Tosylates alkynyl

Silver(I) Inflate and copper(I) triflate can be applied as catalysts A representative example is the preparation of alkynyl tosylates by the catalytic decomposition of alkynyl lodonium salts in the presence of these salts [727] (equation 67)... 

An alternative approach for alkynyl carboxylates involved reaction between [bis(acyloxy)iodo]benzenes and lithium acetylides [59]. Alkynyl iodonium salts afforded with sodium carboxylates in the presence of water 1-acyloxyketones heating in an excess of acetic acid gave similarly a-acetoxy ketones [60], Alkynyl tosylates and mesylates were obtained from the thermal decomposition of isolable alkynyl iodonium sulphonates. 

The presence of catalytic amounts of cuprous triflate or silver(I) sulfonates exerts a remarkable influence on the activation energy and regiochemistry of alkynyl(phenyl)-iodonium tosylate and mesylate decompositions5,6. Such reactions proceed in acetonitrile at room temperature and afford moderate yields of alkynyl tosylates and mesylates (equations 82 and 83)5,6. It is noteworthy, however, that the treatment of alkynyliodonium triflates (R = n-Bu, r-Bu) with cuprous triflate in acetonitrile does not afford alkynyl triflates6. Silver(I) catalysis has similarly been applied to the conversion of bis(alkynyliodo-nium) tosylates to bisalkynyl tosylates (equation 84)43. As might be expected, mono-tosylate esters are also produced in these reactions. 

Cleavage of N, N -duUkylk. leavage method. The furan ring to Alkynyl tosylates Tosyloxy und-assisted, AgOTf-catalyzed n... 

Stang has exploited the reaction of alkynyl tosylates with methyl... 

Acetylenic ethers and esters represent an important class of functionalized acetylene derivatives of the hypothetical alkynols, RC=COH. The chemistry of acetylenic ethers has been well developed since their first preparation about 100 years ago Several exhaustive reviews covering the literature on acetylenic ethers and their analogs up to 1985 have been published in the last 30 years. In contrast to acetylenic ethers, esters of alkynols were unknown until the mid-1980s when the first preparation of alkynyl tosylates was reported. In the following years a wide variety of alkynyl carboxylate, phosphate and sulfonate esters has been prepared from alkynyl iodonium salts. The chemistry of these novel derivatives of alkynols has been summarized in a recent review. In the last 10 years considerable interest and research activity has arisen toward alkynols themselves and such derivatives as alkynolate salts and silyl ynol ethers. The present chapter will cover the chemistry of acetylenic ethers and esters as well as related derivatives of ynols with emphasis on new developments in this subject during the last 5-10 years. 

A recent approach to lithium alkynolates involves cleavage of some ynol ethers and esters with methyllithium Desilylation of silyl ynol ethers with methyllithium at room temperature in THF solution leads to the selective formation of the corresponding alkynolates (equation 9) k Similarly, alkynyl tosylates can be selectively cleaved with methyllithium at low temperatures (equation 10). ... 

When reactions of alkynyl tosylates with acids are carried out under arfhydrous conditions, 1,1-vinylic diesters 122 can be isolated (equation 15f. The regio- and stereoselectivity of this reaction (equation 75) is consistent with an Ad mechanism, which was proposed for the first step of the acidic hydrolysis of alkynyl esters (equation 74). Moreover, the consequent hydrolysis of 122 yields the same products as the hydrolysis of alkynyl tosylates. ... 

Neutral hydrolysis of alkynyl tosylates and phosphates proceeds similarly to carboxy-lates to give the corresponding products, i.e. RC(0)CH20P(0)(0Et)2 and RC(0)CH20Ts, analogously to equation 76. 

Reactions of alkynyl esters with nucleophilic reagents usually involve the attack of the nucleophile on the electrophilic acyl moiety (i.e. C==0, P=0, SO2) but not the triple bond. A typical example of such a process is the formation of lithium ynolates in the reaction of alkynyl tosylates with methyl lithium (see equation 10 in Section II.B.l). Similarly, the base-catalyzed hydrolysis of alkynyl esters most likely proceeds via OH attack on the acyl moiety and the subsequent standard mechanistic steps. 

Chlorenol tosylates. HCl bubbled through a soln. of startg. alkynyl tosylate in methylene chloride at —20° under argon for ca. 5 min 3,3-dimethyl-1-chloro-l-(tosyloxy)-l-butene. Y > 99%. F.e. inch ene-l,l-diol sulfonates (from sulfonic acids) and 1-acoxyenol tosylates (from carboxylic acids) s. P.J. Stang, K.A. Roberts, J. Org. Chem. 52. 5213-7 (1987). 

The (alkynyl)aryl-A -bromanes mentioned above are stable enough to be isolated and may be employed in a variety of other coupling reactions. Alkynyl tosylates and tri-flates are interesting and useful products that can be obtained in this manner ... 

Dipolar cycloaddition of 5-aminofuro[3,2-f]pyridinium tosylate 140 and the alkynyl ester 141 yields furo[3,2-f]pyrazolo[l,5- ]pyridine 142 in moderate yield (Equation 33) <1999CCC539>. 

The reaction of lithium or sodium arylteUurolate with alkynyl phenyl iodonium triflates or tosylates. ... 

Alkynyl(phenyl)iodonium Tosylates Preparation and Stereospecific Coupling with Vinylcopper Reagents. Formation of Conjugated Enynes P. J. Stang and T. Kitamura, Department of Chemistry University of Utah, Salt Lake City, UT 84112... 

Alkynyl zincates (59), derived from 5-hexynyl tosylates, undergo a re-type endo cyclization to fonn cyclohexynes (60).58 This reaction takes place in competition with exo cyclization, leading to the formation of l-(cyclopentyhdene)alkylzincs (61). 

Alkynyl(phenyl)iodonium salts can be efficiently coupled with various organo-copper reagents. Direct coupling of alkynyliodonium tosylates 132 with vinyl-... 

Recent examples of the rearrangement or alkynylation pathway include conversions of arylethynyl- and er -butylethynyl(phenyl)iodonium tosylates 24 and 25 to alkynylphosphonates, -selenides, and -tellurides with the appropriate anion salts in DMF (Scheme 50) [145-147], and a similar synthesis of push-pull selenides and tellurides from alkynyliodonium triflates containing electron-withdrawing groups in the alkynyl moiety [148]. 

To a suspension of iodosylbenzene (1.1 g, 5 mmol) and the appropriate 1-trimethylsilyl-l-alkyne (5 mmol, prepared from 1-alkyne and trimethylchlorosilane in nearly quantitative yield, or obtained commercially) in chloroform (10 ml) was slowly added boron trifluoride etherate (710 mg, 5 mmol) at 0°C. The mixture was stirred at room temperature for 3-4 h, then recooled at 0°C and a solution of p-toluenesulphonic acid hydrate (3.8 g, 20 mmol) in water (20 ml) was added the resulting mixture was stirred vigorously for a few minutes. The organic phase was separated and the aqueous phase was washed with additional chloroform. The combined organic phase was washed with water, dried and concentrated. The residual oil solidified upon addition of ether. The solid was filtered, washed with ether and air-dried to give alkynyl phenyliodonium tosylates (62-89%). 

An interesting reaction between the bis phenyl iodonium triflate of acetylene and the silyl enol ether of acetophenone afforded an allene (PhCOCH=C=C=CHCOPh, 84%) [6], Also, alkynyl iodonium tosylates and carbon monoxide in methanol or ethanol, with palladium catalysis, furnished alkyne carboxylates [53]. 

The iodonium triflate (460 mg, 1 mmol) was added to a stirred slurry of anhydrous sodium p-toluene sulphinate (180 mg, 1.01 mmol) in dichloromethane (15 ml) at 20°C under nitrogen. After 15 min water (10 ml) was added and the phases were separated the aqueous layer was extracted with additional dichloromethane (2 x 5 ml), and the combined organic extracts were dried. The filtered solution was treated with hexanes (30 ml) and concentrated. The solid residue was purified by radial chromatography (silica gel, 200-400 mesh, dichloromethane-hexanes) to afford 3-tosyl-bicyclo[3.2.0]-3-heptene-2-one (197 mg, 75%), m.p. 164-165°C. The method is general for the preparation of sulphones with a cyclopentenone moiety other alkenyl iodonium salts gave alkynyl sulphones with sulphinates (Section 9.4.4). 

Stable esters coming formally from alkynols and carboxylic, sulphonic or dialkyl phosphoric acids were prepared for the first time via alkynyliodonium salts with the corresponding anion. Several alkynyl carboxylates were obtained by anion exchange of alkynyl iodonium tosylates the initially formed salts, PhI+C=CR RCO2, were converted spontaneously into the esters on elution through a chromatographic column packed with an anion-exchange resin (Pol+ArCOj) ... 

Sodium azide with alkynyl iodonium tosylates at — 70°C afforded an unstable ylide which in the presence of triethylsilane was transformed to different products, depending on the solvent [58] ... 

The conversion of terminal alkynes to alkynyl (phenyl) iodonium tosylates with HTIB, considered here as an instructive example, is best understood as a polar process initiated by electrophilic attack of HTIB on the triple bond of the alkyne (equation 5)46. Loss of H2Q... 

The synthesis of the first alkynyliodonium tosylates was achieved by the treatment of terminal alkynes with [hydroxy(tosyloxy)iodo]benzene (HTIB) (equation 8)8,10,11. Such reactions are generally conducted with an excess of alkyne in chloroform at reflux, although they can be carried out at room temperature, and dichloromethane can be employed as solvent. This procedure is, however, restricted to terminal alkynes in which R is either an aryl group or a bulky alkyl group. With linear alkyl groups (i.e. R = n-Pr, n-Bu, fl-C5Hn), phenyl(/ -tosyloxyvinyl)iodonium tosylates are obtained instead (equation 9)8. In some cases (R = /-Pr, /-Bu), mixtures of alkynyl- and (/ -tosyloxyvinyl)iodonium tosylates are produced8. ter -Butylacetylene appears to be the optimum substrate for this approach and has been employed with a series of [hydroxy(tosyloxy)iodo]arenes for the synthesis of various aryl(ter/-butylethynyl)iodonium tosylates (equation 10)9. 

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