9-Phenylfluorenyl

In weaker acid systems, other reactions involving the triplet state supervene to the exclusion of dimerization. Photolysis of 85 in 3-3% sulfuric acid, 96-5% acetic acid, and 0-2% water gave as products tri-phenylmethane (93), 9-phenylfluorene (94), 6is-9-phenylfluorenyl peroxide (95) and benzophenone (96). When benzene was present, tetra-phenylmethane (97) was also formed in addition to the other products. When the triphenylmethyl cation is irradiated in 3-3% H2SO4, 80 1% HOAc, 16-4% toluene, and 0-2% H2O, the products observed were... 

The volume concludes with the preparation of four useful starting materials. The highly electrophilic tricarbonyl reagent DIMETHYL MESOXALATE finds application as a two-electron component in various pericyclic processes. 9-BROMO-9-PHENYL-FLUORENE is becoming increasingly used for the protection of primary amines, particularly amino acids and amino esters. Two methods for introducing the 9-phenylfluorenyl group are illustrated in the preparations of (S)-N-(9-PHENYLFLUOREN-9-YL)ALANINE AND (S)-DIMETHYL N-(9-PHENYLFLUOREN-9-YL)ASPARTATE. 

Apparently 9-phenylfluorenyl is not only a good anion but also a bad cation. The chloride probably shares in some of the resonance stabilization of the anion while the cation does not. Another example of a connection between the resonance of an anion and the properties of a related covalent compound is provided by the hydrocarbon triphenyl-methylcyclopentadiene, which has an unusually high dipole moment although it does not conduct in liquid sulfur dioxide.180... 

Protection of amines The 9-phenylfluorenyl group is introduced by treatment of an amine with 1 in CH3CN with K3P04 as base and Pb(N03)2 as a bromide scavenger. The 9-PhFl group is much more stable than the trityl group to protonolysis, but can be removed with TFA in aqueous CH3CN. 

Fernandez-Megia, E. Iglesias-Pintos, J. M. Sardina, F. J. Enantiomerically pure highly functionalized a-amino ketones from the reaction of chiral cyclic N-(9-phenylfluorenyl)... 

Excitation of the perchlorotriphenylmethyl radical leads to analogous product formation, although in this case the final perchloro-9-phenylfluorenyl radical is believed to form initially via a charge-separated intermediate and then a ring-closed species that subsequently loses two chlorine atoms [104]. 

The formation of the polymeric carbanions 81 of the fluorenyl-type is successful starting from the poly(para-phenylene) ladder polymer 71 with butyl-lithium as metallating agent. The degree of lithiation lies in the range of 90-95% (NMR). The UV/VIS absorption spectrum of these polymeric anions (81) is comparable with that of the 9-phenylfluorenyl anion and indicates the presence of mostly localized (anionic) sub-structures [101]. 

In the cationic polymerisation of a-methylstyrene by trityl salts the 9-phenylfluorenyl cation is the major product... 

W-4-Methoxybenzyl, 818 W-2,4-Dimethoxybenzyl, 819 W-2-Hydroxybenzyl, 820 W-9-Phenylfluorenyl, 822 W-Fluorenyl, 823 W-Ferrocenylmethyl, 823 W-2-Picolylamine W-Oxide, 823 W-7-Methoxycoumar-4-ylmethyl, 824 W-Diphenylmethyl, 824 W-Bis (4-methoxyphenyl) methyl, 825 W-5-Dibenzosuberyl, 825 W-Triphenylmethyl, 825... 

W-Bis (4-methoxyphenyl) methyl, 908 W-Bis (4-methoxyphenyl)phenylmethyl, 908 W-Diphenylmethyl, 909 W-Bis (4-methylphenyl)phenylmethyl, 909 W-Bis (4-methoxyphenyl)phenylmethyl, 909 W-Bis (4-methylsulhnylphenyl)methyl, 909 W-Triphenylmethyl, 909 W-9-Phenylfluorenyl, 910 W-Bis(trimethylsilyl)methyl, 910 W-f-Butoxycarbonyl, 910 W-Benzyloxycarbonyl, 911 W-Methoxycarbonyl, 912 W-Ethoxycarbonyl, 912 W-p-Toluenesulfonyl, 912 W-Trimethylsilylethylsulfonyl, 913 W,0-Isopropylidene Acetal, 914 iV,0-Benzylidene Acetal, 914 W,0-Methoxybenzylidene Acetal, 914 W.O-Formylidene Acetal, 915... 

Polyak, F., and Lubell, W.D. (1998)Rigid dipeptide mimics - Synthesis of enanti-opure 5- and 7-benzyl and 5,7-dibenzyl indolizidinone amino acids via enolization and alkylation of delta-oxo alpha,omega-di-[N-(9-(9-phenylfluorenyl))amino] azelate esters. J. Org. Chem. 63, 5937-5949. 

Houk control concerns electrophilic attack on alkenes, enolates and the like. The alkylation of enolate 56 would be an example if it were not held in a ring by chelation. It can in fact be difficult to tell whether chelation is involved or not with many enolates and the outcome of the reaction may tell which. Chamberlin s asymmetric preparation of both pyrrolidine 2,3-dicarboxylic acids 141 and 142 from natural aspartic acid illustrates this perfectly. The key to the stereochemical control is the very large protecting group 9-phenylfluorenyl-143 introduced by Rapoport.22... 

C-Methylation Procedure. The experimental details for the C-methylation of O-methyl coal have been published elsewhere (2) and are essentially those employed here with the following modifications. First, the O-methyl PSOC 1197 coal was obtained from unlabeled dimethyl sulfate using the conditions outlined earlier for the pH 12 O-methylation. Second, the O-methyl coal was not extracted with THF prior to C-methylation because only a small fraction (ca. 1%) of the sample is soluble in hot THF. Third, benzene, not diethyl ether, was used as the organic extraction solvent for all samples prepared with 9-phenylfluorenyl-lithium as base because 9-phenylfluorene and its byproducts have limited diethyl ether solubility. 

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