Synthese von Benzofulvenen und Dibenzofulvenen über 1‐Chloralkyl‐acetate

Neuenschwander, Markus; Vögeli, Rudolf; Fahrni, Hans-Peter; Lehmann, H.; Ruder, Jean-Pierre

doi:10.1002/hlca.19770600332

Cited by 38 publications

(12 citation statements)

References 16 publications

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“…The lowest energy transition is seen at 323 nm, very comparable to the nearest fulvene analogue, 9-benzylidenefluorene, with a band at 326 nm, implying very little effect of the heterocyclic ring on the overall electronic delocalization. 29 This transition implies a delocalized π−π* transition involving the pyridyl ring. This is confirmed by the TD-DFT calculation, in this case the lower energy transition is at 347 nm (a shift of +26 nm), and in both cases the transitions originate from HOMO and HOMO-1 states, localized on the diphenylfulvene and the pyridine (Supporting Information, Figure S8).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Diimine Triscarbonyl Re(I) of Isomeric Pyridyl-fulvene Ligands: an Electrochemical, Spectroscopic, and Computational Investigation

2012

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The synthesis and characterization of a novel family of positively charged fac-[Re(bpy)(CO)(3)(L)]PF(6) (bpy = 2,2'-bipyridine) complexes are reported, where L is a pyridine functionalized in para or meta position with a fulvene moiety, namely, 4-fluoren-9-ylidenemethyl-pyridine (pFpy) and 3-fluoren-9-ylidenemethyl-pyridine (mFpy). The complexes were prepared in high yield (86%) by direct addition at room temperature of the corresponding pyridine to the tetrahydrofuran (THF) adduct fac-[Re(bpy)(CO)(3)(THF)][PF(6)] precursor. Both ligand and complex structures were fully characterized by a variety of techniques including X-ray crystallography. The complexes did not exhibit the expected triplet mixed metal-ligand-to-ligand charge transfer (MLLCT) emission, because of its deactivation by the non-emissive triplet excited state of fulvene. The absorption profile shows that the MLLCT is overshadowed by the fulvene centered π-π* transition of higher molar absorptivity as shown by time dependent density functional theory (TD-DFT) calculations. The position of the fulvene on the pyridyl ring has a large effect on this transition, the para position displaying a much higher absorption coefficient (21.3 × 10(3) M(-1) cm(-1)) at lower energy (364 nm) than the meta position (331 nm, 16.0 × 10(3) M(-1) cm(-1)).

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Section: ■ Results and Discussionmentioning

confidence: 99%

Diimine Triscarbonyl Re(I) of Isomeric Pyridyl-fulvene Ligands: an Electrochemical, Spectroscopic, and Computational Investigation

2012

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“…The residual solid was purified by chromatography to afford 5.06 g (93%) of the intermediate carbinol which was subsequently dehydrated as described for 4a to afford 3.55 g (73% overall yield) of 4b as a white solid; mp 75-77°C (Lit. 17 mp 76-77°C). 1 3 mmol, 47% ee) was added to a suspension of LiClO 4 (6.9 g, 65 mmol) in MeCN (6.5 mL) and the resulting mixture was stirred at r.t. until a homogeneous solution formed.…”

Section: -(Phenylmethylene)fluorene (4b); 17 Typical Proceduresmentioning

confidence: 99%

Synthesis of a 9-Fluorenone Derived β-Amino Alcohol Ligand Depicting High Catalytic Activity and Pronounced Non-linear Stereochemical Effects

Reddy¹,

Solà²,

Moyano³

et al. 2000

Synthesis

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The Jacobsen epoxidation of 9-alkylidenefluorenes 4a (ethylidene), 4b (benzylidene) and 4c (1-naphtylmethylene) with standard (R,R)-manganese salen catalyst has been studied. Both conversion and enantioselectivity depend on the steric bulk of the olefin substituent, best results being recorded with 4b (96% yield, 99% ee). The stereochemical course of the epoxidation of 4a is highly dependent on temperature and solvent, the ee of the resulting epoxide (S)-5a varying from 22% (-18°C, CH 2 Cl 2 ) to 49% (55°C, MTBE). The lithium perchlorate induced ring-opening of 5a with piperidine in MeCN affords a mixture of regioisomeric amino alcohols 3a/2a arising from the amine attack at the more substituted and less substituted carbons, respectively. The 3a/2a ratio can be modulated by the LiClO 4 concentration and the reaction temperature, and varies from 44:56 to 91:9. An independent, completely regiocontrolled synthesis of 3a has been developed involving ring-opening by the more substituted carbon of epoxide 5a with diisopropoxytitanium diazide, reduction of azidoalcohol 10a (H 2 , Pd/C) and cycloalkylation (1,5-dibromopentane, K 2 CO 3 ) of the amino alcohol 11a. The amino alcohol 3a exhibits a positive nonlinear stereochemical effect in its action as a ligand for the enantioselective addition of Et 2 Zn to benzaldehyde. The use of regiochemically pure 3a of >99% ee has been studied in the addition of Et 2 Zn to a representative family of aldehydes [19 examples, 93.6% mean ee]. The use of the directly available 9:1 mixture of 3a and 2a derived from 46-47% ee 5a as a ligand system for the enantioselective addition of Et 2 Zn to aldehydes [8 examples, 93.1% mean ee] is also reported.

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“…The reaction was completed by two hours of stirring a t room temperature (control by tlc, eluent C). Ether (100 mL) was added and the mixture was washed successively by NaHCO, (58), phosphate buffer (pH 7), and brine. Dry toluene (3 mL) was added to the dried (MgSO,) organic phase and ether was removed in vacuo.…”

Section: S'-o(fmm) Nucleotides 3a-dmentioning

confidence: 99%

The 9‐fluorenylmethyloxycarbonyl group as a 5′‐OH protection in oligonucleotide synthesis

Sonveaux

1989

Biopolymers

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Synthese von Benzofulvenen und Dibenzofulvenen über 1‐Chloralkyl‐acetate

Cited by 38 publications

References 16 publications

Diimine Triscarbonyl Re(I) of Isomeric Pyridyl-fulvene Ligands: an Electrochemical, Spectroscopic, and Computational Investigation

Diimine Triscarbonyl Re(I) of Isomeric Pyridyl-fulvene Ligands: an Electrochemical, Spectroscopic, and Computational Investigation

Synthesis of a 9-Fluorenone Derived β-Amino Alcohol Ligand Depicting High Catalytic Activity and Pronounced Non-linear Stereochemical Effects

The 9‐fluorenylmethyloxycarbonyl group as a 5′‐OH protection in oligonucleotide synthesis

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