163. Alkylation of the aromatic nucleus. Part VI. Fluorene

Abstract

When fluorene is alkylated by thermal decomposition of ethyl, isopropyl, or s-butyl benzenesulphonate in a moderate excess of fluorene, substitution occurs in the nucleus at all the possible positions. The proportions of the isomeric alkylfluorenes in each alkylation product have been determined and these values compared with those obtained by other methods of alkylation.IN this work we examined the alkylation of fluorene by the thermal decomposition of ethyl, isopropyl, and s-butyl benzenesulphonate in fluorene, especially with regard to the distribution of the alkyl group in the nucleus, and we compared these results with those of other substitution reactions of fluorene. The results are summarised in the Table, together with alkylations by the alcohol or alkyl halide with aluminium chloride as catalyst. No precise figures can be given for experiments 7-10, for in these some dialkylfluorenes were also formed which could not be separated sufficiently cleanly. Alkylation of fluorene. Method

Homopolymerization and copolymerization of N‐substituted maleimides with chiral anionic initiators

“…9H-fluorene-1-carboxylic acid (3) was synthesized from fluoranthene (1) as described in the literature; yield 88%. 32,33 9H-fluorene-1-carbonyl chloride (4) was prepared by refluxing compound (3) with SOCl 2 for 4 h and then removed from the solvent under vacuum; yield 95%. L-valinol or D-valinol (5) was obtained from the reduction of L-valine or D-valine by NaBH 4 and I 2 ; yield 80%.…”

Clemmensen reduction of 2-acetylfluorene. Pathways for the formation of 2,3-di(2-fluorenyl)butane and its homologues

“…3.3-Di(2-fluorenyl)-2-butanone (6). A 100-ml portion of acetic acid containing 0.53 g of 5 and 1.3 g of polyphosphoric acid was refluxed for 6 h. After cooling, the reaction mixture was poured into 500 ml of water and the precipitate was purified by means of aluminacolumn chromatography in benzene and recrystallization from ethanol to afford 0.43 g (86%) of 6: mp 156-157 °C dec; ir Gc=o) 1705 cm-1; mass spectrum m/e 400 (M+), 357, 342,191,178,165, and 43; NMR (CDClg) 2.00 (s, -CHS), 2.20 (s, -COCHs), 3.87 (s, 2 >CH2), and 7.08-7.90 ppm (m, aromatic H).…”

“…Oxidation of 3,3-Di(2-fluorenyl)-2-butanone (6). A mixture of 6 (1.0 g) and KMn04 (11 g) in acetone (70 ml) was refluxed for 2 h to A solution of 6 (2.0 g), sodium dichromate (20 g), a few drops of H2S04, and acetic acid (60 ml) was refluxed for 3.5 h; 0.68 g (35%) of…”

Bi(III)-Catalyzed Intermolecular Reactions of (Z)-Pent-2-en-4-yl Acetates with Ethynylarenes for the Construction of Multisubstituted Fluorene Skeletons through a Cascade Electrophilic Addition/Cycloisomerization Sequence

“…Consequently, they have drawn considerable interest for synthetic chemists. The classical method for the synthesis of fluorenes includes addition of organometals to 9-fluorenones; Friedel–Crafts ring closure of biarylmethanols, which utilizes a large excess of strong Brønsted acids such as HCl/HOAc1k or PPA at refluxing temperatures, or an equal or excess amount of BF 3 ·Et 2 O; Friedel–Crafts alkylation of fluorenes; metal-catalyzed or -mediated reactions including Pd-catalyzed rearrangement reactions; Pd-catalyzed annulative reaction of dihalobenzenes with hindered Grignard reagents; activation of C–F/C–H bonds of o -arylated α,α,α-trifluorotoluene derivatives, etc. Although these methods are effective for the synthesis of fluorenes, they have certain drawbacks, for example, a strong acid medium or a stoichiometric amount of Lewis acid sometimes is required.…”