Tosylates, also

Tosylates also undergo elimination upon treatment with lithium salts in amide solvents. The a,/ -unsaturated ketone (106) is formed from the a-hy-droxy ketone tosylate in a fashion analogous to a-halo ketone eliminations. 

The charge transport and optical properties of the [Si(Pc)0]-(tos)y)n materials as y=0 -+ 0.67 are reminiscent of the [Si(Pc)0]-(BF4)y)n system, but with some noteworthy differences. Again there is an insulator-to-metal transition in the thermoelectric power near y 0.15-0.20. Beyond this doping stoichiometry, the tosylates also show a continuous evolution through a metallic phase with decreasing band-filling. However, the transition seems somewhat smoother than in the BF4 system for y)>0.40, possibly a consequence of a more disordered tosylate crystal structure. Both [Si(Pc)0]-(tos)y)n optical reflectance spectra and four-probe conductivities are also consistent with a transition to a metal at y 0.15-0.20. Repeated electrochemical cycling leads to considerably more decomposition than in the tetrafluoroborate system. 

The solvolysis reactions of cis and tram f-butylcyclohexyl tosylates also have been studied in NMA238. In both cases the primary product was 4-f-butylcyclohexene (no other cyclohexene products were detected) and much smaller quantities of cyclohexyl acetates and cyclohexanols were also recovered. The reaction rate was first order with respect to the tosylates. Similar to results of studies of the reaction in other solvents, the c/s-tosylate was solvolyzed more readily than was the tram compound. The stereochemical distribution of the minor products was significantly altered by small amounts of water (<1%) added to the NMA solvent. 

Pyiidinium)butanesulfonic acid tosylate, also is a good catalyst for these reactions [232], Ionic hquids have also been used in conjunction with solid silica supports. A combination of silica-bound sulfonic acid and the ionic liquid 1-butyl-3-decylimidazolium SbFs gave good yields with a variety of enones, including methyl vinyl ketone [233]. Another successful catalyst used a silica-bound imida-zolium-butanesulfonic acid [234]. Chiral D-camphorsulfonic acid used in conjunction with 1 -butyl-3-methylimidazolium bromide (bmim Br) gave excellent yields with 1,3-diarylpropen(Mies, but the ee was in the 20-30% range in most cases [235]. 

Benzyl ethers. A soln. of -octyl tetrahydropyran-2-yl ether in toluene treated with (methylthio)tributylstannane and BF3-etherate at 0°, stirred for 7 h, solvent replaced by DMF, benzyl iodide, CsF and 3A molecular sieves added, and the mixture stirred at room temp, for 20 h - benzyl octyl ether. Y 78%. F.e. ircl. 2-methoxyethoxymethyl ethers, acoxy compds., and tosylates, also oxo compds. with pyridinium chlorochro-mate, s. T. Sato et al.. Tetrahedron Letters 30, 1665-8 (1989) acoxy compds., direct method with MeCOCl (cf. 27,241), s. T. Bakos, I. Vincze, Synth. Commun. 19, 523-8 (1989). 

The hydrogenolyaia of cyclopropane rings (C—C bond cleavage) has been described on p, 105. In syntheses of complex molecules reductive cleavage of alcohols, epoxides, and enol ethers of 5-keto esters are the most important examples, and some selectivity rules will be given. Primary alcohols are converted into tosylates much faster than secondary alcohols. The tosylate group is substituted by hydrogen upon treatment with LiAlH (W. Zorbach, 1961). Epoxides are also easily opened by LiAlH. The hydride ion attacks the less hindered carbon atom of the epoxide (H.B. Henhest, 1956). The reduction of sterically hindered enol ethers of 9-keto esters with lithium in ammonia leads to the a,/S-unsaturated ester and subsequently to the saturated ester in reasonable yields (R.M. Coates, 1970). Tributyltin hydride reduces halides to hydrocarbons stereoselectively in a free-radical chain reaction (L.W. Menapace, 1964) and reacts only slowly with C 0 and C—C double bonds (W.T. Brady, 1970 H.G. Kuivila, 1968). 

Aminopalladation and subsequent carbonylation are also facile reactions. The carbonylation of substituted 3-hydroxy-4-pentenylamine as a carbamate (254) proceeds smoothly via the aminopalladation product 255 in AcOH to give 256[228). The protection of the amino group of the carbamate as tosyl amide is important in the carbonylation of 257 to give 258[229],... 

The most frequentiy used halo alkylating agents are aldehydes and hydrogen haUdes, haloalkyl ethers, haloalkyl sulfides, acetals and hydrogen haUdes, di- and polyhaloalkanes, haloalkenes, haloalcohols, haloalkyl sulfates, haloalkyl -tosylates, and miscellaneous further haloalkyl esters. Haloalkylations include halomethylation, haloethylation, and miscellaneous higher haloalkylations. Under specific conditions, bis- and polyhaloalkylation can also be achieved. 

N-Alkylations, especially of oxo-di- and tetra-hydro derivatives, e.g. (28)->(29), have been carried out readily using a variety of reagents such as (usual) alkyl halide/alkali, alkyl sulfate/alkali, alkyl halide, tosylate or sulfate/NaH, trialkyloxonium fluoroborate and other Meerwein-type reagents, alcohols/DCCI, diazoalkanes, alkyl carbonates, oxalates or malon-ates, oxosulfonium ylides, DMF dimethyl acetal, and triethyl orthoformate/AcjO. Also used have been alkyl halide/lithium diisopropylamide and in one case benzyl chloride on the thallium derivative. In neutral conditions 8-alkylation is observed and preparation of some 8-nucleosides has also been reported (78JOC828, 77JOC997, 72JOC3975, 72JOC3980). 

By similar procedures diazirines were prepared not only from simple aliphatic ketones but also from hydroxyketones and )3-aminoketones (B-67MI50800), and so were a large number of diazirines from steroidal ketones (65JA2665). Permanganate, bromine, chlorine and hypochlorite were used as oxidants. A one-step preparation of diazirines from ketones like 3-nonanone, ammonia and chlorine has been claimed in a patent (66USP3290289). 3,3-Diazirinedicarboxylic acid derivatives like (286) were obtained directly from oxime tosylates by the action of two moles of O-ethoxyamine (81AG(E)200). 

The THP ether can be converted directly to an acetate by refluxing in AcOH/AcCl (91 % yield). These conditions would probably convert other related acetals to acetates as well. The THP group can also be converted through the 0-SnBu3 to benzyl, MEM, benzoate, and tosylate groups. ... 

The tosyl group has also been removed by reductive cleavage with Na/NH3 (65-73% yield), Na/naphthalene (50-87% yield),and Na(Hg)/MeOH (96.7% yield)."... 

Ph2CHO)3PO, CF3COOH, CH2CI2, reflux, 1-5 h, 70-87% yield. Free alcohols are converted to the corresponding Dpm ethers. This reaction has also been used for the selective protection of amino acids as their tosylate salts (CCI4, 15 min-3 h, 63-91% yield). ... 

The ion-pair return phenomenon can also be demonstrated by comparing the rate of loss of enantiomeric purity of reactant with the rate of product formation. For a number of systems, including 1-aiylethyl tosylates, ftie rate of decrease of optical rotation is greater than the rate of product formation. This indicates the existence of an intermediate that can re-form racemic reactant. The solvent-separated ion pair is the most likely intermediate in the Winstein scheme to pl this role. 

Solvolysis rate studies also indicate that there is greater stabilization by a cyclopropyl group in a bisected geomeby. In tosylate 1, the cyclopropane ring is locked into an orientation which affords a perpendicular arrangement. It reacts 300 times more slowly than the model compound 2. Tosylate 3, which corresponds to the bisected geomeby, undergoes acetolysis at least 10 times faster than the model 2-adamantyl tosylate 4. ... 

The occurrence and extent of rearrangement of the 2-butyl cation have also been investigated by solvolysis studies using isotopic labeling. When 2-butyl tosylate is solvolyzed in acetic acid, C-2/C-3 rearrangement occurs only to the extent of 9% in the 2-butyl acetate which is isolated.Thus, under these conditions, most of the reaction proceeds by direct participation of the solvent. 

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