Reactions of Vinyl Type Carbocations Generated in Fluorosulfonic Acid with Benzene Derivatives. New Synthesis of Alkyl 3,3-Diarylpropenoates

Abstract

Vinyl type carbocations ArC + =CHX [X = CO 2 H, CO 2 Alk, C≡N, P(O)(OAlk) 2 ] generated from alkyl 3-arylpropynoates and related compounds in fluorosulfonic acid at -75 to -20°C react with various benzene derivatives, following the mechanism of electrophilic substitution of hydrogen. A new procedure for the synthesis of alkyl 3,3-diarylpropenoates having various substituents in the aryl fragments has been developed on the basis of protonation of the triple bond in alkyl 3-arylpropynoates.

Alkenylation of Arenes and Heteroarenes with Alkynes

“…A general approach to the alkenylation of arenes with aryl acetylenes conjugated with electron-withdrawing groups, under superacidic conditions, was presented in a series of reports. − Vinyl dications 530 , generated upon protonation of the electron-withdrawing substituent and the CC triple bond of compounds 529 , react with arenes, furnishing products of arene alkenylation 531 , as E- or Z- isomers (Scheme ).…”

Advances in Transition‐Metal‐Catalysed Alkyne Hydroarylations

“…The catalytic system generated with AgOTf/HOTf promoters was, however, more active but also less selective than the trifluoroacetic acid/silver trifluoroacetate one, because the increased strength of the acid promoter also favoured side reactions of the product. Moreover, it was recognized by us and other researchers that strong acids, such as HOTf, were able to promote the hydroarylation reaction of some alkyne substrates, most notably arylalkynes, even in the absence of a metal catalyst, which, of course, made it difficult to determine the intrinsic performance of the catalytic system with these substrates 27…”

One‐Step Addition of Sulfonic Acids to Acetylene Derivatives: An Alternative and Stereoselective Approach to Vinyl Triflates and Fluorosulfonates

“…Among them, dimers resulting from self-addition were mostly isolated (Table 1, Entry 12). [16] In triflic acid, the expected addition, however, did occur and afforded expected adducts 3f with very high E stereoselectivity and excellent isolated yield (Table 1, Entry 13). With a more electron-donating methoxy group, 1g in triflic acid gave expected adduct 3g, but surprisingly, an equivalent amount of the hydrolysis product, β-keto ester 4g, was also isolated ( Table 1, Entry 14).…”