Styrenes aryl triflates

RX also represents aryldiazonium salts [23 a, b], aryl triflates [25, 26], and hypervalent iodo compounds [71]. 1,3-Dienes and styrenes are the common constitutional types to result. In light of the enormous synthetic potential [9 a, 16], the Heck reaction is not treated properly in current textbooks and monographs [9 d, e], in which occasionally it is even ignored [9 g-i]. 

The total synthesis of the potent anticancer macrocyclic natural product lasiodiplodin was achieved in the laboratory of A. Furstner. The key macrocyclization step was carried out by the alkene metathesis of a styrene derivative, which was prepared in excellent yield via an intermolecular Heck reaction between an aryl triflate and high-pressure ethylene gas. 

The cross-coupling of aryl triflates with vinylstannanes gave a good yield of styrene derivatives with retention of the double-bond geometry in most cases. The reaction was applied to a synthesis of the quinoline alkaloid dubamine125 (equation 106). Other... 

Stilbenes synthesis by Heck coupling, 43 Stille coupling aryl triflate + organylstannane, 42 Stobbe condensation, 58-59 Stork reagent, 328-329 Strain, steric. See Steric strain Strecker s synthesis of a-amino acids, 50, 301 L-Streptose synthesis, 267 Styrene. See Benzene, ethenyl-Succinic acid. See Butanedioic acid Succinimide. See 2,5-Pyrrolidinedione Sugars. See Monosaccharides Oligosaccharides inexpensive derivs. pr. (table), 263-264 Sulfafurazole, 307 Sulfamethoxazole, 308 Sulfenic acids, esters ... 

Willis has similarly noted that indoles can be prepared via the cascade coupling of the aryl-halide and vinyl-triflate bonds in styrene 21 with primary amines (Scheme 6.41). Despite the fact that two different types of C—X bonds must be activated, this process proceeds with a single palladium catalyst (Pd2dba3/Xantphos), and a range of primary amines, carbamates and amides. More recently, even vinyl chlorides were found to participate in this coupling reaction [53]. 

Similar cross-coupling procedures have been used to prepare styrenes by the reaction of metalated aromatics with vinyl halides/triflates or, conversely, metalated alkenes with aromatic halides/triflates in the presence ofPd(Ph3P)4 (eq 6). Typically, ArCl are poor substrates in Pd(PPh3)4-catalyzed coupling reactions. However, by forming the chromium tricarbonyl complex of the aryl chloride, a facile coupling reaction with vinyl-stannanes can be achieved (eq 7). ... 

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