Oxidation phase transfer-catalyze

Dehydrofluorination by primary and secondary aliphatic amines occurs at room temperature and is the basis of diamine cross linkmg, which occurs by dehydrofluonnation and subsequent nucleophihc substitution of the double bond The locus of dehydrofluonnation is a VDF unit flanked by two perfluoroolefin units This selectively base-sensitive methylene group also undergoes elimination as the first step in phase-transfer-catalyzed cross-hnking with quaternary ammo mum or phosphomum salts, bisphenols, and morganic oxides and hydroxides as HF acceptors [31, 32]... 

Poly(epichlorohydrin) (PECH) and poly(2,6 - dimethyl-1,4-phenylene oxide) (PPO) containing pendant mesogenic units separated form the main chain through spacers of zero to ten methylene units were synthesized and characterized in order to test the "spacer concept." Both polymers were modified by phase transfer catalyzed esterifications of the chloromethyl groups (PECH) or the bromobenzyl groups (brominated PPO) with potassium co -(4-oxybiphenyl) alkanoates and potassium u-(4-methoxy-4-oxybiphenyl)-alk.an oates. While PPO required ten methylene units as a spacer and 4,4 -methoxybiphenyl as mesogen to present thermotropic liquid crystalline mesomorphism,... 

The simplest model compound is cyclohexene oxide III. Monomers IV, V and VII represent different aspects of the ester portion of I, while monomers VII and VIII reflect aspects of both the monomer I and the polymer which is formed by cationic ring-opening polymerization. Monomers IV-VII were prepared using a phase transfer catalyzed epoxidation based on the method of Venturello and D Aloisio (6) and employed previously in this laboratory (7). This method was not effective for the preparation of monomer VIII. In this specific case (equation 4), epoxidation using Oxone (potassium monoperoxysulfate) was employed. 

Further variations on the epoxyketone intermediate theme have been reported. In the first (Scheme 9A) [78], limonene oxide was prepared by Sharpless asymmetric epoxidation of commercial (S)-(-)- perillyl alcohol 65 followed by conversion of the alcohol 66 to the crystalline mesylate, recrystallization to remove stereoisomeric impurities, and reduction with LiAlH4 to give (-)-limonene oxide 59. This was converted to the key epoxyketone 60 by phase transfer catalyzed permanganate oxidation. Control of the trisubstituted alkene stereochemistry was achieved by reaction of the ketone with the anion from (4-methyl-3-pentenyl)diphenylphosphine oxide, yielding the isolable erythro adduct 67, and the trisubstituted E-alkene 52a from spontaneous elimination by the threo adduct. Treatment of the erythro adduct with NaH in DMF resulted... 

One of the most useful classes of metal and phase transfer catalyzed reactions are carbonylation reactions. Cobalt carbonyl is a valuable catalyst for such processes(1 ). When used in conjunction with methyl iodide, acetylcobalt carbonyl [CH3C0Co(C0) ] is generated and can undergo addition to various unsaturated substrates including alkynes and Schiff bases. In addition, one can add this species to styrene oxides to give the enol... 

Ye, J., Wang, Y, Liu, R., Zhang, G., Zhang, Q., Chen, J. and Liang, X. A Highly Enantioselective Phase-transfer Catalyzed Epoxidation of Enones with a mild Oxidant, Trichloroisocyanuric acid. Chem. Commun. 2003, 2714-2715. 

Asymmetric phase-transfer catalyzed oxidation of olefin using sodium hypochlorite or potassium permanganate as metal anion sources is the typical example of this category. 

The telechelica,(i -bis(2,6-dimethylphenol)-poly(2,6-dimethylphenyl-ene oxide) (PP0-20H) [174-182] is of interest as a precursor in the synthesis of block copolymers [175] and thermally reactive oligomers [179]. The synthesis has been accomplished by five methods. The first synthetic method was the reaction of a low molecular weight PPO with one phenol chain end with 3,3, 5,5 -tetramethyl-l,4-diphenoquinone. This reaction occurred by a radical mechanism [174]. The second method was the electrophilic condensation of the phenyl chain ends of two PPO-OH molecules with formaldehyde [177,178], The third method consists of the oxidative copolymerization of 2,6-dimethylphenol with 2,2 -di(4-hydroxy-3,5-di-methylphenyl)propane [176-178]. This reaction proceeds by a radical mechanism. A fourth method was the phase transfer-catalyzed polymerization of 4-bromo-2,6-dimethylphenol in the presence of 2,2-di(4-hy-droxy-3,5-dimethylphenyl)propane [181]. This reaction proceeded by a radical-anion mechanism. The fifth method developed was the oxidative coupling polymerization of 2,6-dimethylphenol (DMP) in the presence of tetramethyl bisphenol-A (TMBPA) [Eq. (57)] [182],... 

With careful choice of reagent and reaction conditions, alkenes containing other functionalities can be selectively hydroxylated without complicating side reactions. For example, the oxidation may be carried out in the presence of ester, ether, sulfide, carboxylic acid, acetal, carbonyl, halo, alcohol and aryl groups. Regioselective hydroxylation is also possible in dienes in which one center is electron poor, and some selectivity is also found between isolated double bonds. For example, syn hydroxylation of diene (5) with a catalytic amount of osmium tetroxide and N-methylmorpholine N-oxide as the secondary oxidant gives diol (6) in 46% yield, and phase transfer catalyzed permanganate oxidation of diene (7) affords diol (8) in 83% yield. 

Since, for secrecy reasons, information on new processes and the state of their development is not always published, or only after long delays, the classification applied or recent developments may be misleading. For example, the potential of phase-transfer catalyzed processes may already be more important than the present literature indicates. The same statement could apply for areas such as amidocarbonylation, the synthesis of fine chemicals by means of metallocenes, the reductive/oxidative carbonylation of aromatic amines or nitro derivatives, Heck coupling using palladacycles and heterocyclic carbene complexes, catalytic McMurry coupling, or other proposed methods. Recent developments must therefore leave open the stage of development reached, perhaps signaling that at the time of publication no commercialized, licensable process is yet known to the scientific community. 

A side reaction has been identified in the phase transfer catalyzed Wittig reactions. Hydroxide ion attacks positively charged phosphorus to give a phosphine oxide and the methylaromatic hydrocarbon from cleavage of the benzylic carbon-phosphorus bond (Equation 1). The phosphonium ion derived from 9-chloromethy anthracene... 

Carbonylation, oxidative -, P-acoxycarboxylic acid anhydrides from ethylene derivs. 44, 640 Carbonylation, phase transfer catalyzed 44, 807... 

Oxidation, benzylic, phase transfer-catalyzed 43, 139 Oxidations... 

Olefin oxidation, for example, of trons-stilbene, was conducted using PEG 600 to yield benzoic acid [165]. In addition to the more conventional oxidations we have described, PEGs have been used for phase transfer catalyzed autooxidation of weak carbon acids [ 166]. 

Carbanions have been oxidized under phase transfer conditions in the presence of both crown ethers and cryptates. The substrate which has been most studied is fluorene which undergoes phase transfer catalyzed air oxidation to yield fluorenone in high yield according to equation 11.11 [10, 18]. Crown complexed f-butoxide in... 

Sodium hypochlorite tetrabutylammonium hydrogen sulfate NaOCUBu N HSOf Phase transfer catalyzed oxidations with hypochlorite... 

Percec also synthesized poly(2,6-dimethyl-l,4-phenylene oxide) by phase-transfer catalyzed pol5mierizati(Mi of 4 in the presence of 2,4,6-trimethylphenol 6 as a chain initiator (Scheme 7a) [11]. 

Nucleophilic Reactions. Useful nucleophilic substitutions of halothiophenes are readily achieved in copper-mediated reactions. Of particular note is the ready conversion of 3-bromoderivatives to the corresponding 3-chloroderivatives with copper(I)chloride in hot /V, /V- dim ethyl form am i de (26). High yields of alkoxythiophenes are obtained from bromo- and iodothiophenes on reaction with sodium alkoxide in the appropriate alcohol, and catalyzed by copper(II) oxide, a trace of potassium iodide, and in more recent years a phase-transfer catalyst (27). 

The reaction with ammonia or amines, which undoubtedly proceeds by the SnAt mechanism, is catalyzed by copper and nickel salts, though these are normally used only with rather unreactive halides. This reaction, with phase-transfer catalysis, has been used to synthesize triarylamines. Copper ion catalysts (especially cuprous oxide or iodide) also permit the Gabriel synthesis (10-61) to be... 

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