1 //-pyrrol-3-yl-4-aminophenyl-methanone,... 

Havinga et al. prepared a series of poly(o)-(pyrrol-3-yl)alkanesulfonates) for electrochemical study [7] (Figure 20.34). Their synthetic route involved protecting the A-position with benzenesulfonyl chloride to form the A-phenylsulfonyl derivative. The pyrrole was then acylated at the 3-position of pyrrole with a o>-haloacid chloride under Freidel-Crafts conditions, followed by a Clemmensen reduction to yield the... 

---