Electrochemistry of 9,9′-spirobifluorene derivatives: 2-acetyl- and 2,2′-diacetyl-9,9′-spirobifluorene. Preparation of stereoisomeric 2,3-bis(9,9′-spirobifluoren-2-yl)butane-2,3-diols

Abstract

2-Acetyl-and 2,2'-diacetyl-9,9'spirobifluorene 1 and 2 were studied by cyclic voltammetry in dimethylformamide. The corresponding anion radicals show remarkable persistency in aprotic D M F. The (apparent) standard potentials are P = -1.77 V (SCE) and €" = -1.75 V for the (quasireversible) reduction of 1 and 2 to the anion radicals, respectively. Preparative electrolysis of 1 in DMF-Et,NCIO, (0.1 mol dm-3), with excess acetic acid as proton donor, furnished alcohol 3 and the diastereoisomeric pinacols 5 and 6, which were isolated and characterized. The diastereoisomeric excess, de, as evaluated (NMR) on the electrolyzed solution was only slightly in favour of the ( + ) compound. Spectroscopic properties of compounds 1-6 are, inter alia, the 13C NMR chemical shift for the spiro-carbon at 6 = 65.9 (TMS), and the fragmentation patterns in the mass spectra, with the 100% relative abundance of the molecular-ion M'+ in the case of the aromatic ketones 1 and 2. Some comments on the influence of conformations of 5 and 6 and of the presence of an intramolecular hydrogenbond in some intermediates and products are also presented.Molecules that contain two halves fixed at a 90" angle uiu a 0bonded network, each half bearing an aromatic, conjugated (proconducting) structure are now actively studied. In fact, they may be used as building blocks for molecular electronic based computing instruments, and, generally, for assembling single compounds that function as a self-contained electronic system. For this reason, we decided to study 9,9'-~pirobifluorene,~ its 2acetyl and 2,2'-diacetyl derivative^.^^' Additional interest in Paper 3/02480F

Dispirofluorene–Indenofluorene Derivatives as New Building Blocks for Blue Organic Electroluminescent Devices and Electroactive Polymers

“…[53] 9,9'-SBF was prepared according literature procedures. [65,70,71] IF was prepared in a four-step synthesis by a modified Wang procedure (see details in Supporting Information). [72] (2-Iodophenyl)carbamic acid tert-butyl ester (5): Sodium bis(trimethyl-A C H T U N G T R E N N U N G silyl)amide (8.2 mL, 16.4 mmol) was added dropwise to a stirred solution of 1 (1.8 g, 8.2 mmol) in dry THF (7.5 mL) at room temperature under an argon atmosphere.…”

“…9,9'-SBF was prepared according to literature procedures. [65,70,71] IF was prepared in a four step synthesis, by a modified Wang procedure (see details in the Supporting Information). [72] Scheme 2.…”

Comparative studies of the reduction of 2-naphthaldehyde, 9,9′-spirobi-(9H-fluorene)-2-carboxaldehyde and 2-fluorenecarboxaldehyde in nonaqueous solvents

“…Anodic oxidation leads to interesting polymerization reactions [4] as does oxidation of mono-and bisdithiafulvenyl-9,9 0 -spirobiflourene [7]. Reduction of 2-acetyl-and 2,2 0 -diacetyl-9-9 0 -spirobifluorene has been studied from an electrosynthetic viewpoint, as well as with qualitative voltammetric examination [2,3]. The analogous aldehydes, 2-carboxaldehyde-9,9 0 -spirobifluorene, (2), and 2,2 0 -dicarboxyaldehyde-9,9 0 -spirobifluorene were prepared by direct formylation of the parent spiro compound [5] and the preparative reduction of the former aldehyde in DMF was shown to produce a mixture of meso and dl 1,2-bis(2-spirobifluorenyl)-1,2-ethanediols, an electrohydrodimerization reaction [8].…”

“…9,9 0 -Spirobifluorene, (1), and its derivatives have been the subject of many electrochemical investigations [1][2][3][4][5][6][7][8][9]. The parent compound undergoes reduction to form a radical anion whose lifetime is long enough to allow easy detection by cyclic voltammetry [1].…”

Synthesis of some new spiroindoline derivatives incorporated with pyrazoloheterocycles

“…Photo and thermochromic properties of spiro derivatives have been studied [ 171. Electronic and spectroscopic properties of spirocyclic compounds have been investigated [ 18,193. Kinetic studies of solvent and pressure effects on thermal isomerization of spiro derivatives [20], studies of light-induced changes of the molecular charge in spironaphthoxazine compounds [21,22], and electrochemical studies on nitrospiro[indoline-naphthopyran] and 9,9'-spirobifluorene derivatives have been [23,24] investigated. Also, divers biological activities have been encountered in compounds having the indole ring system From all of the forgoing facts, together with the importance of the pyrazole derivatives , and as a continuation of our previous work [35-371, we report herein the synthesis of some new spiro-[indoline-3-pyrazoloheterocycles]-2-one derivatives.…”