Cycloalkenyl triflates

Kuhn and Neumann reported examples of Stille coupling in which the tin moiety was chemically fixed on a polymer support [181] vinyl, allyl, and alkynyl groups were transferred in reactions with acid chlorides, a cycloalkenyl iodide, and a cycloalkenyl triflate. 

Ready availability of cycloalkenyl triflates from ketone precursors often renders them superior to the corresponding halides in synthesis. The syntheses of arylated cycloalkenes [164] and 2-substituted carbapenems (Scheme 2-59) [165] have been achieved in excellent yields by the reaction with triflates. 

Carbonylation. The conversion of ArOTf to ArCHO with S3mgas (reductive carbonylation) simply uses the Pd(OAc)2 - DPPP system as catalyst. Homologation of cycloalkenyl triflates to the corresponding enals is perhaps favored by the hindered bis-phosphine 1. ... 

Tandem cyclization/3-substitution can be achieved starting with o-(trifluoro-acetamido)phenylacetylenes. Cyclization and coupling with cycloalkenyl trif-lates can be done with Pd(PPh3)4 as the catalyst[9]. The Pd presumably cycles between the (0) and (II) oxidation levels by oxidative addition with the triflate and the reductive elimination which completes the 3-alkenylation. The N-protecting group is removed by solvolysis under the reaction conditions, 3-Aryl groups can also be introduced using aryl iodides[9]. 

Phosphoniosilylation. Cyclic enones treated with TBDMS triflate and triphenylphosphine in THF at it provide the corresponding l-(3-f-butyldimethylsilyloxy-2-cycloalkenyl)triphenyl-phosphonium triflates (eq 8) which, upon lithiation with n-butyllithium followed by Wittig reaction with aldehydes, afford various conjuated dienes. ... 

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