Syntheses, Structures, and Reactivity of 2,5-Diboryl-1-alkylpyrroles and Di(1-alkyl-2-pyrrolyl)boranes

• Published in: European journal of inorganic chemistry Vol. 1999; no. 3; pp. 399 - 404
• Main Authors: Faderl, Jürgen, Deobald, Bernd, Guilard, Roger, Pritzkow, Hans, Siebert, Walter
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 01.03.1999; WILEY‐VCH Verlag GmbH; Wiley
• Subjects: 1-Alkylpyrroles; Boranes; Chemistry; Chemistry, Inorganic & Nuclear; Lithiation; Physical Sciences; Porphyrinogenes; Science & Technology; Tin-boron exchange; DICATION; PORPHYRIN; DERIVATIVES; THIOPHENE; SILICON-BRIDGED MACROCYCLES
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/(SICI)1099-0682(199903)1999:3<399::AID-EJIC399>3.0.CO;2-I

Reactions of 2,5‐dilithiated 1‐methylpyrrole (1a) with ClB(NR2)2 lead to the novel 2,5‐diboryl‐1‐methylpyrroles 2a and 2b. Accordingly, 2,5‐diboryl‐1‐benzylpyrrole 2d is obtained. 1a and Cl2BNiPr2 form the aminochloroboryl‐substituted derivative 2c and the di(5‐boryl‐2‐pyrrolyl)borane 4 in 29% and 15% yield, respectively. The 2,5‐distannyl‐1‐methylpyrrole 1c is used for the synthesis of the aryloxy‐boryl derivative 2e. Reacting monolithiated 1‐methyl‐ and 1‐benzylpyrroles with Cl2BNiPr2 yields the di(2‐pyrrolyl)boranes 3e and 3f, respectively. NMR and MS data are in agreement with the compositions of the compounds, which are confirmed by X‐ray structure analyses for 2a, 2b, 2d, und 3e.