4756-25-6

Upstream product

• 7253-07-8 (9H-fluoren-9-yl)triphenylphosphonium bromide 
• 4440-33-9 fluorenone imine 
• 603-35-0 triphenylphosphine 
• 1940-57-4 9H-fluoren-9-yl bromide 

Downstream Products

• 2871-87-6 p-methoxybenzylidene fluorene 
• 136036-45-8 9-[(E)-3-(2-Nitro-phenyl)-allylidene]-9H-fluorene 
• 2084-73-3 9-(2-chloro-trans-cinnamylidene)-fluorene 
• 1643-48-7 9-(2-bromobenzylidene)fluorene 
• 2311-84-4 9-(2-nitrobenzylidene)-9H-fluorene 
• 791-28-6 Triphenylphosphine oxide 
• 75637-36-4 fluorenylidene phthalide 
• 3878-45-3 triphenylphosphine sulfide 
• 72403-81-7 6'-Methyl-7'-phenylspiro<9H-fluoren-9,3'-<3H>pyrazolo<5,1-c><1,2,4>triazol> 
• 486-25-9 9-fluorenone 
• 4421-51-6 9-(3-nitrobenzylidene)-9H-fluorene 
• 6954-71-8 9-(4-nitrobenzylidene)-9H-fluorene 
• 1749-21-9 N-(9H-Fluoren-9-ylidenemethylene)aniline 
• 5751-46-2 1,1-(o-biphenylene)-3,3-diphenylprop-1-ene 

Relevant academic research and scientific papers

Polymorphism and benzene solvent controlled stimuli responsive reversible fluorescence switching in triphenylphosphoniumfluorenylide crystals

Triphenylphosphoniumfluorenylide (TPPFY), a fluorescent fluorene attached molecule, showed polymorphism and benzene solvent induced aggregation enhanced emission (AEE) in the solid state. Crystallization from CH3CN produced non-fluorescent crys

Inner workings of a cinchona alkaloid catalyzed oxa-Michael cyclization: Evidence for a concerted hydrogen-bond-network mechanism

Cinchona alkaloids catalyze the oxa-Michael cyclization of 4-(2-hydroxyphenyl)-2-butenoates to benzo-2,3-dihydrofuran-2-yl acetates and related substrates in up to 99 % yield and 91 % ee (ee=enantiomeric excess). Catalyst and substrate variation studies reveal an important role of the alkaloid hydroxy group in the reaction mechanism, but not in the sense of a hydrogen-bonding activation of the carbonyl group of the substrate as assumed by the Hiemstra-Wynberg mechanism of bifunctional catalysis. Deuterium labeling at C-2 of the substrate shows that addition of RO-H to the alkenoate occurs with syn diastereoselectivity of ≥99:1, suggesting a mechanism-based specificity. A concerted hydrogen-bond network mechanism is proposed, in which the alkaloid hydroxy group acts as a general acid in the protonation of the α-carbanionic center of the product enolate. The importance of concerted hydrogen-bond network mechanisms in organocatalytic reactions is discussed. The relative stereochemistry of protonation is proposed as analytical tool for detecting concerted addition mechanisms, as opposed to ionic 1,4-additions. Secret of cyclization: The cinchona alkaloid catalyzed asymmetric oxa-Michael cyclization of 2′-hydroxyphenyl-2-butenoates to benzodihydrofurans proceeds by a highly enantio- and diastereoselective syn-specific addition mode (see scheme). Transition-state activation of the carbonyl group by hydrogen bonding to the catalyst is excluded. This represents a clear-cut demonstration of the importance of concerted hydrogen-bond network mechanisms in cinchona-based asymmetric organocatalysis. Copyright