A general method was devised for the LiN(TMS)(2)/AgOTf (=2:1)-catalyzed intramolecular (5-exo-dig) cyclization of beta -alkynylamides 1 possessing alkyl, aryl or no functional groups at the terminal alkynes, to 5-alkylidene-2-pyrrolidinones 2. These 5-alkylidene-2-pyrrolidinones were oxidized to the diol-type alkoxylactams 3 by dimethyldioxirane (DMD) or mCPBA in MeOH. These alkoxylactams are useful as tertiary N-acyliminium ion precursors for the synthesis of threo-5-(1-hydroxyalkyl)-2-pyrrolidinone derivatives 5. (C) 2000 Elsevier Science Ltd. All rights reserved.
Silver salt-promoted direct cross-coupling reactions of alkynylsilanes with aryl iodides: synthesis of aryl-substituted alkynylamides
A direct cross-couplingreaction of 5-trimethylsilyl-4-pentynamides (alkynylsilanes) 1 with aryl iodides, promoted by silver carbonate in the presence of palladium catalyst, afforded aryl-substituted alkynylamides 2, which readily underwent cyclization to form benzylidenelactams 3. This coupling reaction proved to be a useful for synthesis of aryl-substituted alkynes.