Zinc(II) Catalyzed Conversion of Alkynes to Vinyl Triflates in the Presence of Silyl Triflates

Abstract

The conversion of alkynes to their corresponding vinyl triflates in the presence of stoichiometric TMS-triflate was greatly facilitated by the triflate salt of several transition metal catalysts most especially Zn(OTf)2. Products are formed in high regioselectivity under mild conditions. Internal alkynes bearing an aryl substituent afford vinyl triflates with a modest preference for the Z-isomer especially with larger substituents. A mechanism is put forward to explain the unique role of silicon in this system.

Synthesis of 1,3-Substituted Cyclobutanes by Allenoate-Alkene [2 + 2] Cycloaddition

“…Spectral data were consistent with literature-reported values. 37 1 H NMR (400 MHz, CDCl 3 ) δ 7.35–7.27 (m, 5H), 7.27–7.21 (m, 2H), 6.87–6.79 (m, 2H), 5.35 (dd, J = 17.2, 1.3 Hz, 2H), 3.80 (s, 3H). 13 C NMR (100 MHz, CDCl 3 ) δ 159.4, 149.6, 141.9, 134.0, 129.5, 128.4, 128.2, 127.8, 113.6, 113.0, 55.4.…”

Stereoselective Synthesis of (Z)‐β‐Enamido Triflates and Fluorosulfonates from N‐Fluoroalkylated Triazoles

“…Vinyl triflates are usually prepared from carbonyl compounds either by trapping the respective enolate with a triflating agent or by treating the carbonyl compound with triflic anhydride in the presence of a bulky base . Other synthetic approaches are based on the introduction of triflate moiety into alkynes . Recently, Gaunt and Studer described regio‐ and stereoselective electrophile‐induced triflation of alkynes by hypervalent iodine reagents.…”

“…[11,[17][18][19][20] Other synthetic approaches are based on the introduction of triflate moiety into alkynes. [21][22][23] Recently,G aunt and Studer described regio-and stereoselective electrophile-induced triflation of alkynes by hypervalent iodine reagents. This methodol-ogy enabled the introduction of highly functionalized alkenes, [24] acrylonitriles, [25] andv inyl perfluoroalkanes [26] into organic molecules ( Figure 1A).…”

Selenide‐Catalyzed Stereoselective Construction of Tetrasubstituted Trifluoromethylthiolated Alkenes with Alkynes

“…To elucidate the reaction mechanism of difunctionalization, we did mechanistic studies to see whether the reaction went through a stepwise triflation–trifluoromethylthiolation process. Triflic acid could add to triple bond . When 1 a was treated with stoichiometric TfOH in deuterated chloroform for 4 h, triflated alkene 7 was generated in 62 % NMR yield with a poor stereoisomer ratio.…”

“…Triflic acid could add to triple bond. [18] When 1a was treated with stoichiometric TfOH in deuterated chloroform for 4h,t riflated alkene 7 was generated in 62 %N MR yield with ap oor stereoisomer ratio. Longer reactiont imes did not improvet he yield.…”