Organotriflates in the Stille Coupling

Organotriflates are important electrophiles in ShUe reachons owing to (i) their simple preparahon from readily available phenols and ketones and (ii) remarkable 

It has been claimed that for efficient triflate coupling, the use of LiCl as an additive is absolutely required, and this premise has been attributed to the 

Many other additives have been used in the Stille reaction and have shown modest improvements in cross-couphng rates and yields. These additives include stoichiometric CuO as well as Ag20 [234], and Et NCl [235]. Transmetallation of the metal ions with the Sn species or hgation of the halides to the Pd catalyst is assumed to be responsible for the observed rate improvements. 

AUcynylstannanes can cross-couple with a variety of other functional groups employing the Stille protocol. Couphng to acyl chlorides is a well-known procedure that affords aUcynylketones in respectable yields. Other reports include alkynyltin cross-couplings with a-haloethers and a-halocarbonyls, enol phosphinates and phosphonates, alkenyl(phenyl)iodonium salts, alkynyl halides, and allyl hahdes (Table 9.18). Alkynylstannanes have also been shown to cross-couple with iron halides under the Stille conditions to effectively form iron-carbon bonds. 

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