Enantioselective Allylation of Oxocarbenium Ions Catalyzed by Bi(OAc)₃/Chiral Phosphoric Acid

Abstract

Phthalides as the crucial core skeletons are found extensively in natural products and biological active molecules. Herein we disclose an asymmetric allylation of 3-hydroxyisobenzofuran-1­(3H)-ones with boron allylation reagents to construct chiral phthalide derivatives. The simple Bi­(OAc)3/chiral phosphoric acid catalytic system proves to be efficient in this method, delivering the desired chiral 3-allylisobenzofuran-1­(3H)-ones in good yields (up to 99%) and high enantioselectivities (up to 99.5:0.5 e.r.) under mild conditions. The large-scale reaction and diverse transformations of products to various scaffolds with potential biological activities render it more attractive. Moreover, the mechanism was preliminarily explored by control reactions, mass spectrometry, deuterium experiment, and DFT calculations.

100th Anniversary of Macromolecular Science Viewpoint: The Past, Present, and Future of Stereocontrolled Vinyl Polymerization

“…While recent efforts have revealed catalyst design principles, in some cases, significant effort is needed to develop general methods that control the facial addition of prochiral nucleophiles to the sp 2 -hybridized cationic chain end. Recent advances in stereoselective glycosylation and small-molecule asymmetric catalysis − provide inspiration using similar reactive intermediates encountered during cationic polymerization. Ultimately, combining stereoselective cationic polymerization with methods to control the molecular weight and Đ of these materials promises the discovery of functional polymeric materials derived from simple and inexpensive building blocks.…”

Redox-Neutral Organometallic Elementary Steps at Bismuth: Catalytic Synthesis of Aryl Sulfonyl Fluorides

“…On one hand, the extensively studied and long-known Lewis acid catalysis, where the bismuth catalyst does not undergo redox processes or participate in catalytic organometallic elementary steps. 17 On the other hand, bismuth can undergo redox catalysis 18 through elementary organometallic steps, maneuvering between Bi(I)/(III), 19 Bi(II)/Bi(III), 20 or Bi(III)/(V) 21 ( Figure 1 B). Herein, we demonstrate that a third catalytic platform for bismuth can also be operative in the conversion of (hetero)aryl boronic acids to the corresponding sulfonyl fluorides.…”

“…At present, two main catalytic platforms dominate the field of bismuth catalysis in organic synthesis. On one hand, the extensively studied and long-known Lewis acid catalysis, where the bismuth catalyst does not undergo redox processes or participate in catalytic organometallic elementary steps . On the other hand, bismuth can undergo redox catalysis through elementary organometallic steps, maneuvering between Bi­(I)/(III), Bi­(II)/Bi­(III), or Bi­(III)/(V) (Figure B).…”

Chiral organophosphates as ligands in asymmetric metal catalysis

“…A bismuth-phosphate catalyst was used by Cheng and coworkers in the enantioselective allylation of oxocarbenium ions (see figure 14). 43 This was based on previous work by the same group on the asymmetric allylation of isatin 44 and cyclic imines. 45 Now the Cheng-group reports the reaction of 3-hydroxyisobenzofuran-1(3H)ones 53 and allylboranes 54 to give the corresponding 3-allylisobenzofuraone-1(3H)ones 55 in the presence of a bismuth-monophosphate-diacetate complex.…”

“…14 Enantioselective allylation of oxocarbenium ions catalyzed by a Bi-phosphate. 43 Fig. 15 Stereoselective polymerization of vinyl ethers catalyzed by a Ti-phosphate.…”