While iminium salts generated by the oxidation of amino ketene silyl acetals show intriguing reactivities to give useful γ-oxo-α-amino esters via reactions with silyl enol ethers in good yields, new iminium salts are also prepared by the oxidation of amino silyl enol ethers. They undergo facile addition reaction with various nucleophiles to give α-amino ketone derivatives in good yields.
Zinc catalysis: Zinc triflate in a nitrile solvent behaved as an effective catalyst for dehydrogenative N‐silylation with a variety of indoles and hydrosilanes (see scheme). The addition of pyridine greatly accelerated the N‐silylation reaction to produce N‐silylindoles exclusively in high to excellent yields.
Simple inexpensive boron electrophiles for direct arene borylation
作者:Alessandro Del Grosso、Matthew D. Helm、Sophia A. Solomon、Dolores Caras-Quintero、Michael J. Ingleson
DOI:10.1039/c1cc14226g
日期:——
Electrophilic direct borylation is facilitated, and arene substrate scope enhanced, by using electrophiles derived from inexpensive reagents; specifically an amine, BCl3 and AlCl3.
Pinacol Boronates by Direct Arene Borylation with Borenium Cations
作者:Alessandro Del Grosso、Paul J. Singleton、Christopher A. Muryn、Michael J. Ingleson
DOI:10.1002/anie.201006196
日期:2011.2.25
Borenium does it direct: A boron analogue of the Friedel–Crafts reaction uses inexpensive catecholatoborenium cations that are sufficiently electrophilic to borylate arenes by electrophilic aromatic substitution. The direct arene borylation proceeds with high regioselectivity for a range of anilines, N‐heterocycles, and thiophenes. Subsequent one‐pot transesterification provides the synthetically useful
Ruthenium-catalyzed enantioselective propargylation of l-(triisopropylsilyl)-1H-indoles with propargylicalcohols gives the corresponding β-propargylated indoles in good yields with high enantioselectivity. Reactions with l-(l-naphthyl)prop-2-yn-l-ol achieve the highest enantioselectivity (up to 95% ee).