ChemInform Abstract: Diastereoselective, Zinc‐Catalyzed Alkynylation of α‐Bromo Oxocarbenium Ions.

Abstract

Diastereoselective, Zinc-Catalyzed Alkynylation of -Bromo Oxocarbenium Ions. -The bromination of dihydropyran (I) in AcOH followed by a Zn-catalyzed alkynylation of resulting acetal (III) leads to trans--alkynyl--bromo tetrahydropyrans (V), which can be converted into derivatives (VI), (VII), and (IX). The alkynylation of substrates (XI) and (XIV) proceeds analogously. -(HAIDZINSKAYA, T.; KERCHNER, H. A.; LIU, J.; WATSON*, M. P.; Org. Lett. 17 (2015) 15, 3857-3859, http://dx.

New anionic cobalt(III) complexes enable enantioselective synthesis of spiro-fused oxazoline and iodoacetal derivatives

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Characterization and Utilization of the Elusive α,β-Unsaturated N-Tosyliminium: the Synthesis of Highly Functionalizable Skipped Halo Enynes

“…4h Careful screening for the creation of α,β-unsaturated N-tosyliminium ion reactive intermediates using various N,O-aminal adducts and Lewis acids reveals the first NMR and HRMS detection of A, which was generated from the reaction of 2a and BF 3 •OEt 2 , and followed by successful trapping with a catalytically generated alkynylzinc species (Scheme 1C). 14 The successful detection of A is attributed to the stable "ate" complex formation of nucleophilc benzoic acid with BF 3 (see Figure 2).…”