Triflates alkylation

Cp has been discussed [170b]. Alkylation with haloalkanes (often iodoalkanes), triflates (alkyl, benzyl, cyclopropyl), or [RsO] (R = Me, Et) is often the best entry to vinylidenes of any particular system. Other common electrophiles, such as halogens (Cl, Br, I), acylium ([RCO] ), azoarenes ([ArN2] ), tropylium ([C7H7] ), triphenylcarbenium (trityl, [CPhs] ), arylthio (ArS) and arylseleno (ArSe) have also been used. 

HSAB is particularly useful for assessing the reactivity of ambident nucleophiles or electrophiles, and numerous examples of chemoselective reactions given throughout this book can be explained with the HSAB principle. Hard electrophiles, for example alkyl triflates, alkyl sulfates, trialkyloxonium salts, electron-poor car-benes, or the intermediate alkoxyphosphonium salts formed from alcohols during the Mitsunobu reaction, tend to alkylate ambident nucleophiles at the hardest atom. Amides, enolates, or phenolates, for example, will often be alkylated at oxygen by hard electrophiles whereas softer electrophiles, such as alkyl iodides or electron-poor alkenes, will preferentially attack amides at nitrogen and enolates at carbon. 

Vinyl triflate Alkyl, aryl, alkynyl Pd(AsPh3)2/CuI [172]... 

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