KOSER Tosylation

KONIG Benzoxazin synthesis 214 KORNBLUM Aldehyde synthesis 215 KOSER Tosylation 216 Kostaneeki 321... 

Lodaya, J.S.. and Koser. G.E. Alkynyliodonium salts as alkynylating reagents. Direct conversion of alkynylphenyliodoniiun tosylates to dialkyl alkynylphosphonates with trialkyl phosphites, J. Org. Chem., 55. 1513. 1990. 

In contrast to carboxylic acids, p-toluenesulfonic acid and other organosulfonic acids do not form stable organoiodine(III) derivatives of the type ArI(0S02R)2. The existence of several such derivatives has been proposed in the literature however, none of them was isolated as an individual, stable compound. For example, Koser and Wettach reported in 1977 some evidence for the intermediate formation of the ditosylate PhI(OTs)2 in the reaction of PhICl2 with silver tosylate, but an attempt to isolate this compound failed and the final isolated product was [hydroxy(tosyloxy)iodo]benzene, PhI(OH)OTs [195]. 

Preparation A common synthetic approach to alkynyliodonium salts involves the reaction of an electrophilic X -iodane with a terminal alkyne or its silylated, stannylated, or lithiated derivative. In the early 1980s, Koser and coworkers found that [hydroxy(tosyloxy)iodo]benzene 75 reacts with terminal alkynes 344 upon gentle heating in chloroform or dichloromethane to form alkynyliodonium tosylates 345 in moderate to low yield (Scheme 2.98) [199,471,476]. 

Alternate Names HTIB Koser s reagent phenyllodine(III) (hydroxyl)tosylate. 

The alkynylation of phosphorus nucleophiles has been less investigated (Scheme 7). Ochiai and co-workers first demonstrated in 1987 that the alkynylation of triphenyl-phosphine was possible with alkynyliodonium tetrafluoroborate salts under light irradiation (Scheme 7, A) [69]. The reaction most probably involves radical intermediates. In 1992, Stang and Critell showed that light irradiation was not needed if alkynyliodonium triflates were used [70]. Later, this methodology could be extended to other triaryl- or alkyl phosphines [71, 72]. In 1990, Koser and Lodaya also reported the synthesis of alkynylphosphonates by the Arbusov reaction of alkynyliodonium tosylates with trialkyl phosphites (Scheme 7, B) [73]. Alternatively, the same compotmds can be obtained by the reaction of alkynyliodonium tosylates with sodium phosphonate salts [74]. 

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