Pyridinium 1,1′-Binaphthyl-2,2′-disulfonates as Highly Effective Chiral Brønsted Acid−Base Combined Salt Catalysts for Enantioselective Mannich-Type Reaction
established, for the first time, a practical synthesis of chiral 1,1'-binaphthyl-2,2'-disulfonic acid (BINSA 1) from inexpensive BINOL. An efficient enantioselective catalysis in the Mannich-type reactions of diketones and ketoester equivalents with aldimines was developed using chiral 1-achiral 2,6-diarylpyridine (2) combined salts, which acted as convenient chiral tailor-made Brønsted acid-base organocatalysts
Highly Practical BINOL-Derived Acid-Base Combined Salt Catalysts for the Asymmetric Direct Mannich-Type Reaction
作者:Kazuaki Ishihara、Manabu Hatano
DOI:10.1055/s-0030-1258296
日期:2010.11
salt catalysts for asymmetricreactions, we developed a series of simple, practical, chiral BINOL-derived salt catalysts, such as chiral pyridinium 1,1′-binaphthyl-2,2′-disulfonates 1, chiral lithium(I) binaphtholate 2, chiral magnesium(II) binaphtholate (3), chiral calcium(II) phosphate 4, and chiral phosphoric acid 5, which were particularly effective for direct Mannich-type reactions. 1 Introduction
Tandem homologation-acylation chemistry: Single and double homologation
作者:Carley S. Henderson、Jennifer R. Mazzone、Amanda M. Moore、Charles K. Zercher
DOI:10.1016/j.tet.2021.132223
日期:2021.7
Furakawa-variant of the Simmons-Smith reagent results in homologation and production of an intermediate zinc enolate. Treatment of the enolate with various acylating agents generate products with both γ-dicarbonyl functionality and β−dicarbonyl functionality. In situ exposure of the acylated product to additional zinc carbenoid effects a second regiospecific homologation reaction.
Electrochemically-initiated Michael addition of chiral acetoacetic derivatives to methyl vinyl ketone: stereocontrolled construction of quaternary carbon centers
Stereoselective conjugate addition of chiral β-dicarbonyl derivatives to methylvinyl ketone was promoted by electrolysis, using a catalytic amount of electricity. With respect to the metal-catalyzed methods, the electrochemical, metal-free conditions resulted in enhanced reactivity of the electrogenerated enolates, so that the Michael addition was found to occur under mild conditions and short reaction
Tandem chain extension–iodomethylation reactions: formation of α-functionalized γ-keto carbonyls
作者:Qinglin Pu、Emerald Wilson、Charles K. Zercher
DOI:10.1016/j.tet.2008.06.063
日期:2008.8
Sequential exposure of a zinc-organometallic intermediate, generated through a zinc carbenoid-mediated chain extension reaction of a beta-keto carbonyl, to trimethylsilylchloride and iodine provided regioselective formation of an alpha-iodomethyl-gamma-keto carbonyl. The iodomethyl functionality can be further manipulated to provide side chains that are potential mimics of a-amino acid side chains. (C) 2008 Elsevier Ltd. All rights reserved.